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Our solar production

Posted: Fri Dec 17, 2010 9:35 am
by mwalsh
My system:

27 x SunPower 230W panels
SMA 5000 inverter
All panels on the same pitch, just slightly off directly south and on a 20 degree tilt.

Production figures moved to Google document:

https://spreadsheets.google.com/ccc?key ... y=CPOvlYAD

Re: Our solar production

Posted: Fri Dec 17, 2010 10:17 am
by JPVLeaf
Thanks for starting the thread, MWalsh. Do you also have the cell and module efficiencies for your panels?

I'm very curious because our system has been up an running for approx. 2 mos. and I sometimes
feel like ours may be underperforming given original production projections and hearing your all's
production nos.

Yesterday (12/16), our production was 8.1 kwh (4.3 kw dc). :cry:
Our panels are all west-facing (magn. 257°, true 270°), and on a std. pitch of 19°.
Our cell and module efficiencies are 19.3% and 17.1%, respectively.

This will be great for those of us in the same general area (central/south OC) with relatively similar temps
and cloud cover to compare production nos.

Re: Our solar production

Posted: Fri Dec 17, 2010 10:27 am
by Boomer23
Mine was 13 kWh.

24 215 W panels,facing SSW. I don't recall the roof slope. We're in Irvine, near the University.

Re: Our solar production

Posted: Fri Dec 17, 2010 10:29 am
by mwalsh
JPVLeaf wrote:Thanks for starting the thread, MWalsh. Do you also have the cell and module efficiencies for your panels?

I'm very curious because our system has been up an running for approx. 2 mos. and I sometimes
feel like ours may be underperforming given original production projections and hearing your all's
production nos.

Yesterday (12/16), our production was 8.1 kwh (4.3 kw dc). :cry:
Our panels are all west-facing (magn. 257°, true 270°), and on a std. pitch of 19°.
Our cell and module efficiencies are 19.3% and 17.1%, respectively.

I would think your west facing panels are probably why you're taking the hit. But anyway, our panels have an efficiency of 18.49%. Our inverter has an efficiency of 95.5%, and our design factor is 98.140%.

Re: Our solar production

Posted: Fri Dec 17, 2010 10:42 am
by JPVLeaf
mwalsh wrote:I would think your west facing panels are probably why you're taking the hit. But anyway, our panels have an efficiency of 18.49%. Our inverter has an efficiency of 95.5%, and our design factor is 98.140%.
I hope that's the case ... not some other system/install inefficiency. But, just by scaling down due
to system size, mine was 22% below yours and 33% below boomer's. :( I think I need to run something
like pvwatts and check the effect of west vs. south. But, I thought that would make only a ~10% diff./decrease.

Re: Our solar production

Posted: Fri Dec 17, 2010 10:45 am
by garygid
Production rate (kW):
Dec 16, 09:38, 1200, heavy overcast light rain

System Description:
33 Sharp 225 watt panels as 3 strings of 11 to feed less than 8 kW DC (on a good day) to a single 7050 watt max-output AC SunnyBoy "7000" (SMA, excellent reputation worldwide) inverter, connected through an "info-only" (unnecessary) meter and a disconnect switch-box to a 40-amp breaker at the bottom of my 150-amp (now derated to 110 input) service breaker panel and an old "mechanical" spinning-disc Net Metering meter. (gasp)

Max production of 7050 is only rarely achieved.

Roof faces SSE, about 20º east of south. West of south would have been noticably better. About 20º roof slant, as I seem to recall.

Some morning shade on some of the panels is provided be neighbor's tall trees, so there is a noticable "notch" in morning production for about 2 hours.

Monitoring via RS485 to a small netbook running WinXP and SMA's free data-logging program, taking data points each N seconds. For now, N = 60, or some such, I do not recall. Data for each day is stored in a new file, which can be imported to a spreadsheet program. The logging program can read any of the stored files and graph that day's data. I find the graph of AC Output Power the most useful, but the DC (input to inverter) Voltage and Current are also educational. Total lifetime AC Power production is also available.

Re: Our solar production

Posted: Fri Dec 17, 2010 10:49 am
by garygid
JPVleaf,
Is the West string isolated from the South string, even by diodes, connected to different inverters, or are they both just connected to one inverter?

Tell us about the inverter(s), ... main or micro?

Re: Our solar production

Posted: Fri Dec 17, 2010 10:56 am
by JPVLeaf
garygid wrote:JPVleaf,
Is the West string isolated from the South string, even by diodes, connected to different inverters, or are they both just connected to one inverter?

Tell us about the inverter(s), ... main or micro?
Ours are all west-facing. Single SMA SB4000 inverter. No micro. Also, each panel is connected to a Tigo maximizer module (which may make this all ironic), MM-ES60 ... as part of their wireless energy maximizer system.

note: you might be thinking of occ, who has south- and west-facing panels

Re: Our solar production

Posted: Fri Dec 17, 2010 11:00 am
by garygid
It is very difficult to meaningfully compare daily energy production before looking at power (energy production RATE).

Simple passing clouds can reduce daily production figures, making them difficult to compare.

However, graphs of kW AC power production (on a few days with at least some sunshine throughout the day) will usually show you what your system is capable of doing on a full sunny day (at that time of the year).

Re: Our solar production

Posted: Fri Dec 17, 2010 11:02 am
by garygid
JPV ... yes, occ with W & S, sorry.

Maximizer ... what does it do?

Are the DC strings attached to it, then it to the SMA Inverter?