Valdemar
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Re: Official Southern California Edison thread

Fri Oct 14, 2016 7:44 pm

smkettner wrote:Aim to cover 50% of your usage with solar for maximum return on investment.


One size doesn't fit all. Also rates and rules change all the time all the time and this may not be a good advice long term. It may end to be beneficial to lock into a NEM agreement with a system that covers more than 50%.
'11 SL, totaled
-1CB@33k/21mo, -2CB@53k/33mo, -3CB@68k/41mo, -4CB(41.5AHr)@79k/49mo, -5CB(38.85AHr)@87.5k/54mo
-0CB(66.14AHr)@87.5k/54mo (BBB)
59.7AHr, SOH 93%, 118k miles
9kW Solar

SurfHawk
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Re: Official Southern California Edison thread

Sat Oct 15, 2016 5:24 pm

Thanks for the replies, this info is helping me wrap my head around this TOU stuff.

Valdemar wrote:Baseline credit w/o solar is simple, you get 10c credit per kWh up to your monthly baseline allocation, check with SCE what that number is for your area. It gets slightly more complicated with solar, as you may end up paying this money to SCE if you system generates more than you consume per pay period.


We are in Zone 6 which gives us 9.4kWh per day in summer, works out 286kWh per month. Does that mean we get a $28.60 credit if we go on TOU-D-A in the summer? That would be great.

First solar guy said to get a 3kW system if we didn't get a EV, 4kW if we did. We then bought the Leaf and had the second solar guy out, after I had some usage with the Leaf. He has yet to quote but sounded like he wanted to go smaller than guy #1. Second solar guy is a Nissan Leaf owner on a TOU plan, so his suggestions could be good.

Thanks for all the help.
2013 Leaf S w QC - Purchased 10/2016
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smkettner
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Re: Official Southern California Edison thread

Sat Oct 15, 2016 5:41 pm

My SCE bill shows a separate line for 320 kWh and a 31.61 credit independent of all other charges.
746 kWh was net usage.
1 bar lost at 21,451 miles, 16 months.
2 bar lost at 35,339 miles, 25 months.
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tbleakne
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Re: Official Southern California Edison thread

Wed Dec 28, 2016 9:51 pm

Those of us in SCE territory can be relatively grateful we live in one of the better utility territories for Solar Net Metering, despite the recent changes. However, we need to be vigilant because this push-back from the utilities is relentless.

Dec 21, 2015: Arizona Vote Puts End to Net Metering for Solar Customers

https://www.greentechmedia.com/articles/read/Arizona-Vote-Puts-an-End-to-Net-Metering-for-Solar-Customers

compensate distributed solar exports based on a five-year average of utility-scale solar PPA pricing.

Recent Utility-scale prices are really low, because economies of scale bring the installation price down to about $1.20/watt or even lower, which is about 1/3 the price charged for residential roof-top installations. I feel distributed solar is worth much more, closer to retail, because our power is consumed locally without using the HV grid, but utilities don't want to see it that way.
compensation for distributed solar exports using the RCP methodology would remain around 11 cents per kilowatt-hour for most customers, which is nearly on par with the current retail-rate net metering credit. However, updated assessments that include the latest utility-solar pricing could put the actual RCP credit rate significantly lower.

regulators approved keeping current distributed solar customers on their current rate plans for up to 20 years from their interconnection date.


A ruling in Louisiana Nov 2016 looks worse:

http://www.katc.com/story/33764612/louisiana-public-service-commission-eliminates-cap-on-solar-net-metering

any residential or business customer will be credited for every kilowatt hour (kWh) of electricity they put onto the grid for an equal amount of energy in return during the monthly billing period. Any credits in excess of their use during the month will roll over to the following month, but now at a lower "avoided cost" wholesale rate.


"Avoided Cost" can be really low, below wholesale, if the utility just counts the fuel saved by your generation, since wholesale also includes capital cost of both generation and transmission.
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
Sold June 2014 27K miles, 18% capacity loss, 1 bar, 5.0 mi/kWh.
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tbleakne
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Re: Official Southern California Edison thread

Mon Jan 30, 2017 2:16 pm

My January 2017 SCE NEM statement included a Billing Adjustment of $-76.00 for period January 2016 to January 2017. I confirmed by phone that this adjustment is the CA Energy rebate that was issued in two parts previous years in Oct and April. The lady told me this is real money, not just energy charge credit, and they have a check in the mail for this amount less $9.31 the monthly charge in real money.

I have the option of applying this credit toward the monthly payments of real money (local taxes + minimum charge) instead of cashing the check.

This is my 12th month of my relevant period. By running my heat pump like crazy in this cold weather, rain days with no solar production, and extra driving, I was able to eat up $144 of my -$290 cumulative credit, leaving -$146. which I believe will be erased next month.

With my new solar array doing well in beautiful clear weather today, and no heat pump need, I reached a peak power going back into the grid of -5.1kW. In May I should do even better.
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
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Valdemar
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Re: Official Southern California Edison thread

Mon Jan 30, 2017 2:25 pm

February-May are the best months for credits, usually lots of sun in SoCal, clear air, cooler temps, no AC and the panels are still clean(er) after the rains.
'11 SL, totaled
-1CB@33k/21mo, -2CB@53k/33mo, -3CB@68k/41mo, -4CB(41.5AHr)@79k/49mo, -5CB(38.85AHr)@87.5k/54mo
-0CB(66.14AHr)@87.5k/54mo (BBB)
59.7AHr, SOH 93%, 118k miles
9kW Solar

tbleakne
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Re: Official Southern California Edison thread

Sat Mar 25, 2017 12:51 pm

Valdemar wrote:February-May are the best months for credits, usually lots of sun in SoCal, clear air, cooler temps, no AC and the panels are still clean(er) after the rains.

Yes I agree completely. We have had some really cool (for us) clear days in February and March. Cool temperatures can easily increase output 10%. The weather in the fall is not as favorable, so production is less even though the sun angle is the same. September is much hotter than March.

I just woke up to the fact that SCE is now stating on their web page that ALL residential customers will be transitioned to TOU in 2018, per a CPUC order from 2015. Being grandfathered under NM 1.0 does not protect you from being moved to TOU.

Net Metering 2.0 begins July 1 of this year for SCE customers, and so they will find themselves on TOU this summer.

https://www.sce.com/wps/portal/home/residential/rates/Time-Of-Use-Residential-Rate-Plans/Residential-Rate-Changes/!ut/p/b0/04_Sj9CPykssy0xPLMnMz0vMAfGjzOK9PF0cDd1NjDz9g_3MDRwNg1193QN9jF3NTPQLsh0VAWjlRv8!/

I have found it fairly difficult to explain to friends how TOU can be your friend, particularly if you have solar and/or charge a car. I urge folks on this thread to help spread the word.

Of course SCE is free to keep playing with the TOU schedule. At some point as solar penetration increases, I would expect them to move the start of On-Peak from 2pm weekdays to 4pm weekdays, for example. However, I do quite well making my main profit Off-peak.
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
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abasile
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Re: Official Southern California Edison thread

Sun Mar 26, 2017 8:53 am

tbleakne wrote:Cool temperatures can easily increase output 10%.

Wow, that is quite significant! We just installed a SunPower system on our roof (with 360W panels to maximize production per unit area) and SunPower claims that their efficiency loss at higher temperatures is more modest than "typical" panels. If this is the case, I wonder whether we'll see much benefit from our lower temperatures up here in the mountains.

tbleakne wrote:I just woke up to the fact that SCE is now stating on their web page that ALL residential customers will be transitioned to TOU in 2018, per a CPUC order from 2015. Being grandfathered under NM 1.0 does not protect you from being moved to TOU.

It seems to me that this could have the effect of motivating more customers to install solar for the first time, to take the bite out of peak usage charges.

In our case, whether "peak" is from 2 PM - 8 PM versus 4 PM - 9 PM probably isn't much of a concern. Either way, our production during peak hours appears to be pretty low due to shading. We installed a relatively large system, 6.48 kW DC, to compensate for the fact that we may be losing roughly 40% of our theoretically possible production to shade, primarily in the afternoon hours. In March, our best production is from roughly 9:30 AM to 1:30 PM (PDT). Obviously this means that it will take significantly longer for the system to pay for itself (I'm guessing 10-12 years), but we'll still come out ahead in the long run, and have the satisfaction of producing clean energy.

For us, it also helps that we don't use air conditioning, thus keeping our daytime usage from getting too high. That said, there are some days when we wish we had A/C. I'm speculating that with panels on the roof, our solar heat gain may be mitigated somewhat.

Finally, I have a comment about PV production, shading, and clouds that's probably obvious to PV veterans. During the hours when the majority of our panels are in shade, I've noticed that clouds or haze in the sky can help by diffusing sunlight, thus enabling more solar radiation to reach the shaded panels. Our best overall production has occurred on days that are mostly sunny but with significant high clouds. Totally clear and crisp days aren't quite as good for production, by a factor of about 10% less.
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tbleakne
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Re: Official Southern California Edison thread

Tue Mar 28, 2017 11:59 am

Congratulations, abasile, on your new solar installation. 6.48 kW DC is a lot of power for your relatively small roof. Going with Sunpower with its very high efficiency looks smart.

Your panels are excellent; don't worry

1. The power temperature coefficient of your 360W Sunpower panels appears to be -.30%/C vs -.38%/C for both my new LG Neon-2 panels and other Sunpower panels. Your maximum efficiency is 22% vs mine of almost 19%. 22%/19% = 16% more output per area. Your panels probably will not get nearly as hot as mine on most days, with partial shade and cooler mountain air. The negative temp coefficient means all panels decline in efficiency vs their STC ratings at elevated temperatures, so yours will decline a little less.

So would your panels underperform in clear cold mountain weather? (22-19 %)/(.38-.30 %/C) = delta 37 C, 67.5F. STC is 25 C, so the temperature would have to fall to 25 - 37 = -12 C before your panel efficiency would drop down to LG panels.

2. Yes, if air can circulate underneath your roof panels, your roof will be cooler. I am expecting this benefit as well for my new installation, which sits over my attic and my office and bedroom. You might also consider a small mini-split system if you decide to add active cooling powered by your solar production.

3. Higher production during partial clouds: this is a little surprising. In clear weather the trees shading your roof will cast strong shadows with moving patterns of shade and full illumination. Partial clouds can reduce the contrast between illumination and shade.

Most panels are organized into 3 subpanels each with one bypass diode. Dark shade blocking any one of the 20 cells in one subpanel will shutdown all output of the other cells in series in that subpanel. Modern string inverters are good at adjusting the string voltage such that a single cell will shutdown only one subpanel.

I believe your Sunpower panels have an integrated micro inverter in each panel, with 3 subpanels in series. It is possible that the micro inverters do not operate well if 2 of the 3 subpanels have shade because the panel voltage is too low.
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
Sold June 2014 27K miles, 18% capacity loss, 1 bar, 5.0 mi/kWh.
Solar 4.6 KW DC with both string and micro-inverters.

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abasile
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Re: Official Southern California Edison thread

Thu Mar 30, 2017 9:25 am

tbleakne wrote:(1) So would your panels underperform in clear cold mountain weather? (22-19 %)/(.38-.30 %/C) = delta 37 C, 67.5F. STC is 25 C, so the temperature would have to fall to 25 - 37 = -12 C before your panel efficiency would drop down to LG panels.

Actually, the resources I've found seem to indicate that PV efficiency continues to improve as the temperature drops below STC. For example: http://www.sciencedirect.com/science/ar ... 7913000403

In that article, there is a graph that shows significantly greater power at 0 C compared to 25 C. Other resources suggest the same thing. Reportedly, PV panels in Antarctica have done quite well in terms of efficiency, when the sun is visible that is.

However, as our panels have a smaller power temperature coefficient (-.30%/C) than yours, I'd expect that their efficiency advantage at low temperatures may not be as great. That said, particularly as panels can become much warmer than the ambient air temperature, I admit that this should be only a relatively trivial concern for us - the smaller coefficient should do us more good than harm.

tbleakne wrote:2. Yes, if air can circulate underneath your roof panels, your roof will be cooler. I am expecting this benefit as well for my new installation, which sits over my attic and my office and bedroom. You might also consider a small mini-split system if you decide to add active cooling powered by your solar production.

Yes, there is some room for air to circulate under our panels, and on warmer days with intense sunlight, I think we are already noticing a cooling effect upstairs.

Thanks for the tip to consider a mini-split system, something I hadn't previously investigated. As these systems utilize heat pumps and can perform both heating and cooling, this might fit into my longer term goal of reducing and ultimately eliminating the use of natural gas for home heating (and cooking).

tbleakne wrote:3. Higher production during partial clouds: this is a little surprising. In clear weather the trees shading your roof will cast strong shadows with moving patterns of shade and full illumination. Partial clouds can reduce the contrast between illumination and shade.

Most panels are organized into 3 subpanels each with one bypass diode. Dark shade blocking any one of the 20 cells in one subpanel will shutdown all output of the other cells in series in that subpanel. Modern string inverters are good at adjusting the string voltage such that a single cell will shutdown only one subpanel.

I believe your Sunpower panels have an integrated micro inverter in each panel, with 3 subpanels in series. It is possible that the micro inverters do not operate well if 2 of the 3 subpanels have shade because the panel voltage is too low.

With respect to clouds, the best scenario occurs when the sun is not blocked at all and clouds elsewhere in sky reflect the sun's light onto our roof. But even a completely overcast afternoon (starting at 2:30 PDT or so when the roof is mostly shaded) seems to beat a sunny afternoon in terms of our production.

Yes, our panels do have integrated micro-inverters. I may at some point try taking photos of our panels in partial shade and comparing with our panel-level power production, to help me better understand what's going on.

Finally, something else to note is that, according to our installer (LA Solar Group), we may be able to install additional panels by utilizing our north-facing roof and employing a "reverse tilt" to the south. For a single row of panels not too far below the ridge (we'd need a three-foot offset below the ridge for code compliance), it seems to me that this could work well. Our roof is scarcely visible from the street, so aesthetics aren't too big a concern up there. Depending how things go, this could be an option to consider next year.
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