Sunday, January 31, 2010

Mystery Of Power

I have a confession.  I truly have a desire to learn about alternative energy and how to actually make it happen. I have tried and tried to read and learn about it but nothing seems to sink in. I needed an offgrid  Power For Dummies lesson.  I was talking about this in the APN chat (aka Wolfe's Den) with a friend who is quite savy about the subject.  Imagine my surprise and delight when I read this!  I think I actually "get" it so far but will have to wait for part two to see if I am just delusional or what!  Thanks Kronic!

Mystery of power

So you need power? Lets go over a few things to help you decide if living off the grid can work for you. First things like your electric clothes dryer are not going to be possible unless you have a very large bank account to work with.
With any solar or wind driven system it works basically like this. The sun on a solar charger and the wind in a wind driven system charges a battery rack. That’s all it does, it does not power your house. Only very large system can do that and its far out of most peoples reach cost wise. So why do we want this and can I make it work? The answer is yes we can make it work.
Step one is decide to make a commitment to live a different life style, you don’t have access to the power company so your on a fixed amount of power. I’ll try arrange the steps to make it simple and easy to understand, I do tend to get a tad geeky so ask questions.
Step #2
Ok you have made a decision so lets go. First look at your location to see which form of power better suits you. Do you live in a desert like humble, if so then solar is a better choice as most days are sunny and bright. In other areas wind may be a better option as there may be wind many days out of the year. Basically we are trapping the energy the sun or wind provides and converting it to electricity for our needs. If possible its always better to have both sources, so if its cloudy and stormy the solar wont work but more than likely the wind will compensate.
Lets decide how much power you really need, note I said need not want. It can take up to 20 Killo watts to power a complete household, that would cost you a years wages at best. So we will look at ways to cheat, yes cheating is ok in power conversion. Lets look at lighting, its simple, turn switch and bulb comes on, but how much power do we need for a bulb? The answer is too much, we can not afford to waste what we have so lets cut our needs. Cutting our needs does not mean doing without. Our systems are designed to collect and store 12 volts. The reason is it’s a standard its easy to fabricate and easy to adapt to our needs. Since we have 12 volts lets think about this, the items like lights and tv’s and microwave use 110 not 12. So if we want to use them we need to convert our power to 110 or convert our appliances to 12 volts. Things like lights are easy we can get 12 volt lights and even 12 volt LED’S so we don’t need to convert for them. Don’t forget LED uses a lot less power than a filament bulb and that’s good. Oh LED stands for light emitting diode. The primary reason we want to use as much 12 volt items as we can is because converting 12 volts to 110 is very ineffective, we will waste a lot of power doing so.
There are refrigerators and microwaves that use 12 volts, any thing we can get in 12 volts we want. But even at 12 volts the consumption still needs to be watched, we don’t have unlimited power. Now we move on to the geeky stuff, I hope your eyes don’t glaze over.
Ok a battery is rated two ways, one is CCA or cold cranking amps the other is APH or amperes per hour. We are not concerned with CCA as we will be slowly pulling power over an extended time, so we want the greatest APH that we can get. There’s many types and styles of batteries but in truth there’s only 4 manufactures that make lead acid batteries. There’s also nickel cadmium and a host of new batteries you could choose. But we want simple, effective and , most of all we want longevity. On my system I chose a battery called an Odyssey, even though they are very expensive you will need fewer of them and they have a twelve year military design. No car or marine battery can offer this.
I chose the Odyssey PC2250, now it does have an incredible CCA of 2250 amps but as stated above we are not interested in that capability, we are how ever very interested in fact its reserve capacity is 240 minutes at 25 amps. That means without being charged it can deliver 25 amps for 240 minutes. Now 240 minutes may not seem suitable to power stuff as there’s 24 hours in a day. But if we use our heads we will never need that much amperage. A LED in every room to light your house would use depending on LED you chose as little as one amp for the whole house. Now that 240 minutes just went way up as we wont be using the whole 25 amps. And if you use multiple batteries you add 240 minutes for each extra battery you use. But we cant just use 6 batteries which would be great but an average solar panel cant charge that many at one time. So we use less batteries or we use more solar panels and bigger wind mills. There’s a fine balancing act we need to get to, so that we have what we need but also can afford to build the system. Remember the converter I spoke of? it’s a transforming system , it takes 12 volts and converts it to 110, now this is great as some things can not run on 12 volts. But there’s a down side, in creating the 110 volts we generate a lot of heat, you need to know why heat is bad. We want to work with electrical energy not thermal (heat). So as we convert to 110 a lot of our free power is wasted creating heat, that cant be helped, it’s a side effect of the conversion. So we only want to convert as a last resort. Ok on to more geekness (sorry sfc).
Lets talk about a converter for a bit there are two kinds one is a pure sine converter and other is a modified. SFC don’t blink and scream its really easy. We often don’t realize there’s what’s jokingly referred to as clean and dirty power. Most things we use like toasters or skil saws don’t care, dirty is fine, in other words the modified is perfect for them. But there are a few critical things we need that cant operate with out clean power of pure sine, and your using one now. Yep you guessed our computers need a pure sine or very clean power. As do televisions and most stereos. So if you ever want to use a computer or other electronics we need that pure sine if it cant run on 12 volts. Now the difference is pure sine converters are about 50% more money so we only want exactly what we need. Lets say computer uses 300 watts (most electronics are watt rated not amps) just different kind of measure. And our television uses 300 and stereo also 300, we know if we use all 3 at once we need a 900 watt inverter. Oh its fine to use two inverters, we will use the dirty modified inverter to power things that don’t care if powers clean. A lot of things like drills and saws are rated in amps, so we need convert amps to watts, why you ask? Because inverters are rated in watts so we need to know how many watts we need. Lets say under normal use, you add up the things you need to get total number of amps you need, every thing has a amp rating on it. Look at your trusty black and decker drill , it will state how many amps it uses. Ok go wonder around your house and look at things , now remember we can run them at different times so we don’t need a maximum of them all added up. I take the highest one which is a refrigerator and double it, that’s my wattage I need. Things like hot water heaters and clothes driers we wont be running as the power requirements are way beyond practical for us. Unless they are gas. Oh yea to convert amps to watts we use the equation, watts =amps x volts as an example 1 amp at 110 volts is 110 watts.
Ok that’s enough for now, go look around at things you need to power, write them down so you can get a idea of what we can do. We will go over the generators later, solar or wind, even gas operated 12 volt generators are easy to make and work well in a pinch. If we have gas to run them.
SFC you can wake up, class is over hon.


  1. SFC, I think you and I are a lot alike. This is a really good post, but I was kind of glazing over by the time we got around to #5. I am a very hands-on visual type and I need to see things for them to stick. I will bookmark and refer back often.

    I would like to get a small solar setup for The Home Place, but I'm starting to like the mood-inducing candles :-). Everybody needs a little romance now and then. Let's go solar shopping together? I hope you are well these days.

  2. I'm the same way Ginger...If I can see it I can grasp it. That's why I thought this was great. I get lost about #5 as well but I'm pretty sure Kronic will be good on the follow-up. He knows I am easily distracted! LOL As for shopping... it on G/F

  3. I also prefer visual and hands on learning, one of the things I did when I first moved off grid was to make a diagram of how our system is set up, you can see it here:

    Hope it helps

  4. gotta agree with you all eyes glazed before #5. I either need to see it and go through the whole thing a couple of times or I just need to not worry and plug it in! My husband is an electrical engineer and he talks volt, watts and kilowat hours and my eyes cross. I'm thinking this might be beyond me. I think it's important to understand though, so I'll keep trying.

  5. Great post. I'm planning a solar set up for my van.

    See Ya