Why I prefer Cinema 4D over Maya

April 3, 2010

If you plan to develop something in 3D, maybe you’ve wondered what software package would be the best for you, (unless you plan to develop your own and reinvent the wheel). Some of you may already know that I have a preference for Cinema 4D, but I would like to discuss why. That doesn’t mean I necessarily mandate Cinema 4D to be “better” than Maya, it really depends on your needs or preference.

Which is more efficient at rendering?

In the 2008 fall semester at Collin College, I decided to try an experiment. I rendered a turntable of my final character project and a flythrough of my environment project. (See the projects in my 3D Modeling and Rendering II gallery.)

I used both Maya 2008 (Mental Ray) and Cinema 4D 10 with a near identical scene setup for the turntable. I tried a few different settings for the turntable in each software package, but the results were virtually similar.

For the flythrough in Cinema 4D, I included my character lying on the bed since I hadn’t imported it into Maya. Notice that I also used a slower computer for the flythrough render in Cinema 4D. This wasn’t intentional, I simply didn’t have the opportunity to use the school’s faster computer.

Each computer had 3GB of memory. The render resolution was 720x486.

Animation	Animation Length	Computer Speed	Software	Render Time
Turntable	8 seconds	8 cores @ 2.0GHz	Maya	1 hour
Turntable	8 seconds	8 cores @ 2.0GHz	Cinema 4D	7 minutes
Flythrough	16 seconds	8 cores @ 2.0GHz	Maya	1.5 hours
Flythrough	16 seconds	2 cores @ 2.4GHz	Cinema 4D	20 minutes

Please note that I didn’t use anything special like global illumination in these renders. Also, Cinema 4D has actually doubled its own render time in version 11.5, whether using things like global illumination or not. Unfortunately I still only have version 10 as of this writing.

I was first introduced to Maya in spring 2006 at Collin College. Render time was one of the first things I wondered about. Why did it take so long to render something on a computer that’s faster than mine? I thought it may have been the network or background tasks, but running Cinema 4D from my USB drive still outperformed Maya. If you think something was completely amiss concerning this test, please tell me what was wrong and/or suggest some settings I should use.

What about workflow?

Workflow is really a matter of preference. I’ve heard people say Cinema 4D is good for learning, but I have to ask, why stop there? I think I can understand why it would be easier to lean Cinema 4D. It has an intuitive and well organized interface which is also highly customizable.

Maya’s interface seems slightly more cryptic but basic tasks are still easily understood. Unless you understand what the terms mean, you could get lost. If you’re used to it, there’s no problem.

In another note, I think Blender 3D would dominate if it had a customizable interface so people that like to be flexible with other software could actually use it along with the others. I know there’s a few people that tout Blender’s interface, but it’s worthy to note that not everyone works the same way. What’s efficient to one person may not be efficient to another who has equally tried several methods.

What about the bugs?

On a few occasions I have had Cinema 4D crash on me. It gives me a notification and usually saves a copy of my open file in an error report folder. As a result, I usually don’t loose any work. There are occasions where the saved error file is understandably corrupt, but I have never had any problems with other saved files being corrupt.

Unfortunately, I have heard much worse things about Maya from classmates and instructors at Collin College and in UTD’s ATEC department. Instructors always seem to warn about Maya crashing and corrupting files. I also hear of complaints about bugs with new releases of Maya and instructors suggest using a version below the latest.

The only other problem I’ve seen with Cinema 4D is crashing while using OpenGL on a computer it wasn’t installed on (i.e. running from my USB drive). Once I disable it however, there isn’t a problem.

What about scripting?

Scripting is probably what makes Maya attractive, especially because it uses Python. Scripting is essential when it comes to game development. Cinema 4D has scripting using COFFEE and Xpresso which aren’t really common at all. However, like Maya and many others, it also comes with an SDK that uses C/C++.

Is Autodesk the standard?

Metaphorically scratching my head, I couldn’t help but wonder why Maya is considered an industry standard. Asking a fellow student in my small business class, who does architectural work with AutoCAD, said because it’s Autodesk. He likewise voiced his grievances and frustration with buggy Autodesk software.

I suppose I could liken Autodesk to Microsoft, but I have to give Microsoft credit. Microsoft realizes it has real competition in the corporate world whereas Autodesk doesn’t truly seem to notice. People use their products because companies use their products. However, even Adobe keeps a pretty high standard for their software quality.

Anthropomorphic Character Modesty (1 of 2)

March 27, 2010

In our normal world, there is a general standard where humans wear clothing and animals don’t. In the world of art and animation however, we mix the two in the form of anthropomorphic characters, and this complicates things. When does it become necessary to draw the line with clothing and modesty? Let’s examine this prior to a survey I wish to conduct.

Does it matter?

It’s likely that most artists don’t closely consider or even care whether what they present is modest or immodest. But if you’re targeting a mass audience, it becomes necessary to address this issue. It’s also likely that most people don’t care, but you need to consider your specific audience. As a Christian according to the New Testament and as an artist, I must be particularly aware.

Whether you’re a Christian artist/viewer or not, you likely have standards. But those standards are for humans, so anthropomorphic characters can be ambiguously sticky.

What are modesty and immodesty?

Before we can assess what’s “modest” and what’s “immodest” we need to know what they mean. Here are some definitions for modest:

• the Free Online Dictionary, Thesaurus and Encyclopedia: Modest
• Dictionary.com: Modest
• An American Dictionary of the English Language (Volume 2; New York: S. Converse, 1828), by Noah Webster

Here are some definitions for immodest:

• the Free Online Dictionary, Thesaurus and Encyclopedia: Immodest
• Dictionary.com: Immodest
• An American Dictionary of the English Language (Volume 1; New York: S. Converse, 1828), by Noah Webster

Key characteristics of modesty:

• “disinclination to call attention to oneself”
• “conventional proprieties”
• “free from showiness or ostentation”
• “having or showing regard for the decencies of behavior, speech, dress, etc.”

Key characteristics of immodesty:

• “offending against sexual mores in conduct or appearance”
• “indecent”
• “shameless”
• “unchaste”
• “lewd”
• “obscene”
• “arrogant”

What makes an anthropomorphic character modest or immodest?

Animals don’t wear clothing and are generally modest. However, as an artist adds more human characteristics, we naturally perceive it more like a human. Therefore it becomes necessary to add clothing.

And vice versa, when the character is more animal like, clothing may be unnecessary if no “sexy bits” are present. Clothing may even distract the viewer from the main point of the subject matter. An unclothed character more animal-like than human-like isn’t generally lewd assuming the subject matter isn’t lewd.

Unfortunately, what makes a character modest or immodest is not only dependent on an artist’s presentation, but a viewer’s perception. Therefore, it becomes necessary to know the average viewer’s perception. The keyword is “average,” there are always exceptions. Some won’t find anything particularly immodest while some will find practically everything immodest.

There’s always some out there who will perverse

If you’re an artist that’s concerned about what you present, don’t beat yourself up when things seem to go awry. Even if you actually left nothing to misinterpretation, some people can still find a way to pervert it. Your work will sometimes be criticized and taken out of context.

Consider that even God’s work, the perfect Author and Artist, is sadly misrepresented all the time. Concerning modesty and clothing (for humans), these are Biblical standards I adhere to (see context for details):

• Exodus 20:26 - “Nor shall you go up by steps to My altar, that your nakedness may not be exposed on it.”
• Exodus 28:42 - “And you shall make for them linen trousers to cover their nakedness; they shall reach from the waist to the thighs.”
• Isaiah 47:1-3 - “Uncover the thigh, Pass through the rivers. Your nakedness shall be uncovered, Yes, your shame will be seen;”
• Nahum 3:5 - “I will lift your skirts over your face, I will show the nations your nakedness, And the kingdoms your shame.”
• Matthew 5:28 - “But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart.”
• 1 Corinthians 6:19 - “Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own?”
• 1 Timothy 2:9 - “In like manner also, that the women adorn themselves in modest apparel, with propriety and moderation, not with braided hair or gold or pearls or costly clothing,”

Hopefully I’ll have some statistics to present before the Summer of 2010.

Adding batteries to your devices

March 24, 2010

Whether you’re on vacation taking pictures and video or working on your laptop in the park, extended battery life can be a big help. Maybe you’ve lost or had a cell phone charger die and wondered if you could use an old one of the same voltage if it had the same connector. Adding more battery power or adapting connectors gives you a lot of flexibility. If you do it yourself, you may find it’s very inexpensive.

Develop a Common Connector System for Your Devices

Before you can add batteries to a device, you need to be able to connect them. I know “universal connectors” exist, but there are still plenty of devices that use special connectors. A simple solution is to splice into the cord and add RCA in-line connectors. I recommend using male plugs for the device connector and female jacks for the power source with a positive center and outer negative shield.

In-line RCA female jack connectors aren’t as common as male plugs, but they’re still inexpensive compared to other connectors. Here’s a few places to get them:

• Alltronics: Audio Connectors
• Minute Man Electronics: Female In-Line RCA Jacks
• HomeTech Solutions: RCA Female In-Line Jack

Here’s an example of my system:
 

Where can I get battery holders?

• BatterySpace.com: Battery Holders/ Racks
• Radio Shack (locally or online)
• Newark.com: Battery Holders
• Amazon.com: Battery Holders

How many batteries do I need?

If you match the capacity, Ah or mAh (milliamp hours), of the existing batteries with that of the added batteries, then you’ll nearly double its operating time. But, you can have as many milliamp hours as you want wiring batteries in parallel. The important thing to remember is to match the voltage of the device’s power supply.

If the device uses a transformer, use a multimeter to measure the actual device’s power supply output voltage when it’s connected to the device. A transformers’ output voltage is usually higher when disconnected while the specified output can be lower.

NiMH (and NiCd) battery cells (a single AAA, AA, C, D, etc.) are 1.2V per cell (nominal voltage). When charged, the cells are 1.4V. (Li-ion cells are 3.6V nominal and 4.2V charged.) If your device uses 5V, then you would need 4 NiMH batteries in series for 4.8V (5.6V charged). Most laptops use 19.2V from their power supply, so that would be 16 NiMH batteries in series.

What battery type should I use?

If you plan to extend the battery life of a device, a good choice is NiMH because of its availability and flexibility. Nearly every battery pack used in today’s devices use one of three types of chemistries:

• NiCd (Nickel Cadmium)
• NiMH (Nickel Metal Hydride)
• Li-ion/Li-polymer/LiFe (Lithium Ion/Polymer/Iron Phosphate)

NiMH in particular is a common rechargeable battery type used in many applications. NiCd batteries are often used in devices with frequent or regular usage (like power tools or electric toothbrushes) or standby usage (emergency lights). Li-ion batteries are used in devices made to be particularly lightweight and require protection circuitry. LiFe is much safer than Li-ion.

Make Your Own UPS

March 19, 2010

Before uninterruptible power supplies (UPS) were made as a single unit, people had to make one with batteries, an inverter, and a charger. There are still advantages to doing this, like expandability and knowing how it will react to a situation. If you consider yourself an electronic hobbyist, you may find this is a fairly simple project.

Choosing Your UPS Type

The table below shows the basic differences between two major types of UPSs. The parts listed would be used for a UPS lasting about 15 minutes putting out 400W. If you can find them less expensive or want a different brand, go for it! If you want more power or a longer time, use a bigger battery, inverter, or charger accordingly.

	Standby/Line interactive	Online
What it does	maintains battery charge; it switches to the inverter powered by the battery during an outage	a charger powers the battery and inverter; it stops charging during an outage while the battery continues to power the inverter
Cost	less	more (the charger)
Complexity	more (the relay switch)	less
Power usage	less (small float charger)	more (charger and inverter; heat loss due to conversion inefficiencies)
Noise	less (fan on inverter during outage)	more (fans on the charger and inverter)
Parts list	12V/12Ah SLA battery - High-Tech Battery Solutions - BatterySpace.com - Zbattery.com 400W AC inverter (with surge capability) A small float charger (~13.6V; not your average car battery charger!; you could build your own) Wires and terminals to connect the battery, inverter, and charger in parallel (local hardware store) 125VAC/10A double pole, double throw relay (125VAC coil) AC outlet and cover (local hardware store or the end of a grounded extension cord) Two grounded power cords (local hardware store or unused power cords) A small project box for the relay, socket, and cords	12V/12Ah SLA battery - High-Tech Battery Solutions - BatterySpace.com - Zbattery.com 400W AC inverter (with surge capability) A 45Amp float charger (~13.6V, not your average car battery charger!) Wires and terminals to connect the battery, inverter, and charger in parallel (local hardware store)

Putting it Together

Regardless of what UPS you’re building, you will inevitably wire the battery, the output of the charger, and the input of the inverter in parallel. That means all the black negative wires go together and all the red positive wires go together. You’ll need large wire to handle the current. Only the small float charger will use smaller wire.

Setting up the Online UPS

Once you’ve wired everything in parallel, you’re done! Just plug in the charger into an outlet and plug in your equipment into the inverter outlet. If the battery is charged, unplug the charger and make sure it works.

Building the Switch Box for the Standby UPS

The Schematic

 
If you’re not an electronic hobbyist, don’t let the diagram scare you too much, just follow it. The relay I suggested should have it’s own diagram on the top cover. The packaging of most relays indicate what pin number on the schematic corresponds to the pin number on the relay itself. Just match up their schematic with the schematic above. It should be very similar.

See “How it Works” below for an explanation of what “NC” and “NO” means.

For you electronic hobbyists, you know most relays use 12VDC. If you can’t find a relay that has a 125VAC coil like the one I listed, use a small 12V transformer and rectify the output to DC (or use an unused cell phone charger). Don’t use a capacitor! This would cause a delay in the relay switching time.

Putting it in the Box

Place everything in the box however you like, or at least in a way that isn’t obviously hazardous. If you have cords going out of drilled holes, make sure you smooth the edges of those holes. Tie knots into the cords inside the box so they can’t be pulled out. I used IEC connectors myself, check out my box (in the lower right hand corner).

Connections to the relay should be soldered. Also make sure those connections can’t sort against the box if it’s metal. If it is loose in the box, cover it with electrical tape.

If you’re real cheap, you could just run cords (plugs and an extension cord end) directly to and from the relay and tape it up. … Not that I would recommend that. I like things to look neat.

Setting up the Standby UPS

1. Make sure you’ve already wired the battery, charger, and inverter in parallel.
2. Plug in your switch box line input into a wall outlet or power strip. The relay should click.
3. Plug in your switch box inverter input into the inverter.
4. Plug in your equipment into the power output of your switch box.
5. Test it by unplugging your switch box from the wall, or switch off the power strip.

How it Works

The switch box works by using a relay to switch AC line power to inverter power when the line is off (outage). When line power is on, the relay is on. The relay closes it’s contacts that are normally open (NO), causing the line power to pass through to the socket and the equipment plugged into it.

When the relay is off (loses it’s power from the line), the normally closed (NC) contacts are closed, and now power from the inverter powers your equipment.

Since this isn’t a “real” UPS, it doesn’t synchronize it’s output frequency with that of the line. If you plan to use it with a computer and monitor, which usually rectify their input to DC anyway, it shouldn’t really matter too much. I’ve never had any problems.

Using a Store-bought UPS

You might be able to buy a good UPS, but my experience is limited in this area. I’ve only had a 400VA APC UPS. It worked great for a while and it always seemed to test the battery when you turned it on. But it would always switch to the battery and back to the line when I turned my printer on.

A year or so later, the APC UPS decided to just turn my computer off when I turned my printer on, failing to do its job. It wasn’t the battery because I continue to use the same battery for my own standby UPS. At some point, it just turned my computer off at random. The “cure” was now worse than the “disease” and intolerable. (UPDATE: It turned out to be the cheap relay. Read my article When electronics think they’re smarter than you for details.)

This doesn’t mean you can’t buy a good UPS, I just don’t know where. I didn’t get another one because I already had a good battery (which is a large part of the price). All in all, it seemed like the APC UPS was trying to protect itself more than the equipment that was plugged into it–too many stupid “smart” circuits.

Let’s go camping with solar

March 17, 2010

Let us consider a possible scenario. You want to go camping and want to use solar power to charge a 12V battery connected to a 120VAC inverter to power your stuff. Calculating battery size and solar panel power is important if you don’t want to be left without power. Amp hours (Ah) work much the same way as watt hours (Wh). Multiply battery voltage times the Ah rating and you get Wh (more or less), but there are also other things to consider.

Let’s setup a possible scenario

Let’s say you would like to take a primitive camping trip. You want to make sure you have enough power to occasionally run your laptop and charge batteries for your camera. You would like to run your laptop for 4 hours a day and charge 4 AA NiMH batteries a day. Let’s also assume you’ll be gone for 5 days.

As we go through this scenario, keep in mind that this same deductive reasoning can be applied to many different scenarios. Maybe you want to power:

• something during an outage
• your RV’s appliances
• your laptop through a 14 hour flight using a few parallel sets of 16 NiMH batteries in series
• a remote pond water pump

Also keep in mind that this is only a general guide. It does not consider discharge rate, temperature, or various other factors. For details, check out the following:

• Battery-Web.com - Frequently Asked Questions (FAQ) (see last question)
• Effects of Discharge Rate and Temperature on Battery Capacity and Life - Engineers Edge
• Sealed Lead Acid Battery Applications - Transwiki
• GB Industrial Battery - AH Ratings: 6hr rate vs 20hr rate
• Battery Performance Characteristics - How to specify and test a battery

How much power am I using?

To know how much power you need, you first need to know how much you’re using. If you can’t measure the current your laptop uses, check the power supply rating. Also, your NiMH batteries will need to have at least as many watt hours as they store. Don’t forget to compensate for conversion efficiency.

Estimating Laptop Power Usage

Let’s say your laptop power supply puts out 19V at 4A – that’s 19V * 4A = 76W. However, it may only use that much power powering your laptop and charging its battery. If the battery is charged, assume 76 watts anyway. If your laptop actually used 60 watts, given a conversion efficiency of 85%, the actual power consumed would be (100% / 85%) * 60W = 70.6W. Running for 4 hours, that would be 76W * 4hrs = 304Wh.

Estimating Battery Charger Power Usage

If you have 4 AA NiMH batteries with a capacity of 2500mAh (2.5Ah), then 1.2V x 2.5Ah x 4 = 12Wh needs to go into those batteries. Again assuming a conversion efficiency of 85% for the battery charger, let’s say we need (100% / 85%) * 12Wh = 14Wh.

Total Usage

So, all together you’ll be using about 304 + 14 = ~320Wh a day. To err on the side of caution, let’s say 350Wh.

Where will I get my power?

It’s unlikely that you’ll have a MPPT solar power converter that will work directly for your laptop or batteries. (Although you might be able to charge 10 AA NiMH batteries in series with a 12V charge controller.) So you’ll likely need a 12V SLA (sealed lead acid) battery and a 120VAC inverter. If you bring a big enough battery, you won’t even need a solar panel, but that would be quite a heavy battery.

Estimating Battery Size

Assuming you’re using a 12V battery and your inverter has a conversion efficiency of 85%. To have enough power for one day the battery would need a capacity of (350Wh / 12V) * (100% / 85%) = 34Ah. For five days you would need 5 of these batteries or one 170Ah battery (34Ah * 5 day). But that’s about 140lbs of weight and it doesn’t take advantage of the sun, so let’s use only one with a solar panel.

Estimating Solar Panel Needed

The battery we chose can store about 34Ah * 12V = 408Wh. Assuming a charge controller efficiency of 90%, we need about (100% / 90%) * 408Wh = ~450Wh from the sun. Let’s also assume the sun will shine adequately for about 6 hours (or a fourth of the day). You’d need a 450Wh / 6hrs = 75W solar panel, or an 80W panel which is more common.

It’s not rocket science

March 14, 2010

It’s true that the necessary parts to have a usable solar/wind system are fairly expensive, but the skill required to make it work isn’t rocket science. In fact, it’s probably easier than auto repair. Probably more often than not, contractors will simply follow the available instructions. At worst, they might cut corners. If you do it yourself, you could probably save quite a bit of money while knowing exactly what you did and how well it was done.

Do the Research and Planning

Chances are you’re reading this blog because you want to know how renewable energy works and how you can use it. If you don’t know how to do something, you research it and find out from those who do. I didn’t know a thing about Tesla coils until a couple of years ago. Since then I’ve made a few.

Once you’ve developed a better understanding about how the parts work together and what they’re called, you can begin to plan. Here’s some good things to remember:

• Do your homework.
• Failure to plan is planning to fail.
• Plan your work and work your plan.
• Know your limits, (then reduce them).
• Make long term plans in short term intervals.

Consider Economic Efficiency

In some instances, it might be more economically efficient for someone else to do the work. What costs more? How much is your time worth? Let’s assume the following scenario as an example:

• You normally get paid $15 an hour.
• You estimate it would take you ~20 hours to install your renewable energy system.
• That would cost 20 * $15 = $300 of your time.
• Unless someone else can do it for less than $300, you might want to do it yourself.

The above example of course doesn’t factor in intangibles. Even if you you could find someone to do it for a little less, perhaps you would still want to do it to know how it was done. Therefore the knowledge would be worth the extra hours spent as well as the peace of mind knowing it was done properly.

Consider Electrical Codes and “Qualified Personnel”

Perhaps you watched the Enphase Micro-inverter System Installation video I mentioned in my last article. Don’t let the phrases about electrical codes and “qualified personnel” scare you. Electrical codes are good to consider, but you can find and research this information on your own.

What if I miss something?

Realize that people just like you already install their own light fixtures, ceiling fans, switches, and sockets. Be honest and ask yourself if you really think anyone has studied all the electrical codes. More than likely they simply follow the instructions. Realize also that even some of the jobs done by some “professionals” could be questionable if not disturbing.

Common sense should always be used. Always turn the electricity off before servicing something electrical. By using common sense we also understand that like colored wires are usually connected together, you need larger wire for more current or power, and they shouldn’t be hanging out in the open. If there’s something you’re not sure about, ask someone or look it up.

What if I’m not “qualified personnel?”

What makes a person “qualified?” Do you think I’m qualified even though I’ve had no formal training? Does reading blogs, watching videos, and researching what you want to do, doing it, and then gaining experience make someone qualified? You must crawl before you can walk, but you won’t get anywhere if you don’t ever crawl.

Notice the video says “all work should,” not “must,” but this is all according to who? The contractors, understandably, want to get paid. They’re licensed. The reason why they need a license is because they are in the business of installing systems for other people and therefore are liable. It’s unlikely that you will sue yourself if you screw up.

Some Personal Experience with Supposed Professionals

Preparing for a Hot Tub

At some point my dad decided we would get a hot tub. The people that delivered it would connect it, but we had to supply the wire and conduit they would use to connect it to the breaker box. (We also ran the required wiring from the main breaker box and installed the dedicated external breaker box. Understandably, they would only wire it to an available box.)

Everything sounded good, but there was something fishy. They would not connect it to a GFI (ground fault interrupter) breaker in the breaker box because the hot tub already had an internal GFI circuit breaker. (Don’t we also want to protect the people outside the tub from electrocution?) When asked why, they said because a GFI breaker in a box would always trip without reason. But what they didn’t know, I researched on the web to learn about GFIs.

Learning about GFIs

A GFI is designed to detected differences in current in both the neutral and hot wires. If a GFI circuit breaker is far from the device it’s connected to, a delay in current causes the breaker to trip when it should not. However, our breaker box would be right next to the hot tub.

Had the GFI been far away, at the main breaker box, then what they claimed would probably have been true. Needless to say, when the installers went through the trouble to bypass our GFI breaker, we connected it back like it should be and haven’t had any problems since.

Hearing From a Friend

One of my best friends used to work with a general contractor. He told me about some interesting things they did and did not do. Then there’s the issues with government and insurance contractors. If you plan to find a real good contractor, you may have to do as much research to find one as you would learning to do the work yourself.

Using microinverters for solar power

March 13, 2010

If you only plan to sell the electricity you produce back to the electric company and not go off the electrical utility grid, then the microinverter may be the most elegant solution. You use a single one of these inverters with every solar panel in the system. Simply connect the solar panel to the inverter and connect the inverter to your electrical box–only two sets of connections.

What are the benefits?

If you use a microinverter, expansion is easy. You can start with a single solar panel and inverter to have a complete grid tie system. Adding to it is almost like adding a set of Christmas lights to an existing set. The plugs and sockets are different because they’re made to withstand weather.

In addition, microinverters give the advantage of maximum power point tracking (MPPT) for every individual panel. This means shadows or performance issues with one panel won’t affect the others. If you opt for Enphase’s microinverter, you also have the ability to get detailed day-to-day, hour-to-hour statistics for every panel! Watch the How It Works video for a video representation.

Where can I get one?

Microinverters are still somewhat new and haven’t really made it to mainstream as far as solar power is concerned. The Affordable Solar Group and EcoDirect have some pretty good prices, (but their solar panels are a bit pricey). There are many places on the web to get microinverters.

The only microinverter that is currently available is from Enphase. Another is in development from SolarBridge.

How do I connect it?

Don’t be intimidated with wiring this device. If you can install a household socket or light switch, you can install this. If you can match colors and put up Christmas lights, you can install this. The instructions alone should make it very easy to understand.

If you watch the Enphase Micro-inverter System Installation video, they make it sound simple, because it is simple. But, it does take some time. Don’t let the phrases about electrical code and “qualified personnel” scare you. I’ll discuss this in more detail in another article. Check out this New Jersey Solar Installation video for some good details.

Choosing a Solar Panel

All you really need to focus on is buying a compatible solar panel for the microinverter, (unless you’re comfortable with splicing and soldering the wires of an incompatible panel). You should be able to find a compatibility list in the support section of the company’s website. Enphase, for instance, has a download section.

Connecting the Microinverter

First you generally need your inverter in place before you connect your solar panel. Run conduit up to your roof (or your panels’ location) to a junction box. Enphase prefers you to buy an AC branch “Install Kit” for $60, but you could easily get your own parts separately. Or, you could just run the inverter wires to a box and run conduit to an inside switch which would probably be cheaper, maybe $20. From there, just run wires into your electrical box to a circuit breaker. Check out Installing Electrical Conduit Systems for more details.

Connecting a Solar Panel

The inverter and solar panel will likely have special connectors. These connectors are designed to be fool proof. But if you’re an electronic hobbyist you may want to get less expensive solar panels that aren’t on the compatibility list. If that’s the case, make sure you have the correct voltage, (you might need two panels in series or parallel). To connect a panel, just:

1. Cut off the connectors from the solar panel and inverter (this may void the warranty)
2. Prepare heat shrink tubing to cover your connections by placing them over the wires (available locally at Radio Shack or online)
3. Solder positive to positive, negative to negative
4. Cover your connections with the heat shrink tubing and shrink it

Living on DC

March 8, 2010

Most of our everyday appliances and electronic devices operate using AC (alternating current), right? … It might surprise you that most appliances we use today are using DC (direct current) rather than AC. Internally they convert the AC to DC. If you’re an electronic hobbyist, you probably already know that. If you’re using a solar system with batteries, you could save by using DC directly.

Reaping the Benefits

The benefits of running things off DC directly is that you have no conversion loss. Inverters and power supplies alike have a conversion efficiency. Most conversion efficiencies lie somewhere between 80-95%. If you can reduce the number of conversions, you will come out ahead. However, it may require you to have ten 12V batteries wired in series to obtain between 110-130 volts DC. You could use a DC-DC converter, but that would defeat the purpose.

Distinguishing What Uses AC

First you need to know what you can and can’t operate with DC. You cannot use DC on anything that has a transformer on its power input. You can use these steps as a guideline to determine what can be operated using DC, but the only way to really know is to look inside:

1. If the appliance has a mechanical switch, turn it on unplugged.
2. Use a multimeter to measure ohms (Ω) across the prongs of the plug.
3. If the meter reads about 500 ohms or less, it likely uses a transformer.

Here are some things that typically require AC to operate:

• Air conditioning and heating systems
• General purpose fans and ceiling fans
• Washing machines/dryers
• Refrigerators/freezers
• Microwave ovens
• Garage door openers
• Fluorescent lights with ballast transformers
• Cell phone chargers (which are usually small wall mount transformers)
• Anything with an AC motor

Distinguishing What Uses DC

You can use DC on anything that has a bridge rectifier on its input. A bridge rectifier is something that converts AC to DC using four diodes. If you can measure around 1 meg ohm (MΩ) or more across the prongs of the plug using a multimeter, it most likely uses a bridge rectifier. Again, the only way to really know is to look inside. Most of the following items use a bridge rectifier or can use AC or DC:

• Any lengthwise oriented or switching power supply (doesn’t mount on the wall)
• Computer/Laptop power supplies
• Incandescent, CLF, and LED light bulbs or Christmas lights
• DVD players and newer VCRs
• Game consoles

Replacing Wall Transformers

One of the most pesky things to deal with are those big black and inefficient wall transformers. The output of most of these are DC because they use a bridge rectifier on the output of the transformer. If you can find a switching power supply at the same DC output voltage to take it’s place, then replace it.

Solar panel wiring

February 28, 2010

Some may think there’s a lot to know about wiring a solar system, but the truth is the basics are pretty much the same as they were 20 years ago. Wiring solar panels is like wiring Christmas lights. There are several sites out there that show you the basics. However, it’s important to know when to use the methods discussed.

What’s your input device?

Before you buy solar panels, you need to know what you’re going to use to convert the solar power. Are you using a charge controller and/or a grid tie inverter? Here’s a couple of different things you could use (click on their description tab for details):

• Kaco blue planet 1502xi Inverter
• PVPowered PVP1100-SD-120
• Morningstar TriStar TS-MPPT-45 Charge Controller
• OutBack FLEXmax 80 Charge Controller

Wiring

First, it’s important to know the basics. There are two basic ways to wire solar panels, series and parallel. Series arrangements increase the voltage of an array. Parallel arrangements increase the current of an array. Let’s use an 80 Watt, 12 Vpm, 6.6 Ipm solar panel for examples. (See my article about choosing solar panels to learn what Vpm and Ipm means.) Wiring panels in series:

• +/plus/red to –/minus/black, +/red to –/black, + to –, etc.
• Three panels in series equals 36V at 6.6 Amps.

Wiring in parallel:

• +/plus/red to +/red to +, –/minus/black to –/black to –, etc.
• Three panels in parallel equals 12V at 19.8 Amps.

For more examples and pictures, check out these sites. Keep in mind that you will likely have to use both series and parallel connections within the same array:

• Solar Energy Science Project Topics: What are PV Panels?
• Solar Energy, Power, Electricity
• Physical Computing at ITP | Notes / Solar Cells
• Learn how to wire solar panels and battery systems
• UPM Solar Decathlon 2009: Solar Roof

Series vs. Parallel

These wiring arrangements, though different, generally achieve the same result in terms of power. But there are differences you should consider:

	Series	Parallel
Electrical focus	voltage	current (amps)
Wire diameter	smaller	larger
Physical handling	easier	harder
Cost per foot	less	more
If one panel is in the shade:	the whole string produces less power	the other panels are unaffected

The device you use to convert your panels’ power will determine your wiring arrangement, or vice versa.

Direct Solar-to-Grid Inverters

Most high power grid tie inverters (for solar systems) will require many series connections of solar panels. If you look at the input specifications for the first two devices listed at the top, they require 120-400 VDC.

You’d need 25 * 12 Vpm solar panels in series to make 300V. Or, 5 * 60 Vpm panels. Notice how much current these inverters can handle, about 20A. They generally don’t need a lot of current at that high of a voltage.

Charge Controllers

Most high power charge controllers will require more parallel connections of solar panels. If you look at the input specifications of the last two devices listed at the top, they’re good for 45 or 80 Amps DC.

You’d need 6 * 10 Ipm solar panels in parallel to make 60 Amps. Or, 2 * 30 Ipm panels. These charge controllers can still handle up to 150 Voc, but they’re designed to work with higher current. They generally don’t need higher voltage like solar-to-grid tie inverters. But keep in mind that the voltage should be higher than the voltage of your battery bank.

A close look at Inverloch

February 24, 2010

I understand that a writer/artist has free reign to make a story any way they choose, especially if it’s for themselves. But as an outside reader, it’s no fun to vomit up something that tasted so good.

I suppose you could say my article has plot spoilers, but I think it’s more fitting to say my article is a plot warning. I suppose you could also say my view is “skewed” by my Christianity, but this is way beyond me: “At the end of the story, there is a main plot-twist that most fans of the comic hated” (WikiFur). The ending is hardly a plot twist as it is a plot train wreck.

My First Read of a Graphic Novel

Inverloch was my first time to read a graphic novel. To my dismay, it might be the worst. I’ve seen a lot of movies and played a few games. I admit that I haven’t read many regular novels, but I don’t think anything has completely let me down as much as Inverloch.

I don’t doubt that some people liked or even loved the story. Maybe even you figured it out before the end and still enjoyed it. If so, you’re probably missing a big part of the picture concerning prejudice and racial segregation.

I like the style and layout. I like the few numbers of panels per page and the backgrounds. I love the characters (or I did). But being deceived from the very beginning and learning the truth at the end really breaks the scales. Learning the truth is a good thing, but it hurts to learn the basis of the story is built on a lie.

The Buildup

Official Description

Let’s read the description straight from the site (also see description on Kidjutsu):

“The story of Inverloch centers around a young man named Acheron, from a horned wolf-like race called the da’kor. After a chance encounter with an elf, he finds himself setting out on a seemingly innocent mission - that of trying to locate Kayn’dar, another elf who has been missing for the past twelve years.

Meeting up with new friends and companions along the way, he quickly begins to learn that the world is not quite the peaceful place he believed it to be - embroiled with prejudice, racial segregation, and hidden danger. And the truth behind Kayn’dar’s disappearance is something none of the party would ever expect…”

Everything the novel seems to build up is essentially thrown out or never existed in the first place. Notice it mentions prejudice and racial segregation. This is built on early in the story.

Indicators of Prejudice and Racial Segregation

Here are a few excerpts (try to follow the context):

• “We have something on an undeserved reputation…” (Ch. 1, p. 9, panel 3)
• “Oh! It’s just a cute forest animal.” later followed by “But da’kor… they’re horrid and vicious monsters.” (Ch. 1, p. 25, panel 1 (&3) and p. 26, panel 3)
• “You’re… not what I expected a da’kor to be like. I mean no offence, but everyone says how brutish and ill-tempered they are.” (Ch. 2, p. 8, panel 1&2)
• “Humans and elves hate us, fear us, despise us. All that does is breed the same feelings from the da’kor toward everyone else in return. …” (Ch. 2, p. 19, panel 1 (&3))
• “Shiara… I can’t change what I am…” (Ch. 2, p. 22, panel 3)
• “Naturally, the elves decided to blame the da’kor.” (Ch. 3, p. 8, panel 3)

What makes a person?

A far as I understand, a person’s personality makes them… them, their soul, their spirit. … You’re lead to believe Acheron is a da’kor (Ch. 1, p. 9). The reality is, the Acheron you’re introduced to is Kayn’dar, an elf in a da’kor’s body (Ch. 24, p. 11±1). The real Acheron at this time is actually a da’kor in an elf’s body, Kayn’dar’s body.

Acheron’s Mother and the Other Da’kor

Did Acheron’s mother really know all along?

It’s strange that Acheron’s mother herself seems oblivious that “Acheron” is actually Kayn’dar, leading us into complete deception (Ch. 2, p. 3). She also says “You have such a kind heart, Acheron,” (Ch. 3, p. 12, panel 5), but supposedly she knows he’s not really his son. Is she trying to continue Kayn’dar’s deception?

Acheron’s mother also says “There never was or will be any other da’kor like you,” (Ch. 3, p. 13, panel 2). Well, that’s certainly true of the body anyway, the only da’kor attribute, (and maybe some memories retained by the real Acheron). But the actual person isn’t a da’kor, it’s an elf who’s name is Kayn’dar.

Where did her hopes lie?

Consider that if Acheron’s mother did indeed praise “Acheron” knowing he was Kayn’dar, was her faith in the elves? It certainly seems like it (Ch. 24, p. 22, panel 4). I don’t think it could be said that she had any faith or hope in her own kind, the da’kor.

Did she regard her real son?

We later see her “lament” her son’s brutal death: “He was always such a foolish boy…” (Ch. 24, p. 23, panel 1). The supposed irrevocable love between a mother and her child is severed. She simply dismisses her authentic son as a fool without pity. She was even presented with options (Ch. 3, p. 15), but didn’t seem to care. Even Varden sheds a few tears, for his father (Ch. 11, p. 30 & 31).

So, the elves gain leverage through Kayn’dar who is rightfully praised as Acheron’s mother admits, “I was expecting to raise a rude and conceited child, but…” (Ch. 24, p. 23, panel 2-4). Unfortunately, this way by which the da’kor could change their minds about elves, is limited to Acheron’s mother and a select few da’kor. It’s interesting to note that these da’kor initially did this to save their own race (Ch. 24, p. 23 & 24).

Acheron’s mother seems to care about the da’kor as a whole (Ch. 24, p. 24), but it seems her son was just one of the numbers, nothing special.

Parenting

Why was Acheron foolish in the first place? … I’ll let the subtitle infer what you probably thought I had in mind. However, it doesn’t seem that Acheron’s childhood was really that bad (Ch. 2, p. 13). This brings into question whether the author actually knew which direction she wanted to go.

Is there hope for the da’kor?

Maybe if the da’kor, even a few, changed themselves and stopped killing humans (Ch. 1, p. 12), they wouldn’t loose their numbers to humans (Ch. 24, p. 24). What better example could be set than one willing to risk life and limb to save one of another race, in public? Since “Acheron” traveled, his quest became known, his reputation was being built (Ch. 5, p. 24, Ch. 8, p. 19-22, Ch. 9, p. 20).

What a lesson it would be for those of other races (along with the da’kor themselves) to learn what this “da’kor” did (or could have done) to save the elves, an act of selflessness. Acheron could have corrected a misdeed of his own people. But when it’s discovered that “Acheron” is an elf, (essentially reflecting an elven personality), imagine the mindset of all the elves who are prejudice, not Kayn’dar. I can almost hear some conclude, continuing the stereotypes against themselves:

• “Oh, Acheron was really an elf. It all makes sense now. No wonder he was so kind.”
• “Acheron was really an elf? The world needs to know he wasn’t really a dreadful da’kor.”
• “Does Kayn’dar really think there’s hope for the real da’kor? He never really was one of them.”

What about the author?

The one thing that really seems confounded is the real Acheron himself, living in a elven body, calling himself Silvah. He didn’t even seem to recognize his own body. This seems to be vaguely hinted (Ch. 18, p. 7-10, p. 24; Ch. 20, p. 19), but it also enables the author to take an undecided direction, even up to the end of chapter 23. But even given that, why would he trust Neirenn, who he knows to be against (or at least suspect) him, to shout “Behind you!” essentially causing him to destroy his own body (Ch. 23, p. 23 & 24)?

Sarah Ellerton supposedly wrote the script before the drawing process. She said in an interview with Janet Houck, “The script hasn’t changed too much - the plot is basically the same…” But then she goes on to say, “The only major change I made since the first draft of the script was the ending, which was almost completely rewritten just before I started drawing.” (Inverloch’s Sarah Ellerton Tells All)

As far as I understand, usually the ending determines the conclusion of the whole plot. While most of the original script may be essentially the same, it’s meaning can change dramatically. It’s hard to rewrite the end without considering the whole. But then you’re left to wonder, what was the original ending? We may never know.

It’s interesting to note that her general inspiration seems to stem from Disney animation features. She also says, “I love simple, light-hearted fantasy stories more than brooding war-centered epics,” (Inverloch’s Sarah Ellerton Tells All). I don’t know about everyone else, but when I discovered “Acheron” wasn’t Acheron at all and his own mother lacked pity for the death of her own son, my heart fell into a pit (so-to-speak).

Driving a Wedge

The resolution reached doesn’t seem to stop or even slow the continuing prejudice and racial segregation against the da’kor or the elves. Unfortunately, it seems to compound it. In essence, the conclusion of the novel gives me no good reason to necessarily dispute the prejudice associated with the da’kor initially introduced. It’s so far from being resolved, it actually gives me a basis for it (back at ground zero).

Acheron’s father’s generation didn’t seem to change (apart from Acheron’s mother and a few others). Acheron or his brother showed no change. Is there any example for the new generation? … I think I’ll steer clear of the da’kor knowing there’s none like Kayn’dar, the elf.

My Concluding Thoughts

I’d rather Acheron had been a martyr that was the catalyst to restoring “Kayn’dar’s” memory (as it seemed) than continue the reputation of his race as an untrusted people (as in Inverloch’s reality). … This would mean a change of Neirenn’s character as initially expected (Ch. 10, p. 28).

But aye, it’s a cruel world now innit? Why else would the elf and human who embarked on Kayn’dar’s journey go steady to a life of crime (Ch. 25, p. 25)? Who’s to say Acheron’s mother isn’t really a human?

I will soon read Batman: The Dark Night Returns and Kingdom Come as part of my sci-fi & fantasy literature class. I doubt my experience will be at all bad compared to Inverloch. I know that I have also disappointed readers by discontinuing my own Set Apart series, but I didn’t destroy what I planned to build up. I admit my failure to plan properly.

Choosing a charge controller

February 21, 2010

Solar panels and wind generators produce electricity, but their output varies widely based on the available sun or wind speed. Therefore there is a need to convert that output to something a little more consistent using a charge controller.

Do I need a charge controller?

Generally, you will not need a charge controller if you simply plan to sell power back to the electric utility company. You will need a charge controller if you plan to:

• use batteries
• use an OutBack Power System (which requires batteries)
• use solar and wind power in the same system
• go off-grid, independent from utility power (usually a mobile or remote home)
• have a backup power source during outages (which requires batteries)
• power a portable inverter or otherwise large device (requiring a significant battery source)

What kind do I need?

There are almost as many different types of charge controllers out there as there are solar panels. However they all essentially do the same thing, which is charge batteries. The most common battery type used is sealed lead acid (SLA) or gel lead acid, which is very similar to SLA. Click here to see more.

If you plan to use wind generators, the charge controller is usually built into the unit or comes with it separately. Therefore, you don’t need to worry about choosing a charge controller unless you plan to make your own wind generator.

What you need is largely based on what you plan to power and how often you plan to use it. In my article about choosing solar panels I discussed calculating power:

• V (Volts) * A (current in Amps) = Power (Watts)

Keep in mind that the sun is not always shining and you’re probably not always using power. I will discuss how you can calculate your specific needs in a later article. There is a little math involved.

How do I connect it?

Connecting a charge controller is fairly simple. There are usually two things to connect, sometimes three. You will always have to connect the solar panel(s) and the batteries. The labeling is fairly explicit. Consider these and look at the pictures:

• SunGuard 4-12V charge controller
• Prostar 15, 12/24V Charge Controller
• OutBack FLEXmax 80 Charge Controller

Notice the Prostar 15 had third thing called “load.” A load is what you plan to power. Instead of connecting something directly to the battery, the charge controller should turn off the load when the battery runs low. Most inverters do this automatically.

Don’t be intimidated by the FLEXmax. It also has two simple connections, PV +/- and Bat +/-, it just requires larger wire. The FLEXmax is generally used in larger solar systems.

Wiring details should be outlined in the instruction manual for your specific charge controller. I’ll try to cover wiring in more depth at a later time.

Will incandescent lights die?

February 20, 2010

There’s been a lot of advancement in the field of lighting, particularly solid state lighting with LEDs, but that doesn’t necessarily mean incandescent bulbs will phase out. Consider that they were probably conceived as a way to replace candles, and they excel at that, (heat and light). Also, candles haven’t phased out.

Today’s Applications

Incandescent lights still have a place in the modern world, but not necessarily as a lighting source. They produce light, but most of all, they produce heat. Here are some modern day applications:

• Heat Lamps (more examples here and here)
• Reptile Heating and Lighting (more examples here and here)
• Incubation (more examples here and here)
• Easy Bake Oven
• Scentsy (a flameless scented candle)
• Plant Grow Lights

Give Me Heat!

It’s been said that only 5% of the energy going into incandescent light bulbs results in light. 95% of that energy results in heat. I see no reason to refute this, they get hot! Now that’s efficient… for heat production.

Other places where people would prefer incandescent bulbs over the newer bulbs would be in cold locations or climates. If you move from Texas to a northern state, you’d probably prefer more heat. If you’re working outside on a cold winter day, those hot halogen work lights feel pretty good.

What about the Energy Independence and Security Act of 2007?

Some might be concerned about the federal bill that phases out incandescent light bulbs between 40 and 150 watts. (See Subtitle B, Sec. 321 in the full text.) However, there seems to be enough exceptions that a simple relabeling could probably circumvent such restrictions. Just because “incandescent light bulbs” may not be sold doesn’t mean “heat bulbs” can’t be sold.

Then there’s the burning question of “who is the government to dictate what bulbs I can’t use?” I find it particularly disturbing that the government would do this (among many other things). But, I look forward to LEDs being used in lighting applications, because you get more light per watt of energy.

Reusing the CFL circuit base

February 18, 2010

For you hobbyists out there wanting to reuse the parts from a burnt out CLF (compact florescent light), there are some ways to reuse the circuit in the base. With a few steps I’ll show you how to wire up a small florescent light to take it’s place.

Know what Failed

CLF lamps may fail because the filament in the bulb burns out, just like regular incandescent bulbs. If this is the case, the bulb doesn’t produce any light. If the CLF filaments at the base light up, but the rest of the bulb doesn’t, the electronics failed. This means you could use the base of another broken CFL to repair it.

Open the Base

First you need to get it open. Some are fairly loose and you can easily use a flat tip screwdriver to pop it open. You might have to use a hacksaw on others and then use a screwdriver. Be careful not to break the bulb.

Get to the Circuit Board

Once you have it open, just lift out the circuit board. Next, cut off the wires from the bulb at the circuit board. If you had to use a hacksaw, you may have to cut the wires from the bulb first and then pop out the plastic ring you sawed off.

Get a Bulb, Wire It Up

You saw two wires coming from each end of the bulb, right? Now, just get a small florescent light (like one found in a modern camping lantern) and connect it the same way as the other bulb was connected. At this point you probably realize that a compact florescent light is simply a florescent light.

Turn It On

Once you have everything connected, turn it on and see if it works! Assuming your bulb is good, there shouldn’t be a problem and it should turn right on. Be careful not to shock yourself!

More Experimenting

Try some different types of florescent bulbs and see what works best. Try some in series. Just keep in mind that the filaments at the ends shouldn’t be brighter than the rest of the bulb. They also shouldn’t flicker. If you observe this, you may be using excessive power to light the filaments than the whole bulb requires! Try a smaller bulb.

Is it on, off, or idling and how to tell

February 17, 2010

I’m sure most of you have heard or read that some appliances still use electricity when they’re “off.” There is no doubt this is true, but how can you tell? Identifying what’s idling and what isn’t (without paying money for something like a Kill A Watt Monitor) is a good first step.

How much energy is really being wasted?

An idling appliance is something that uses electricity when it’s “off.” When “off,” they could use anywhere from about 5 to 25 watts. Usually these appliances have internal clocks or settings. Unplug the appliance if you don’t care to keep time or settings you may have saved.

A disconnected cell phone charger, laptop power supply, or any external power supply not connected doesn’t need to be plugged in. Depending on how they work, they could use anywhere from 0 to 10 or more watts.

Here are the results (in watts) of some measurements I took:

• Nokia cell phone charger (not connected):
  0W
• Laptop power supply (not connected):
  2.5W
• Ethernet router power supply (not connected):
  8.9W
• Cassette deck, “standby” (it’s not labeled “off”):
  2.5W
• VCR/DVD player, no clock, completely “off”:
  5W
• Older PlayStation 2 turned “off” from the front button:
  6.3W
• Older PlayStation 2 turned off from the back switch:
  0W
• Computer, completely “off”:
  10W
• Older VCR with clock, completely “off”:
  13W
• A Sony stereo system with disc changer, cassette deck, and clock, completely “off”:
  25W

How can I tell if something is idling?

Common Indicators:

• Lights or a display is still on and working
• It hums or makes any noise when you put your ear right up to it
• It can automatically turn itself on (as through a timing function) if it’s “off”
• It is warm to the touch due to power dissipation

Typical Appliances that Idle when “Off”:

• Desktop computers made after 1995 (or after ATX was introduced)
• Laptops
• Computer monitors and TVs
• VCR/DVD/Blu-ray players
• PlayStation, Xbox, Nintendo, and other gaming systems
• Satellite receivers
• Cell phone chargers
• Answering machines
• Anything that has an external power supply
• Anything that keeps time

Push-Button Switches

Another way to tell if an appliance is idling is by the power button or switch. If the power button is small and requires a gentle push with a subtle “click” or “tap” sound, it likely idles.

If the power button feels heavy duty, making a “click-cling” or a “click-clack” sound, it probably doesn’t idle. This is because these switches usually switch the wires straight from the power cord. It’s the equivalent to unplugging it. This is common in much older appliances, especially stereos and amplifiers.

Toggle Switches

If you have an appliance that has a toggle or flip switch like a power strip, it probably doesn’t idle. However, if the switch is small, thin, or light, it might use idle power.

Too Much Hype?

Another point I want to get across is don’t be too optimistic. Most idling appliances use very little electricity. Also, new power supply designs continue to increase in efficiency during idle time. Consider that a laptop or cell phone also uses idle electricity when it’s completely “off” (unless you have no battery).

Air conditioners and heaters make the meat of your electric bill, not idle power or lighting. Unplugging any one appliance will probably make a negligible difference. It’s when you have several that they have an impact.

Turning off a power strip to everything you’re not using is a good idea. Even the Smart Strip uses some idle power. If you’re still using any incandescent light bulbs, you’ve got a slightly bigger problem than idle power.

Choosing solar panels

February 16, 2010

There’s a lot of different solar panels out there, and with so many choices, it would be helpful to know what to look for when buying one. I’m going to explain some of that technical jargon. This way you can better understand how or what panels to use with a given system.

Understanding the Spec./Data Sheet

Let’s say you want to check out a specifications sheet for a solar panel, like this one or this one. As you start looking at the tables, you’ll see terms like:

• Polycrystalline silicon (or Multi-crystalline silicon)
• Monocrystalline silicon
• Open Circuit Voltage (Voc)
• Maximum Power Voltage (Vpm) (or Optimum Operating Voltage)
• Short Circuit Current (Isc)
• Maximum Power Current (Ipm) (or Optimum Operating Current)

If you’re viewing a solar panel product page and can’t find Voc, Vpm, Isc, and Ipm, you should be suspicious!

(As we discuss these terms, keep in mind that voltage and current measurements are usually taken under a consistent test light source. The results should be comparable to good sunlight.)

Vpm and Ipm

These are the most important aspects of the solar panel because they determine power. Both Vpm and Ipm are the ideal maximums at which the solar panel functions. Looking at Ohm’s Law, we know that:

• Vpm * Ipm = Power (Watts)

If you multiply Vpm and Ipm and don’t get something close to the advertised wattage, you should be suspicious.

This may seem trivial and basic for some of you, but the point is that you need to know what is being advertized. What is a “12 volt” solar panel? Is it 12 Voc with about 9 Vpm? Or is it 12 Vpm with 18 Voc? I admit, it’s usually the latter, but you need to make sure.

MPPT - Maximum Power Point Tracking

Both Vpm and Ipm establish the maximum power point. When you see a charge controller or grid tie inverter, they may advertise a MPPT (maximum power point tracking) feature. All this means is it searches for Vpm and Ipm to get the most power from your solar panel(s).

Voc and Isc

Consider Voc and Isc as the opposite extremes of Vpm and Ipm. Generally, you don’t really need to worry about these. You won’t get any power output at these extremes.

Open circuit voltage, or Voc is the voltage measured when the panel isn’t connected, hence “open circuit.” Short Circuit Current, or Isc is the current (amps) measured when the panel is completely shorted, positive to negative.

Poly-crystalline vs. Mono-crystalline Silicon

This makes up the composition of the silicon used in the solar cells of a panel. Silicon is the same material that make up computer chips. You don’t really need to worry about the raw materials that make up a solar panel. But for your interest, here are some key differences:

Composition	Cost	Efficiency	Appearance
Poly-crystalline	less	less	usually rectangular or square without rounded corners
Mono-crystalline	slightly more	slightly more	usually square with rounded corners