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| South & West facing on one string http://solar-guppy.com/forum/viewtopic.php?f=3&t=540 |
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| Author: | BB [ Mon Apr 30, 2007 1:28 pm GMT EthGMT ] |
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T, Don't install it unless it make sense (lots of good sun from ~9am-3pm at least). Mine works fine (near SF CA, behind a coastal mountain range that protects against much of the ocean fog). Even with the ~$2.50 a watt CA rebates and Fed Tax credits (I got about 1/3 back), it still costs me more than my current electric rate (guess around ~$0.17 per kWhr over 25 years assuming I have to replace the inverter at least once in that time vs $0.11 per kWhr for baseline electricity). A 3.0 kW system (20 BP 4175 175 watt panels, Xantrex GT 3.0, E7 Time of Use metering, 1 year net meter billing) generates more power than my family of four currently uses (panels generate about 4,800 kWhrs per year). Enough left over to help with an Electric Car sometime in the future. But, I only did this once I went through and completely gutted/remodeled for energy efficiency (double pane vinyl windows, energy star appliances, new forced air furnace, wall insulation, etc.) my 65+ year old home. If you have not done about 95% of what is needed to improve efficiency, or you have shadows from gables and/or power lines and trees (remember that trees on other's property will grow over 20-40 years)--solar electric may not be a good fit at this time. Another option to consider is solar hot water... The panels take up about 1/4 the roof space (for the same "energy") and are not near as sensitive to partial shading during the day. If you are relatively efficient on your electrical use--you could save about as much money on your gas bill as you would have saved on your electric bill. Also, again in terms of "energy", solar hot water panels cost about $0.50 per watt vs the $5.00 a watt for solar electric. The down sides for solar hot water include; needing to install ~20+ gallons of water storage tanks per resident, installing pipes/pumps, and issue of life with the hot water panels/tanks/plumbing/pumps/anti-freeze or no anti-freeze. Maintenance will also be more $$$ with solar hot water vs Grid Tied solar electric. I know that Solar Guppy is a solar electric kind of guy... But, perhaps, he has some words of wisdom regarding good manufacturers of solar hot water panels. I personally am still thinking of adding solar hot water to my home--But for several issues. First is my "good roof space" is already covered by solar PV panels; second around my area there are some solar hot water systems (all appeared to have been installed decade or more ago) and I would be hard pressed to believe that any of them are still working because of solar panels that are falling apart, broken tracking systems, etc. The few that are newer seem to be for swimming pools where plastic plumbing and low temperature (& cheap plastic open faced) panels are an accepted way of life. -Bill |
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| Author: | tsshfs2005 [ Mon Apr 30, 2007 2:34 pm GMT EthGMT ] |
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Hi Bill, thanks for your insight. Yes, my south & west roof should get at least 6 good hours of sunlight. We do have double windows, energy star appliances, but do need to insulate our attic more. We did consider solar hot water, but it did not seem cost effective since our monthly hot water is down around $15. Now if I could get my gas heating bill down, that would be good! Solar Guppy, Thanks for the tip about the smaller panels. I was thinking that might make it easier for the installer to work around my vent pipes. I pretty much told him if he can get 2 balanced strings of Sharps on my roof, I'd sign a contract. Seems like you & other folks are also monitoring the Arizona Wind-Sun forum, so I'll continue additional queries there. Thanks. Tom |
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| Author: | tsshfs2005 [ Mon Apr 30, 2007 2:44 pm GMT EthGMT ] |
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Solar-Guppy, I just read your suggestions about the KCs and Photowatts (somehow I missed that post earlier). I'll mention that to my installer also. I may have constrained him too much by wanting black frames for the front for aesthetic reasons (I really wanted him to put in the new Sharp 142/72 with the triangle panel) but I think I'll have to back off that requirement. Thanks again. Tom |
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