Last minute system change in panels and system size!

[MajorTom_CA]

Hi folks,

So my installer only just found out about the REC warehouse fire that happened in June, and that my planned REC 460 panels now won't arrive until October (at the earliest) - yikes! So to keep the project moving along they are proposing the following:

The original production was (REC 460, 16 panels): 9,974 kWh/year
The new production (Hyundai HiN-T440NF(BK), 16 panels): 9,675 kWh/year

Because the way my roof is, I can only fit 16 panels.

Should I just run with the Hyundai panels and accept the drop in production? (they are offering a small discount to account for the change).

Note my production with the REC panels was already below my annual consumption so I'm a bit hesitant to drop the production even further below my annual consumption. But realistically, it's a 299 kWh/yr drop in production or 3% annual drop which doesn't seem much (?).

Of course I am looking to PTO before the end of the year to qualify for the ITC before it gets whacked so there is also that to consider.

Am I thinking about this the right way? Does Hyundai make good panels and their panel ratings are reliable? This is the first time my installer has talked to me about Hyundai. They usually use REC which has a good reputation (according to them).

This has been a really trying and long journey....I started it in March 2024

Thanks for any input!!

Cheers

[scrambler]

What inverter are you using (brand, model, capacity), to make sure it is not a limiting factor....

[J.P.M.]

1.) As you write, the difference in system size in terms of rated wattage, 7.36 STC kW vs. 7.04 STC kW, will most likely make a small difference nominal annual production, one system to the other.
2.) Keep in mind that such 12-month consecutive outputs are modeled, not actual, numbers.
3.) Actual system output will vary year to year by something like +/- 10% or more, mostly due to weather. Something like EPA estimated gas mileage for vehicles, modeled PV system annual output will vary. Weather is what you get.
4.) Besides, there are no hard rules that say a smaller system with less total annual output has to be less cost effective than a larger system with greater total annual output.
5.) The smart money goal is most bang per installed STC kW. not necessarily the most bill offset.
6.) The idea of covering an entire annual electric bill as the sole economic criteria is often chasing false economy.

Reality: It may give you the warm and fuzzies and feel like your giving the POCO the finger by zeroing out an annual electric bill, but usually the closer you get to a 100% displacement (or more) of the annual electric bill, the less cost effective the system becomes in terms of $$'s/installed STC kW.

As for the inverter(s) and what Scrambler writes, I'd check that out, but I'd think keeping the same inverter(s) or optimizers on a smaller system will probably not, in and of itself, present a problem.

Time is your enemy. The way things look right now, there may well be a big rush at year's end to get stuff installed before the tax credit expires. Also, that cluster function at year's end will put pressure on equipment and labor availability (and given the way things work, probably build quality as well).
30% of system cost vs. a few % of output reduction seems a no brainer to me.

Take what you want of the above. scrap the rest.