Originally posted by rsilvers
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Time lapse photography might have been able to do it. I wonder if an old cellphone running a timelapse app might become an important sales tool.Comment
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Originally posted by J.P.M. View Post
One of those "every situation is different, and most of'm ain't mine" types of situation. Just seems quite unusual overall to the eye attached to an informed brain is all.
So if the logic seems dumb, it is only because the incentives are unusually good (and arguably unfair to non-solar users).Last edited by rsilvers; 05-11-2016, 11:21 AM.Comment
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Originally posted by ButchDeal View PostIn his area the sun will rise just north of due east and set a few degrees north of west.Comment
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yep, but no convincing the customer because he is "in the industry" and knows best.
I told him we would not install on the north over the south and if that is what he wants, he should find another installer.
He stated that he thought he spoke to them all and was going to have to do a self install.
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Originally posted by compchat View PostHad a system installed with two inverters and 42 panels. Some were placed on south roof and some were placed on the North roof. The system is rated 11 KW D.C. with two inverters.
I live in Southern California and currently the 23 Southern roof panels in full sun without clouds generate around 3700 watts during peak hours . It has a 6 KW inverter.
The North Roof is generating about 800 watts with 19 panels (265) under same circumstances.
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Just to close this off and give some prospective owners coming to this thread for some advice about West-facing panels vs North/South/East, I've done some calculations based on PVWatts data and SCE TOU rates and West-facing panels can be nearly as cost-effective as South-facing panels when you take TOU rates into consideration.
For example, an 2.5kW system where I live in SoCal can produce the following:
-- South-facing: 4250kWh and $780 in NEM credits
-- West-facing: 3725kWh and $770 in NEM credits
-- East-facing: 3576kWh and $610 in NEM credits
As you can see, while South-facing panels do indeed produce the most energy and NEM credits, West-facing panels are within 1.5% monetarily, despite the fact that they produce over 12% less energy. East-facing panels, while producing similar amounts of energy to West-facing panels, don't even come close to generating the same amount of NEM credits.
I didn't even bother doing North-facing when I did the calculations as annual production would be abysmal, in addition to receiving no "help" from TOU rate structures.
In my eyes, West-facing panels are just as good as South-facing panels from a financial standpoint. East-facing panels are not nearly as "lucrative," and North-facing panels should never even be considered (I'm obviously talking about the Northern hemisphere and not near the equator).
If you are the type to be concerned about your carbon footprint (due to offsetting the coal power plants during times of the day with of high energy demand), then West-facing panels are a no-brainer. This is a reason why certain municipalities are giving credits to home builders that provision for solar panels on West-facing roofs.
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Originally posted by SolarFuture View PostJust to close this off and give some prospective owners coming to this thread for some advice about West-facing panels vs North/South/East, I've done some calculations based on PVWatts data and SCE TOU rates and West-facing panels can be nearly as cost-effective as South-facing panels when you take TOU rates into consideration.
For example, an 2.5kW system where I live in SoCal can produce the following:
-- South-facing: 4250kWh and $780 in NEM credits
-- West-facing: 3725kWh and $770 in NEM credits
-- East-facing: 3576kWh and $610 in NEM credits
As you can see, while South-facing panels do indeed produce the most energy and NEM credits, West-facing panels are within 1.5% monetarily, despite the fact that they produce over 12% less energy. East-facing panels, while producing similar amounts of energy to West-facing panels, don't even come close to generating the same amount of NEM credits.
I didn't even bother doing North-facing when I did the calculations as annual production would be abysmal, in addition to receiving no "help" from TOU rate structures.
In my eyes, West-facing panels are just as good as South-facing panels from a financial standpoint. East-facing panels are not nearly as "lucrative," and North-facing panels should never even be considered (I'm obviously talking about the Northern hemisphere and not near the equator).
If you are the type to be concerned about your carbon footprint (due to offsetting the coal power plants during times of the day with of high energy demand), then West-facing panels are a no-brainer. This is a reason why certain municipalities are giving credits to home builders that provision for solar panels on West-facing roofs.Comment
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Originally posted by john phillips View PostThere must be a time of use billing. If time of use was not in the equation east and west would be 12% less than south. is that what you are saying?
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Originally posted by jflorey2 View PostThat's one factor. A second factor is that in Southern California, during the best solar months, we tend to get low clouds (June gloom) from morning until noon or so. Thus orienting them southwest rather than west maximizes production during peak months.Comment
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Originally posted by jflorey2 View PostFor May and June definitely. Usually it ends in July/August, but this has been a strange year.Comment
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Originally posted by SunEagle View Post
Damn weather is going to make a lot of the estimations from pvwatts wrong. Hope it clears up for you guys.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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The weather is what it is, and it's not climate. Climate's what you expect. Weather is what you get. Solar models use what's probably best described as climate modeling.
As Sensij notes, and as PVWatts info screens discuss, that, or any other model cannot estimate any short period's solar production any more accurately than a weather forecast. I would suggest however that while PVWatts states that monthly results from the model can vary by up to +/- 30 % vs. for an actual month, yearly values can also vary by as much as +/- 10%.
I've got a clear sky climate model that estimates my array will produce about 11,140 kWh/yr. using Miramar TMY3 temp. & wind data and the HDKR model for clear sky irradiance. The same model, using TMY3 Miramar data including irradiance comes up with 9506 kWh/yr., or 85.4% of a clear sky.
My array has been live since solar noon, 10/17/2013. zip 92026, about 20 airline miles from the coast. I keep a running total on the 365 days of prior array production since 10/18/2014. The lowest prior 365 day running total is 9,033 kWh/365 days. The highest prior 365 day running total is 9,644 kWh/365 days. Average, 9,298 kWh/prior 365 days. Std. dev. for prior 365 day running total is 187.3.
So far the array has produced 24,628 kWh. the theoretical clear sky production might be about 30,170 kWh. 24628/30170 = 81.6%, or about 3.8% shy of model est. I've not got the #'s handy for actual clearness index at my location vs. the clearness index for the TMY3 data, as it's not been a priority, but I'm working on it.
BTW, I believe there's a lot of desert in SO. CA that doesn't see a lot of morning/coastal fog or May/June cloudiness. To say or imply all of SO. CA climate is described by what happens relatively near the coast may not be entirely accurate. My location is ~ 1,400 ft. above sea level and while I get some morning fog, it almost always burns off by 0800 or so. I watch the fog retreat to the coast as I do my morning rants. Just sayin.
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