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Guesstimate my solar power potential

by Pengwuino
Tags: guesstimate, potential, power, solar
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Dec15-11, 12:50 PM
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Quote Quote by Ivan Seeking View Post
35 KWHrs per day over say 6 Hrs effective, is 5.8 KW. Then factor in additional losses due to angle and temp, and system losses after that.
Sadface. I read that systems are around $7/W. So that's like.... ridonkulous.
Ivan Seeking
Dec15-11, 01:00 PM
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Quote Quote by Pengwuino View Post
Sadface. I read that systems are around $7/W. So that's like.... ridonkulous.
I would take a hard look at getting a deal like Chi has, where you pay a fixed amount every month and have a complete system.

Obviously the negawatt [saving energy] approach is the place to start. You guys are total power hogs.
Ivan Seeking
Dec15-11, 01:05 PM
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You are probably a slam dunk for a passive solar heater for your water. The ROI on that would probably be good.
Dec15-11, 02:14 PM
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How about one of these beauties, Geothermal heat pump, good for heating and cooling, high tech solution, and we love high tech (affordable) solutions now, don't we ?!
The geothermal pump systems reach fairly high Coefficient of performance (CoP), 3-6, on the coldest of winter nights, compared to 1.75-2.5 for air-source heat pumps on cool days.[5] Ground source heat pumps (GSHPs) are among the most energy efficient technologies for providing HVAC and water heating.[6][7] Actual CoP of a geothermal system which includes the power required to circulate the fluid through the underground tubes can be lower than 2.5. The setup costs are higher than for conventional systems, but the difference is usually returned in energy savings in 3 to 10 years.
Dec15-11, 02:39 PM
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Earlier in the thread I think it was Ivan who said that solar panel costs were decreasing rapidly, and I'd have to agree with that. I'd hold off for at least the next couple of years and see what kind of potential the market has. I would be hesitant about installing a large panel or set of panels unless California offers to buy energy from you. Meaning that you connect the panels to the grid and any power that you can't use goes to into the grid.

Up here in Canada we call it the microFIT program, and they are offering about a dollar per kWhr.
Chi Meson
Dec15-11, 03:14 PM
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Sorry for not allowing PMs, but it's due to the condition of being a teacher; I got swamped early on with students (not my own) who saw I was a HS teacher and said "this guy will answer my questions without posting in the HW section...

Anyway, I tried to read all the posts heretofore, and I'll recap:

0th priority: location. You pass.

1st priority: roof slope facing south. Even in Sunny CA, an east-west orientation makes roof-mount not effective. But with a little property, a ground-mount can be very useful.

2nd priority: roof tilt. If the first 2 priorities are passed, then any roof tilt will be good. Generally, optimal tilt is your lattitude +10 degrees. But with south-facing roof, or close to it, where you are even a 20 degree tilt will be fine.

3rd priority: thermal panels are cheaper, quicker and most efficient in payback, compared to photovoltaic, no matter how your water is heated currently. If you are in a no freeze zone, it gets even cheaper and you can consider in-line evacuated tubes (even if it freezes a couple of times in your location, its worth it if you can drain-down the tubes before the temperature drops). Heck, you could put a black plastic bag on the roof and get all the hot water you will ever need.

For photovoltaic, if you're going for 2kW, might as well go for 5kW. The inverter is a big chunk of money, up to half of the total price. WIth the inverter, you will get the grid intertie, and you don't need the batteries to store your electricity. Inverters must be sized to the kW of the system, so you can't decide to "add-on" later without getting another inverter; lesson: go large as possible at the start.

I don't know how CA does it, but if you put an 8kW system on your roof, you might be getting paid by the utilities for producing more than you use.
Ivan Seeking
Dec16-11, 11:34 PM
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If you tie to the grid, your system will operate at max potential as a function of load. If you don't tie to the grid, then you have to worry about matching the load to the source, which is a constantly moving target. This is where small dedicated systems can lose a lot of efficiency.

In the end, the ROI should drive your choice. Payback can take decades if not done correctly.

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