About to install LG300A1C-B3 300W AC microinverters, got some Q's

[AaronG]

In general, because the panel array will rarely if ever produce its full STC rated output, some overpanelling of the inverter (like 6300 into 6000) should not be a problem. The question is what the next size up of SE inverter is and what the cost difference is. I would definitely not recommend a system with two SE string inverters just to avoid clipping.

I can't really fit any more panels than this on my roof, so I wont be expanding the system in the future. Perhaps if I am in the home 20 years from now and panels are cheap as hell (unlikely) producing 600w a panel, then we'd toss out the whole system and replace it. But ya, as far as thinking that maybe I go to a 7600 because I may add more panels, isn't happening.

It sounds like I am OK with the single 6000. Thank you!

[thejq]

I can't really fit any more panels than this on my roof, so I wont be expanding the system in the future. Perhaps if I am in the home 20 years from now and panels are cheap as hell (unlikely) producing 600w a panel, then we'd toss out the whole system and replace it. But ya, as far as thinking that maybe I go to a 7600 because I may add more panels, isn't happening.

It sounds like I am OK with the single 6000. Thank you!

The next step up which is SE7000A-US is about $100 more http://www.wholesalesolar.com/solaredge.html. If you really want a peace of mind and maybe somewhat better longevity, it's worth considering.

[AaronG]

Looking at the manual for the SE6000-US it shows
Maximum AC Output = 6000w
Recommended Maximum DC Input Power = 7500w

It's next to impossible to see 300x21 at 6300 DC watt output from my panels (input to the inverter). There will be loss along the path and loss inherent in the inverter. So even *IF* I had 6300W going to the inverter and the inverter output 6000W that would be 95% efficient. My reason thinks that if there was more panels like 23-25 and we were pushing 7k+ area we could see possible clipping. but at 21, it seems highly unlikely we'll ever run in to this, right? I am still totally within the recommended maximum DC input (7.5kWh).

Also, I have a 20-year warranty on the inverter. Sure I'd love it to last long after I am dead (I am only 36), but after a replacement I think It'd prob long outlast me in this home. I plan to retire to the Caribbean before I am 60, hahah

Also I dont see the SE7000-US anymore directly on SE site. It may be an older product? If you look on their site here, it isn't listed:

http://www.solaredge.us/groups/us/products/pv-inverter

Also, this PDF doesnt show it either:

http://www.solaredge.com/files/pdfs/products/inverters/se-single-phase-inverter-datasheet.pdf

Any thoughts guys?

[sensij]

As others have said, whatever clipping you will see will add up to very little. Also, keep in mind that the 6300 W is year 0 power. These panels will break in a % or two in the first year, then drop maybe 0.5% annually after that. Even if they are high on the power tolerance (+ 3%), whatever miniscule amount of clipping occurs will be less every year, and should be gone by year 10 or sooner.

[thejq]

I'm sure you'll be fine with SE6000. I just thought for $100 more, why not. But if you can't find SE7000, there's no point spending $700 extra for SE7600. FWIW, I like to run things under its rating.

[sensij]

The SE7000 is a real product, but only puts out 6000W at 240 V. It isn't clear what the extra $100 would be buying here.

FWIW, a quick run of 22 -G3 panels using SAM defaults (20° tilt, 180 azimuth, san diego TMY2) yields 11841 kWh annually using the SE7600A, and 11826 kWh using the SE6000. The hourly chart shows a few days with clipping in April and May, but for only around an hour at the peak of the day, 14 hours total in the year. -B3's aren't in the database yet, and I can't figure out how to make one string of 10 and the other of 11, so please just consider these numbers illustrative. Depending on the details of the actual installation, the results will be different, but really, there is nothing wrong with the SE6000 in this case.

[AaronG]

The SE7000 is a real product, but only puts out 6000W at 240 V. It isn't clear what the extra $100 would be buying here.

FWIW, a quick run of 22 -G3 panels using SAM defaults (20° tilt, 180 azimuth, san diego TMY2) yields 11841 kWh annually using the SE7600A, and 11826 kWh using the SE6000. The hourly chart shows a few days with clipping in April and May, but for only around an hour at the peak of the day, 14 hours total in the year. -B3's aren't in the database yet, and I can't figure out to make one string of 10 and the other of 11, so please just consider these numbers illustrative. Depending on the details of the actual installation, the results will be different, but really, there is nothing wrong with the SE6000 in this case.

Wow thats great info you shared, thank you. really thanks a ton! very cool
Isn't 180 direct south like the most ideal. So you technically will see better yields than I could possibly at my azimuth.
Here's a pic of my plan submitted.
solar.jpg

[J.P.M.]

The SE7000 is a real product, but only puts out 6000W at 240 V. It isn't clear what the extra $100 would be buying here.

FWIW, a quick run of 22 -G3 panels using SAM defaults (20° tilt, 180 azimuth, san diego TMY2) yields 11841 kWh annually using the SE7600A, and 11826 kWh using the SE6000. The hourly chart shows a few days with clipping in April and May, but for only around an hour at the peak of the day, 14 hours total in the year. -B3's aren't in the database yet, and I can't figure out how to make one string of 10 and the other of 11, so please just consider these numbers illustrative. Depending on the details of the actual installation, the results will be different, but really, there is nothing wrong with the SE6000 in this case.

I thought the orientation was WSW ? Also, Miramar (preferable) or Carlsbad airport may be more rep. than San Diego, FWIW.

[sensij]

Wow thats great info you shared, thank you. really thanks a ton! very cool
Isn't 180 direct south like the most ideal. So you technically will see better yields than I could possibly at my azimuth.
Here's a pic of my plan submitted.
[ATTACH=CONFIG]5009[/ATTACH]

Yes, exactly. The simulation conditions are with a bigger system in better sunshine and with better panel orientation. So to the extent that a simulation run by a random person on the internet can be trusted, your system will have even less clipping. SAM is free if you'd like to run your own simulations, although some concurrent time with the documentation might be well spent.

[sensij]

I thought the orientation was WSW ? Also, Miramar (preferable) or Carlsbad airport may be more rep. than San Diego, FWIW.

Good point, Miramar would be a better test. That would bump it up to 12267 kWh output, with 9 hours of clipping. One interpretation is that more sun in Miramar brings the overall output up, but warmer temps cut down slightly on the peak power hours.

[AaronG]

Yes, exactly. The simulation conditions are with a bigger system in better sunshine and with better panel orientation. So to the extent that a simulation run by a random person on the internet can be trusted, your system will have even less clipping. SAM is free if you'd like to run your own simulations, although some concurrent time with the documentation might be well spent.

That is a really cool tool. I plugged in my area, set the tilt, azimuth, and got sdge rates, etc. and then ran some simulations. very neat. There are so many dang metrics though. I dont think I'll put in the time to try to master this tool, but I can see how valuable it could be. It'd be neat to see someone who knew this thing perfectly run through some scenarios with me. oh well, no biggy. Still, neat tool. Thanks... Up until now I only knew about PVWatts.

[J.P.M.]

That is a really cool tool. I plugged in my area, set the tilt, azimuth, and got sdge rates, etc. and then ran some simulations. very neat. There are so many dang metrics though. I dont think I'll put in the time to try to master this tool, but I can see how valuable it could be. It'd be neat to see someone who knew this thing perfectly run through some scenarios with me. oh well, no biggy. Still, neat tool. Thanks... Up until now I only knew about PVWatts.

Be careful on SAM's SDG & E rates. I haven't checked the newest SAM rev's but the rates on the prior rev. were WAY off. I'd bet if correct they are still an approx. due to complications of SDG & E rate fine points. Maybe they've been fixed. I've been using SAM for several years and will download the BETA version once I'm convinced the bugs/crap are puked out. Great tool, but it does strange things at times.

[J.P.M.]

Good point, Miramar would be a better test. That would bump it up to 12267 kWh output, with 9 hours of clipping. One interpretation is that more sun in Miramar brings the overall output up, but warmer temps cut down slightly on the peak power hours.

Agreed. BTW, on temps. - one thing I've known as a blinding flash of the obvious, but more firm in my mind as a result of all the panel fouling measurements I'm doing is that my air roof temps at min. incidence angle on the array and probably to a lesser degree all day are about 8 to 12 deg. F warmer than the ground ambient or "porch" temp. That's good for my roof only, but I'd suggest it's likely for a lot of other locations as well, at least to some degree. .

[sensij]

Be careful on SAM's SDG & E rates. I haven't checked the newest SAM rev's but the rates on the prior rev. were WAY off. I'd bet if correct are still an approx. due to complications of SDG & E rate fine points. Maybe they've been fixed. I've been using SAM for several years and will download the BETA version once I'm convinced the bugs/crap are puked out. Great tool, but it does strange things at times.

In the new beta version, the biggest problem with the SDG&E imported rates is that the Baseline and Tier values are based on kWh per day, when all of SAM's calculations are done based on monthly usages. The tiers need to be scaled to an average monthly level for winter and summer to get results that make sense. The actual $ / kWh are reasonably accurate.

There are a few other bugs... fields that should accept decimal numbers that don't, and some of the automated sizing routines seem flaky. Actual calculations have appeared solid so far.

[J.P.M.]

In the new beta version, the biggest problem with the SDG&E imported rates is that the Baseline and Tier values are based on kWh per day, when all of SAM's calculations are done based on monthly usages. The tiers need to be scaled to an average monthly level for winter and summer to get results that make sense. The actual $ / kWh are reasonably accurate.

There are a few other bugs... fields that should accept decimal numbers that don't, and some of the automated sizing routines seem flaky. Actual calculations have appeared solid so far.

Do they have the DWR bond charge and misc. taxes in them yet ? Missing before. Also, one of the bigger problems w/ SAM's rate structure, besides inaccurate or completely missing energy charge portion was the 20 different billing schedules SDG & E uses with varying # of days/billing period (29 to 32) that rarely conformed to or start on a calendar month and that changed every year on top of that.