Questions on 25kW Residential Cap in NY

[phantasms]

I posted several months ago about trying to get thoughts on a solar setup on my roof. Issue is the place is a castle and the roof is crazy. Everyone said looks like a nice roof for a ground array. lol Now I'm looking at that. One of the many installers who contacted me told me I can only do up to a 25kW system. With some searching I see "limited to the maximum system size cap of 25 kW DC for residential installations ". I'm not sure if this is just a NY thing but what's the deal? We don't even have electric cars yet and use more energy than a 25kW system will deliver. We have plenty of sunlit lawn just asking for panels. Is there any way around this? Should I simply setup a 25kW system, get the incentives, inspection, etc etc etc and then a few months after everything is said and done simply add more panels to the system? lol As I have a building company I'm planning on doing the install myself anyway. I'm figuring a single axis long ground array mount. My calculations put me at needing, once cars are involved, a 45kW system. Thoughts?

Thank you!

Best,
Gene

[sensij]

Are you sure your calculations are correct? That is a ridiculous amount of power for one residence. Electric heat?

My electric car consumes less than 4000 kWh annually, for about 15k mi. That takes less than 2.5 kW of PV to supply here. How many cars do you drive to require 20 kW?

[SunEagle]

You may consider yourself lucky. Some POCO's limit the amount a residential property can co-gen to 10kw and others will not allow any grid tie system at all.

Each state and POCO have their own rules and limitations. It looks like NY may be more lenient with that limit.

[J.P.M.]

Are you sure your calculations are correct? That is a ridiculous amount of power for one residence. Electric heat?

My electric car consumes less than 4000 kWh annually, for about 15k mi. That takes less than 2.5 kW of PV to supply here. How many cars do you drive to require 20 kW?

Castles have a larger energy budget than the more modest domiciles of the great unwashed masses.

OP: I'd check, but it sounds like your after install/approval plans to increase the array size may run counter to intent of the rules. I'm sure you know eventually you'll be busted.

[phantasms]

Sensij,

Just two electric cars. The residence is large and doesn't exactly have the best insulation despite our best attempts during the renovation. All the solar installers I spoke with asked to see our use history and were surprised by how much we used.

SunEagle,

i <3 NY....and if I ever move...I <3 Colorado. lol

JPM,

Sad but true on the energy usage. Not sure how we would ever be busted. What do you charge someone with? Excessive tree hugging? Consider me guilty! lol

Best,
Gene

[SunEagle]

Sensij,

Just two electric cars. The residence is large and doesn't exactly have the best insulation despite our best attempts during the renovation. All the solar installers I spoke with asked to see our use history and were surprised by how much we used.

SunEagle,

i <3 NY....and if I ever move...I <3 Colorado. lol

JPM,

Sad but true on the energy usage. Not sure how we would ever be busted. What do you charge someone with? Excessive tree hugging? Consider me guilty! lol

Best,
Gene

Hopefully the POCO will not be too unkind if you choose to exceed any power generation limit. Although in some cases if you break a Contract with the POCO they can hit you with just about any type of financial or criminal penalty that is listed in the Contract.

Heck in the County I plan to move to there is some very specific language about not following the permitting process for just about anything. The penalty can go up to $10k and worse you can be charged with a misdemeanor which could mean imprisonment for up to 1 year.

So I would not underestimate what penalties the POCO can hit you with if they are listed in any contract paperwork.

[jflorey2]

Is there any way around this?

Some thoughts that come to mind:
Trackers are expensive, but will allow more energy output with a fixed 25kw of panels.

If the limit will be the AC output rather than the array size, then you could consider a variation on a net zero system - a net 25kw system. Design the system so it will back off and never deliver more than 25kw to the grid. If you overpanel you will then be able to deliver 25kw for longer, and thus get more energy credit overall. If you make sure you run a lot of your loads during the day you can divert 10kw to the loads and still return 25kw to the grid with a 35kw (STC DC array size) system. This will also be expensive and likely take a lot of work; I have never seen one of these systems operational.

Batteries are _hideously_ expensive, but again if you are output limited, they will allow a peak system output of 25kw over a longer period of time - and more self-use of energy.

Keep in mind that if you have a tiered power plan, getting rid of even 50% of your usage may cut your bill by far more than 50%.

[bcroe]

I see "limited to the maximum system size cap of 25 kW DC for residential installations ".
We have plenty of sunlit lawn just asking for panels. Is there any way around this? Gene

There ARE some things possible. With space for unshaded ground mounted panels, you have some options.

Here with a "6 sun hour day", my 15KW of inverters might be expected to collect 90 KWH. But with a long
day and no clouds tomorrow, I'm hoping to collect 150 KWH, a 10 sun hour day. This is done using multiple
strings, some facing the rising sun, some south, some facing the setting sun. These strings are tied in
parallel to the same inverters, delivering maximum power at different times of day. So the peak isn't
increased, but the length of the effective day is. This doesn't work with micro inverters, and anyway
they have too much long connecting line loss at 240VAC.

With lots of space, you can economically build a 2 sided E-W array, in the middle of the clearing. My clear
space is less that an acre, so its becoming sort of a bowl; panels on 3 sides facing across the clearing for
minimum shade.

Don't forget, at day extremes the sun might be coming from north of the panels. So don't back them right
up to some trees, like I did. Now I'm moving them. If you do have the E, S, and W oriented panels, the S
panels may be tilted more vertical catch more of those hours.

For cloudy days, the same setup will boost output pretty much in proportion to
the extra panels; dispersed light from clouds doesn't care so much about orientation. This method
is cheaper and more reliable than tracking, and turns in a lot more energy under clouds.

A possibility is to look for heavy loads that coincide with maximum sun. There are air conditioners
equipped to use PV panels, to reduce AC line load. Water heating might be a possibility. If such things
can be matched up, they won't fall under the PoCo limit. Might take some serious engineering.

I don't see trying to limit power fed to the line to the PoCo limit, as a practical way
to allow a larger PV AC inverter plant. Forget batteries. Bruce Roe
NSnview.jpg

[sensij]

If the limit will be the AC output rather than the array size, then you could consider a variation on a net zero system - a net 25kw system. Design the system so it will back off and never deliver more than 25kw to the grid. If you overpanel you will then be able to deliver 25kw for longer, and thus get more energy credit overall. If you make sure you run a lot of your loads during the day you can divert 10kw to the loads and still return 25kw to the grid with a 35kw (STC DC array size) system. This will also be expensive and likely take a lot of work; I have never seen one of these systems operational.

Looks like NY State law sets the 25 kW limit for net metering, and the standard permitting guidelines are based on DC size, which pretty much kills all the more creative approaches discussed here. It may be worth verifying with the specific AHJ and Poco, but it doesn't look good.

If the OP is willing to forgo net metering, a larger system could be installed, but it is hard to see how that would be cost effective.

[SunEagle]

Best way to save on electric costs is to find ways to reduce electric usage. To me that would finding ways to insulate or reduce my heating and cooling costs which are big contributors to an electric bill.

Of course if you want an EV then hopefully what you save on gas will cover the increased electric for charging.

It is just a matter of what is important to the person when it comes to electricity usage and how much you want to pay for it or for the equipment (like pv) to help you save.

[J.P.M.]

Sensij,



JPM,

Sad but true on the energy usage. Not sure how we would ever be busted. What do you charge someone with? Excessive tree hugging? Consider me guilty! lol

Best,
Gene

I'm mostly on your side, but do you think the POCO doesn't know what's going into their system ? Knock yourself out, but, you'll eventually get busted by the POCO for financial and what they will say, with justification, are safety concerns.

[J.P.M.]

Looks like NY State law sets the 25 kW limit for net metering, and the standard permitting guidelines are based on DC size, which pretty much kills all the more creative approaches discussed here. It may be worth verifying with the specific AHJ and Poco, but it doesn't look good.

If the OP is willing to forgo net metering, a larger system could be installed, but it is hard to see how that would be cost effective.

Similar to what Jflorey2 writes, I'd size the system right and then use inverters and system design that limit output to the grid at 25 kW or less. Not sure how cost effective or cost ineffective that might be, not to mention increased maint. hassle/PITA.

[bcroe]

Here in the Wild West the PoCo cares about the inverters & AC wiring that feed into their system; over
panelling is not a concern. Your results may vary. Bruce Roe

[GRickard]

Here you are allowed 30kw per meter. Theoretically, if you were to put in a second service for just your HVAC loads, that may allow you to put 25kw on each meter. Extra kwh however will not transfer between accounts. Check your POCO's net metering tariff.

Greg

[peakbagger]

I think the key thing is net metering access. If you want to go bigger you become a merchant plant and I guarantee you the utility is not going to pay you a lot for any surplus and will mostly likely charge you a demand fee on top of any power you need to buy when you are importing. Odds are you need to shell out for a PE to sign off on one line and interconnect application. The utility will probably also decide that they are going to have you pay for upgrades to their system in order for you to interconnect. Heck if they want to be cruel they can hit you up with the cost and cruelty to put in a Direct Transfer Trip and a 3VO protection upgrade to a nearby substation.

Homeowner PV regs usually set up a "sandbox" for the little guys to play in where everyone plays nice, once someone wants to leave the confines of the sandbox, the gloves are off and the cost and complexity to do an interconnect increases exponentially. Some solar friendly states have solar friendly rules for intermediate systems so you may get lucky but doubt you will find a utility that will net meter al large system. Then again Mass seems to do it via SRECs to big developers.