The Summer Solstice was at 1:45 a.m. EDT on June 21, 2009. It was kind of cloudy here all day Sunday ... just like the prior 2 weeks. But TODAY? Monday !?!?! ... all day sun! Adding the results of the 2 inverters (each capable of doing 4Kwh) together we got (drum roll) FIFTY & 3/4 Kwh today! Woo hoo! Not the longest day, but darn close. Since we've been up & running now for about 1/2 a year, we can do calc's for the rest of the year. That 50Kwh number sounds impressive to me, but with roughly 14 hours of daylight at our So Cal Lattitude, that's actually less than 4Kwh per hour. Once you factor in Winter months with roughly 9hrs of light ... and the sun not going anywhere NEAR as high in the sky ... well it makes me wonder. Our panels are rated at 225 watts each. Times 36 panels and you have a HUGE number. But in reality, with panel angles never being perfectly aligned during the day (except for maybe a couple minutes) ... that "advertising number" gets bumped down quite a bit. Not that we're crying ... what with a 190Kwh surplus. It's just funny how the numbers go.
Nice! I think the best we've done has been approximately 31 kWh. I didn't think to check it yesterday, but it was likely in the high 28's or low 29's, which is about as good as we get.
My best day ever was about 15kWh. We have a 3.3 kW system. However, it's been overcast here for like a whole month and we're been lucky to get anything over 11kWh per day this summer. Honestly though, I don't mind marine layer over free electricity in the summer time.
Same here ... I don't mind the marine layer / clouds. It beats running the AC. What I do mind though is the way the PV industry rates by a "high" number. I'd be nice if they based production of the reality of panel inclination, short seasons, early morning & mid day production, etc.
Hmmmmm, When we had our system put in, our salesman did tell us what the approximate max output would be (~ 4 kW/hour) and an estimate of what our yearly production would be (~ 6600 kWh). The only bit he left out was that the panels will produce more electricity if they are cooler (assuming the same amount, intensity of light). A fellow at work pointed it out (sans physics equations) to me as he has panels too. I think Hill can run a 150 gallon reef aquarium and still have a surplus of electricity (I've got PV envy).
I duno ... admittedly the 190Kwh sounds like a big reserve. But divide the reserve by the days in a half year? It's less than 1Kwh per day, right? We get an EV, and we'll have to switch to a TOU meter.
Cody, Pv panels will produce more power in direct proportion to a drop in PV temperature. (I've got a formula but I don't have it handy) In my case,, my small off grid system will,, in the height of winter with reflection off of snow and temps near -40 my system will nearly double it's summer highs. Northern climes will yield better than desert SW locals,,, but the reality is that PV panels absorb heat quite quickly so that much of the advantage is lost as the day heats the panels,,, unless it is very cold. There have been several schemes to try to cool panels,, including building one that uses cooling water to heat Domestic hot water. None have proved to be cost effective, that I know of. I get my best harvest near the Spring equinox,, I get fairly long solar exposure on my panels,, we are still quite cold,, -25 over night,, maybe near freezing during the day with lots of reflection. On the other hand,, I use almost no power at the height of summer,, since it is light at 4 AM and stays light enough to read at 10:30 PM so my lighting load is near zero! Icarus
Have PV systems come down in cost at all over the last few years? I'm interested, but the initial investment is still pretty steep.
Right now is a great time to buy Pv hardware. Panel costs have never been lower. I can by name brand Pv panels for as low as ~$2.30/ watt. Couple that with tax incentives, utility rebates etc,, the pay off gets way better,, depending on your location. Having said that,, remember, even now,, investing in Pv solar only makes sense AFTER you have done everything to conserve. As we suggest in the Solar business,, every dollar spent on Pv will save ~$10 in Pv costs. Good luck, Icarus
I have yet to hear any salesman or PV company tell me I would get the rated number. The rated watts per panel is simply that, a concrete number that the panels are capable of. It can be easily measured and quanitified. The salesman SHOULD make it clear that this is the possibility under 'perfect' conditions. That being said, May is probably going to be out high output this year as it was very sunny, while June was extremely cloudy (we actually just beat February with our June numbers). The shorter days in winter are not too much of the hit for non-tracking panels as generally you get the bulk of your power between 10am and 3pm. As mentioned above, the efficiency of the PV panels goes up as the temp goes down, which generally makes up for that. However, for many people, winter is much cloudier and that will kill your power production.
Panels get cheeper, like cars, as the next model (efficiency) comes out. So when 18% efficiency panels came out, the cost of 16% - 15% - 12% effficiency panels began to drop. .
