I just signed up for a solar...rental service? I think that's what they are anyway. They are called CitizenRe (if you decide to sign up for them then let them know if I referred you, I get a 5% discount on my service for each referral!). For a $500 deposit (refundable at the end of the contract) they will determine how much solar power is needed and will install the whole system - for nothing more than the initial deposit. I'm not quite clear on all the details yet because I *just* signed up about a half hour ago, but they claim that all you have to pay is what you're paying for your monthly electric bill (as a rental fee). So I'm not saving any money - at least I won't have to front the money for the initial setup (which can be $30-40k) and I'm doing something good for the future of my son.
I'm pretty excited about it and will update as I learn more. I got my alternator bike built and will post pictures and other tidbits of information in a bit. I've got to keep up with the Begley's!
Now that I live in the land of sunshine I'm becoming obsessed with solar power and heating. I have a plan to turn the (detached) garage to full solar power. The main reason is because back when my house was built it was okay to dangle three bare strands of wire from the eves for power between the house and the garage. One accidental touch to those wires with a piece of metal could be disastrous, I almost found out firsthand with the pool utility pole. Oops.
First I determined what I needed to power:
1) a beer fridge
2) a table saw for limited intervals
3) a 13W light we keep on 24/7
4) a garage door opener
Next I needed to figure out what the power requirements are for these items are individually and what the power consumption would be with the two most power hungry devices on at the same time (table saw and the beer fridge, a highly potential scenario). Here's the figures I came up with:
1) 7.5A * 115V = 863W
2) 15A * 115V = 1725W
4) Couldn't find any label with power consuption information on it - and it's OLD (says it's an Ambas-a-door...?)
The next thing I needed to do was to figure out how to take this information and to translate it in a way that would tell me how much solar power I would need. I searched and searched for something that would help me with the calculations but all I could find is information on converting your whole house using the information from a power bill that shows average kWh consuption. I just moved in about two weeks ago so I don't have that information available AND I don't want to convert the whole house anyway. Finally I found a web site that provided just enough informatin on how to calculate the daily solar needs of an individual appliance. I have provided how to calculate this below:
1000W = 1Kw
6 minutes = 1/10th (or 10%) of a kilowatt hour (and 10% of a clock hour)
If a 1000W device runs for 6 minutes, then:
1Kw * 10% = 0.1kWh (1 * .10 = 0.1)
EXAMPLE: (Assuming a refrigerator runs 12 minutes an hour, which seems a reasonable estimate to me)
Refrigerator - 7.5A * 115V = 862.5W
863 / 1000=0.863 of a kilowatt
12 minutes an hour = 20% of a "kilowatt hour" (and 20% of a clock hour)
.863 * .20 = .1726kWh
Hopefully that all makes sense. Sorry if I over-explained or under-explained any part of it, I hate searching for information and ending up on a website that has what I'm looking for but I don't have enough experience or information available to understand it. Let me know if either of these are the case here.
Now that I have that figured out I can finally determine how many solar panels I need and how big of an inverter I need. If the beer fridge runs for 12 minutes an hour and consumes 0.1726 kilowatts each hour then it will consume 4.08Kw in a 24 hour period (NOTE: this is only an estimate of how long it will run each hour - I need to do some tests to estimate the actual hourly run time). If I run the table saw for 6 minutes a day (keeping it to multiples of 6 to make the math simple for me) it will consume 0.173 kilowatts each day. The 13W bulb will consume .312 Kw a day (.013 an hour * 24 hours). The garage door we'll just forget about right now since it's used only once or twice a week for about 10 seconds a shot. If we add up all the figures then I will need to capture 4.565Kw a day (4.08 + 0.173 + 0.312).
Most sites I've gone to estimate the general average "prime sunlight hours" per day over the course of a year is 5 hours a day. Those are the hours that a person can expect to get the most generation out of the panels. Obviously it's going to be more hours in the summer and less in the winter. Another factor to consider is the efficiency of the panels and the DC to AC converter. I've read several places that it's a good assumption that the panels will produce 10-20% less power than they are rated for, so I'll use a 15% loss assumption just to be on the safe side. The panels I'm hoping to get are rated for 115W
Here's more math for you. 115W * 5 hours = 575W. Adjusted for the 15% potential loss (575*.85) is 488.75W a day (prime hours). So...4565W needed a day, devided by 488.75W a day from each panel means I need to get 9.34 panels. Eeesh. I don't think my wife will let me do that :). I'm going to need to insulate the hell out of the beer fridge and put it on a timer so it only runs from late morning to early evening!! *breaks out the calculator again....
Okay. If I run the fridge from 10am to 7pm then that changes the power consumption of the fridge from 4.08kWh to 1.53kWh a day (again, this is only an estimate at this point). That drops the overall daily power requirements of the garage down to 2.015kWh (or 2015W). That's a *little* better. 2015W devided by 488.75 per panel means I'd need 4.12 panels. I'm trying to get it down to 2 panels somehow...without sacrificing the icy coldness of the beer too much. I'd say I've got a challenge on my hands. I'll update as the project matures a little.