Posted: 5/30/2008 12:09:06 PM EDT
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Another thread in the TexasHTF prompted me to take another look at going the solar/wind route while using the grid as a battery... According to the AEP Distributed Generation guy, they have to install some sort of electric rectifier voodoo to the tune of $5,000-$8,000 PER kW. 20 to 25 grand just to use them as a battery? No fucking thanks. Lead-acid batteries are alot cheaper than that. A few wind turbines to get away with using a smaller battery setup at night... So how doable is this? I've been looking at various plans for building wind turbines and the math involved. At about 7mph, an 18ft turbine will reliably generate ~100 watts. That's factoring in ~30% efficiency. I don't know if I can build a turbine that efficient, but the literature I've been reading seems to indicate that a home-build of that efficiency is very possible. Yeah, 100 watts doesn't sound like much, but the energy generated increases by a factor of 8 with double the windspeed. So they would actually generate alot more electricty during the day than that 100 watt reliable figure. So how much would a total setup cost me if I did say, 4 kW in solar and five home-built 100 watt turbines? How much would 3kW battery capacity cost me? What sort of electronic control equipment would I need and how much would it cost me? I assume that I'd need some way to convert the electricity back into A/C from the D/C batteries... What other equipment will I need and how much will it cost me? And yes, I do believe I can build that many functioning wind turbines. I'm currently building a small cnc router. When I finish building that, I'll use it to build a larger cnc router table capable of carving all my turbine blades. Bass ackwards way of doing things? Maybe... For info purposes, I know only the basics about electricity... Any education ya'll could throw at me would be much appreciated. -Andy |
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going off the top of my head when i was looking for a UPS for our eqiupment at work. You will need some type of converter to go from DC to AC you will need some type of monitoring equipment to swich from On the Grid to Off the Grid and back when your batteries get low. you will probably want some type of enclosure for the batteries and ventalation system to vent the hydrogen. you will also probably want to Sell your excess too. maybe some PV cells since youre in the more sunny part of the US? im sure theres more, but from my limited understanding of going of the grid. |
And, when you think about it, selling back to the grid is in a way nothing but a big battery. I believe you still would want your own backup in case the grid goes down (ice storms, whatever), but for day to day use, selling back to the grid and drawing from it at night has some advantages. You have less financial investment in energy storage, and you minimize energy inefficiencies inherent in any storage system. |
The problem with connecting to the grid is that AEP charges you $5,000 to $8,000 PER kWhr in equipment and installation to do so. Thats $25k to $40k in addition to the probably $20k in solar panels and whatever additional equipment. A 1kWhr deep cycle battery goes for ~$225, from what I've found so far. And if you only cycle them down to 50%, you can get many years of use from them before needing to replace. If you only cycle them 20%, you probably wouldn't need to replace batts for at least 10 years. Also, with some decent wind setup, you can slow the discharge of the batts and either get an even less complete cycle or the same cycle with fewer batteries. This option has the advantage of Texas exempting wind/solar generators from capital improvements for property taxes purposes. So which is cheaper overall? I don't know. I'm going to do some serious price searching and number crunching. I'll report back here with what I find. |