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Old    David Williams (wakeworld)      Join Date: Jan 1997       07-26-2010, 2:21 PM Reply   
I have been looking at solar generators lately and I was thinking about getting one to power a portion of my house. I'd probably put it in my office and power all my computers and WakeWorld junk off of it. I thought it might be a good way to cut into my power bill and also have an emergency electrical supply on hand. I was looking at http://www.mysolarbackup.com/, but I'm sure there are other options out there. Has anybody done research on these?

I can't afford a whole house system and they don't work when the power is out (unless you pay even more for a battery bank), so that's not an option. Any feedback is appreciated.
Old    Akadirtbikingdad (wakeboardingdad)      Join Date: Aug 2008       07-26-2010, 8:47 PM Reply   
David, solar has a very long way to go, but if you live out west, at least you are ahead of most area's in this country. Well, in two ways. One, you have higher priced power and more hours of sun. I work for a utility company and I have designed/installed a 12kW (12,000 watt) solar installation. The main difference with our was that it was grid tied. The one you are looking at a off grid installation. This means it is for emergency and whatever is attached to it, will have to be "unimportant" for day to day usage. Lights, fans, laptops (with their own battery backup) or some other unimportant device because when it dies, it is dead. You'll have to plug it in somewhere else when the battery dies. Here's the deal: The website states that it is rated at 1800 watts peak. That means the inverter is good for 1800 watts, but what you have to ask is this: How long is the battery rated for? What is it's amp hour rating? Looking at the size of the battery, It is not very big, therefore, it is not going to last long at 1800 watts. I seriously doubt it will last an hour or even 1/2 hour. However, if you are more realistic, say you want to run some thing that is about 100 watts, it may handle that. Here's another thing. The solar panel is only good for 90 watts. This is the highest output this panel can have and during the optimum solar lighting. That means, cloudless skies (and no shade) and perfect sun angle. Also, the panels generate the most when it is cold.

As I said earlier, in my area, grid tie is the way to go. The reason is because TVA has a program in place called "Green Power Switch". You buy and install the apparatus and they pay you (basically for what the system generates) twice the $ per kwh as they sell it to you for. Another reason is because the power is cheap. Your utility (or supplier) may have something similar to TVA's also. There use to be some good tax breaks for solar too, but I cannot remember if those are still available.

Here is the very bottom line on solar. At least where power is cheap, like where I live, you have to do it because you want to be green. It is not cost effective even with "solar kickbacks". Check this website out: http://www.bigfrogmountain.com It has some handy tools and more information that you may find useful. I got all my information, for most of my design from a website like this. There are other folks who have good websites for off grid installations. Many use regular inverters, like you use in cars or motor homes. While they may not be as efficient, they are much cheaper than what you are looking at. Many use acid type car (trolling motor) batteries, however a gel cell would be better. If your roof is facing south and is not flat, you could mount a 200 watt panel there easily and do the other things I just described for a lot less money than $2200.

I hope I have helped, if you have any other questions, PM me and I'll try to answer them. I answered another thread some time ago, but I could not find it.
Old    David Williams (wakeworld)      Join Date: Jan 1997       07-26-2010, 11:43 PM Reply   
Wow, thanks for all the info. I'll check out those sites.

I've looked into the "on the grid" solutions before and I believe in my area that you can only sell back as much electricity as you use and they buy it back at the same rate at which they sell it. However, that was a while ago. Plus, when you're tied into the grid, you don't get any emergency backup at all. When the power goes out, your solar is useless.

My reason for doing this is mainly to have some emergency backup, and the fact that it's portable is a nice bonus. Using it to power a few things in my house when it's not being used for an emergency would just be a nice way to pay for it. Call me crazy Larry, but at the rate this country is going, I see much higher electricity prices and more frequent outages in our future. I'd like to get my feet wet in this area, so that I'm prepared before that happens.
Old    Jason G (jason_ssr)      Join Date: Apr 2001       07-27-2010, 6:02 AM Reply   
Its funny you posted this, as I was looking for something similar last week. Im on the opposite end, as I had the idea based on the fact that I have access to a large decommissioned telecom battery bank. Anytime I come accross free odds and ends, I start thinking about what I could use it for and is it worth acquiring (the wife tends to frown on filling the garage up with "good intentions", especially ones that arent easily moved).

Knowing nothing about batteries, and only a general homeowners understanding of electricity, what info would I need to know to determine how much this bank would power? Obviously not portable, what else would one need to wire this into the electrical panel in the garage?
Old    Akadirtbikingdad (wakeboardingdad)      Join Date: Aug 2008       07-27-2010, 6:27 AM Reply   
The electric industry will have to change. People will have to understand that there will be a premium price to pay for peak power usage, which is called "Time of Use Metering". When that happens, the overall peak will be reduced somewhat. The reason this has to occur is because power suppliers cannot continue to build generation just for the peak of the day. It is the peak generation supplements that cost so much and it is kind of where the private sector steps in and build generation to sell it at a premium price. Most of those units are powered by natural gas too since they can ramp up to full power very quickly and then off again. As we all know, natural gas went through the roof several years ago. I also was a project manager for a fuel cell installation (only 5kW) that was natural gas powered. Ultimately, it was a flop. The gas powered fuel cell just cannot accept any type of gas. However, they work fine for hydrogen.

Getting back to your "problem" WW, if you own a "regular" house, you'll never generate more than you use. If you have regular appliances and AC. It is almost impossible. The 12kW installation I did which was most of a roof for a medium sized green house was almost $80K, but it was sweet. This 12kW is the peak load of the "typical" home. Yes, this would allow some "profit" each month, due to sell back, but it just does not make financial sense to do so. This roll around power plant is the same. It cannot be justified monetarily but can be justified for peace of mind.

ssr, you'll have to dig up the rating of the batteries. I do not do this all the time, and it was some time ago that I sized my battery power for my dirtbiking enclosed trailer (where I have a microwave) However, let's say your batteries are rated at 20 ampere hours. This means this battery can supply 20 amps for an hour. If you have 10 of them, you are at 200 amps per hour. Suspecting your batteries are 12volts, this would yield 2400 watts for an hour or 2.4kW. For lighting and minor appliances, that is pretty good, however, for large appliances, that is bad. To put that into perspective, you could run a 100w bulb for 24 hours. One thing I am not considering here is the age of the batteries, voltage degradation and losses in the inverter. That is why many "off-grid" folks use 12 volt appliances. Less losses. If you choose to use an inverter, you simply size if for your max load. If your microwave is 700 watts, get a inverter that is good for 800 or so. You may want to even get a couple of inverters. One for small loads, like 150watts, and then one for the larger load(s). It would not make sense to run a 850w inverter for just a 50 watts of lights, due to the increased losses of the larger inverter.
Old    Jason G (jason_ssr)      Join Date: Apr 2001       07-27-2010, 7:22 AM Reply   
Its a string of 12 of these in a rack. Can you translate it into english? 5 years old.

http://www.battery-usa.com/Catalog/NSB170FT.pdf
Old    "G" (grant_west)      Join Date: Jun 2005       07-27-2010, 8:53 AM Reply   
Mike Ski is in the Solar Business Holla at him
Old    Akadirtbikingdad (wakeboardingdad)      Join Date: Aug 2008       07-27-2010, 9:39 AM Reply   
Here's a link to help you out. http://www.cdstandbypower.com/produc...lated/7525.pdf Here they are using 12 volt batteries. In your case, you would series up 8 at a time to make the equivalent.... actually getting 14V nominal from the batteries you have at 1.75V each. Then you parallel each set of 8 to increase your capacity. You want to make sure you get the correct charger. I do not do this all the time. However, if you look at the ratings in the lower right hand corner, it indicates the number of hours your batteries can supply for a certain load at a certain temperature. When you place them in series, your supply voltage will increase from 1.75 to 14V, but your capacity will not change. When you place them in parallel, your voltage does not change, but your capacity does. It doubles for every for every "bank" you have. So, for a 135 watt load, if you had 4 banks of batteries, or 32 total, you could run this load for 8 hours. Or, looking at the chart again, a 600 watt microwave for about an hour straight. I think that's about right.
Old    mojo            07-27-2010, 11:45 AM Reply   
average installation is 100$ sq. ft. usually takes about 5-8 years to recoup costs, but then you either don't pay for power or sell left over back to the grid. cells typically last 30 years.
Old    Jason G (jason_ssr)      Join Date: Apr 2001       07-28-2010, 8:25 AM Reply   
Thanks fo the info! I guess Im trying to determine if bringing this rack to my house is even worth it. I would have to buy an inverter and charger so do these batteries hold enough juice to even bother? Lets say I wanted to run a couple of lights, fans, and a TV. Does this 12 battery rack give me 5 minutes or 24 hours? Ballpark? These batteries are about $550 each so i would assume the rack of batteries would be the bulk of the cost of a backup system.
Old    RileyBangerter (steezyshots)      Join Date: Feb 2008       07-29-2010, 2:19 PM Reply   
I know that it has something to do with the sun.. hope that helps

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