Local energy provider (SMUD) forced me to reduce my planned production

[inetdog]

Sorry, I misread the original post. (Which interchanged kW and kWh, by the way.)

[J.P.M.]

I actually talked to the approval engineer which was nice. She said the caps are California law, and not even their decisions based on actual usage. I think I will be good with 6,160 kwh (22x280) for the long term. She mentioned that she wouldn't be able to off-set shade loss even or make exceptions for future plans. Her two suggestions were to wait until my use equals my desire, or to expand later. The expansion though would be a much simpler project for them, but would still require permits and such.

She crunched the numbers though and tried her best, which I appreciated. I really only have one roof section that is suitable for solar which is why I just wanted to maximize all at one time and be done with the whole project. See attached for the drawing. They removed two of the top four at first and rotated the remaining two 90 degrees. Now with only three going back I guess they will just center them.

As for caps, there may be POCO mandates/caps allowed by CA law or CPUC regs., but since SDG & E allows system sizes up to 1MW and there are several > 10 kW arrays that are less than 1 yr. old in my HOA. I do not think 10 kW is a size limit set by the statute or the CPUC.

Rooting around on the SMUD website in a somewhat cursory way, and unless something has changed since what I was reading was written (copyright 2016), it looks to me that SMUD will not pay their $500 system incentive on systems that are excess generators, however that's determined, but that's still not an absolute dictate on system size, just incentive payments.

The confusion between kiloWatts and kiloWatt-hours seems to be creeping back into the text. See OP post of 09/30, 3:39 P.M.

[foo1bar]

How am I missing that???

We're talking about a 6.44kW system vs a 5.88 (or 6.16)kW system.

The 10kW max system size doesn't really matter for these - none of the options he's looking at are that big.

[inetdog]

So if I read right, your actual usage for the past 12 months is 10,095 kwh (that's what I'm reading
And your planned install will produce 10,082kwh
So isn't your actual usage already larger than your planned install?

What you are missing is that PG&E and SMUD both follow the California Net Metering law which, AFAIK, only requires POCOs to offer Net Metering on nominal system sizes up to 10kW.
It does not matter if the panels are flat at a bad angle, severely shaded, or on two axis trackers for entirely different kWh production, the system size limit is 10kW.

A POCO could voluntarily accept a larger system IF their tariffs allowed that, but no business person would likely make that choice.

[sunnyguy]

Well at least it uses last 12 months, but sadly that doesn't cover your upcoming winter hot tub usage.

10095 * 100% offset \ 1.65kwh/w = 6118w / 280w/panel = 21.85 panels

[easye]

with that SE7600 you could add at least 3 more panels probably 4. I added panels to my SE system with no issue. Heck, ground mount them if you want to. the extra length is easy to find on amazon and the connectors make it stupid proof. Just make sure it's grounded!

[foo1bar]

I actually talked to the approval engineer which was nice. She said the caps are California law, and not even their decisions based on actual usage.

So if I read right, your actual usage for the past 12 months is 10,095 kwh (that's what I'm reading
And your planned install will produce 10,082kwh
So isn't your actual usage already larger than your planned install?
PG&E has a thing which says NEM installs should be less tan 110% of prev. 12 months and projected future increase (emphasis mine)
So I don't think PG&E would do something that's against CA law.

She crunched the numbers though and tried her best, which I appreciated. I really only have one roof section that is suitable for solar which is why I just wanted to maximize all at one time and be done with the whole project. See attached for the drawing. They removed two of the top four at first and rotated the remaining two 90 degrees. Now with only three going back I guess they will just center them.

Are you going to be on TOU plan?
If so, you may be better off with less kwh because on a $ basis your bill will still be $0. (80% or 90% on a kwh basis will probably still get you a $0 bill)
If not, and if you can't get a change from SMUD you'll need to talk to your installer.

I'd ask them to build everything as if it was before - and to just leave the one panel out of the electrical circuit.
I think that you can later on increase the system size by 10% from it's original size without having to redo the POCO paperwork.
You can check on that with the POCO - "I expect I'll need a bigger system in a year - is there anything I need to get approval for? or paperwork I need to file to increase the size by 10%?"
Then in 12 months you can get a building permit and increase your system size by 1 panel by hooking up the panel.

BTW it looks like you're using 280W panels.
That should be a good price - but if you really want to maximize your roof and are definitely going to need more production later, it may be possible to change to 300W panels for an additional cost. Then reduce the number of panels (ex. take out the top row) and if you need to increase later on, you'll have room for more panels.


If you are on TOU SMUD is probably helping you by keeping you from spending money unnecessarily.
If they aren't on TOU, and they won't let you go with a 10,082kwh system, and you can increase capacity by 10% without POCO approval I'd make it easy to add that 10% capacity.
I believe that it's legal to have non-electrically connected modules on your roof for aesthetic purposes.

[steveholtam]

I actually talked to the approval engineer which was nice. She said the caps are California law, and not even their decisions based on actual usage. I think I will be good with 6,160 kwh (22x280) for the long term. She mentioned that she wouldn't be able to off-set shade loss even or make exceptions for future plans. Her two suggestions were to wait until my use equals my desire, or to expand later. The expansion though would be a much simpler project for them, but would still require permits and such.

She crunched the numbers though and tried her best, which I appreciated. I really only have one roof section that is suitable for solar which is why I just wanted to maximize all at one time and be done with the whole project. See attached for the drawing. They removed two of the top four at first and rotated the remaining two 90 degrees. Now with only three going back I guess they will just center them.

[foo1bar]

Neither. Unless the inverter has dual input capability with independent MPPT, the string voltages need to match one another. Check your inverter spec sheet.

Steve - I think you just said you're using Solaredge SE7600.
If so, the strings will take care of themselves. There's no reason the company couldn't have just removed one module. The strings for a solaredge system can be significantly mismatched between the 2 strings (although there are minimums and maximums)
Possibly the installer dropped two modules for aesthetic reasons.

Did SMUD say what the max size system that they can allow (based on kwh or on kw)?
First, I'd look at whether you really need/want the larger system. (SMUD may be helping you by keeping you from installing too big of a system)

If you really need/want the larger system I'd ask them if they'll reconsider, since
1> your electric usage has gone up by ____ kwh/month from last year because of new hot tub and new EV. So your projected usage for 2017 is ____ kwh.
2> you have shading and the system needs to be bigger to compensate for the shading.

[J.P.M.]

Would an odd number of panels make this worse or better? Or is just the math per string?

Neither. Unless the inverter has dual input capability with independent MPPT, the string voltages need to match one another. Check your inverter spec sheet.

[steveholtam]

Would an odd number of panels make this worse or better? Or is just the math per string?

[Wy_White_Wolf]

If the 2 strings were paralleled they would have to remove/add one to each string to keep the voltages the same.

WWW

[steveholtam]

Thanks for the replies. I called SMUD and they said they only requested one panel be removed, not two. Not sure why my solar company removed two. Either way, I sent them a message to add one more panel back, getting closer to my original plan. And I will be keeping the original inverter (SolarEdge SE7600) so that I will still be able to add panels later if need be.

[jflorey2]

How come they are able to dictate my private purchase?

Because you are feeding back into a public utility. If you generated all your own power this would not be an issue.

And can I add panels down the rode if I get their blessing?

Depends on your system. You can often add panels to a series string as long as you do not exceed the max voltage (which must be calculated at the lowest expected temperature.)

[cebury]

Yeah each utility can dictate certain terms for system size. PGE is fairly generous in that their allowance and allow for new purchases like hot tub or EV -- right on their interconnect application itself. Guess SMUD doesn't, but I'd get a second opinion from them.

Once you add on the fees for upgrading your system, it can really push out payback quite far for an additional few panels. I'd count my blessings at this point...