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mwalsh

Well-known member
Leaf Supporting Member
Joined
Apr 22, 2010
Messages
9,781
Location
Garden Grove, CA
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=0AnSYHt_rpvYydHhpdHdwTEtLX0taeDZyXzdFY0QxWGc&hl=en&authkey=CPOvlYAD
 
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.
 
JPVLeaf said:
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%.
 
mwalsh said:
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.
 
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.
 
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?
 
garygid said:
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
 
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).
 
West facing at 270º will get no direct sun until after "sun-noon", so the direction is rather sub-optimal. Your expected DC production is likely to be only 50% of the panel's ratings.

VERY GOOD TOOL:
Have you used (played with) the on-line expexted-energy calculator, provided by the folks that calculate the CA Rebate for a PV system?

A copy of its results should be included in your copy of the Rebate paperwork.
 
garygid said:
West facing at 270º will get no direct sun until after "sun-noon", so the direction is rather sub-optimal. Your expected DC production is likely to be only 50% of the panel's ratings.

It's not so bad. West facing shifts the peak time a little later compared to South. The CSI solar calculator can tell you how much you're "missing" in the winter compared to those south-facing guys (who will have something "missing" in the summer when the sun is more directly overhead).

http://www.csi-epbb.com/default.aspx
 
garygid said:
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?

Looking at the spec sheets, it looks like a circuit breaker for each panel that is controlled wirelessly to switch panels off like a diode when they are not adding current. It is controlled by a centralized processor monitoring the panels.

http://www.atensolar.com/m5/200-225--tigo-energy-module-maximizer-series-30-110vdc-mc4-in-mc4-out-5a-300w-wireless-es110v300w-4w.html

http://www.atensolar.com/m5/200-258--tigo-energy-maximizer-management-unit-wireless.html

However, I may be misinterpreting it, as they use some marketing terms that make the datasheets a little confusing from a technical perspective.
 
5.8kW DC 28 Kyocera 210W
Sunnyboy 8000
Location Lancaster, Ca
South Facing

Sunny Portal Info Report for plant for the 12/16/2010
Daily Production: 25 kWh
Daily Power (max.): 4.55 kW
 
chris1howell said:
Daily Production: 25 kWh

I'm so jealous! I take it you had clear skies all day yesterday? I can't wait to see what I get for our first day of all-day sun. If there ever is one again, now I have a system! :lol:

I've only estimated 26kWh for a full on summer's day. So if I can get even close to that on a winter's day, and blow it away completely in the summer, I'll be laughing all the way to the bank! :D
 
My 3.24 kW system had a max of 22.8 kWh on it's best day in late May earlier this year. That month also had the highest average output I've seen at 19.5 kWh/day. It was nice and cool and sunny month - only a couple days under 20 kWh.

Have only had a couple months under the expected PVwatts output so far (system has been running since late March) - July and August. Both months had an abnormal amount of cloudy days.

So unless your panels aren't mounted towards the south - I'd expect your peak production months to be late spring and early fall (lower temps = more production). And with a 6.2 kW system I'd expect you to get around 40 kWh on your best days.
 
My system:

4kw DC
20 200watt Sanyo HIP-200B11 panels:
10 facing South ~176deg, 10 facing West orthogonal to the South's
18deg roof inclination
Fronius 4Kw IG4000 Inverter, grid tied (94% efficient, fan cooled)

Max engery output so far was Aug 26, 2010 - 26.66kwh AC
Max power was Aug 26, 2010 - 3.33kw peak.

http://solarweb.fronius.com
Username: public
Password: public
PV System: Tustin0 (QT)

December 17th, 2010: cloudy and rain all day: 3.07kwh
 
JPVLeaf said:
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.

JPV, since your roof pitch and location is close to mine (Tustin Ranch, near Peter's Cayon and Irvine Regional park), and your DC system 4.3Kw is similar to my 4.0Kw, you'd expect the output to be the same. However, I noticed all of your panels are facing west, that would reduced the efficiency a bit.

Also keep in mind, for much of OC summer, the inversion layer doesn't burn off until ~11am to 12noon sometimes, so the South vs West orientation doesn't make a whole lot of difference. For the Winter and Spring, where we don't have the inversion layer, and we get direct sun in the morning, then South vs West is more noticeable...but since Summer is when the day is the longest, West facing system isn't all that bad at all in comparision with South's...at least here in the OC.
 
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