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.