I really enjoy reading the posts on this group

System: 40 SR100 panels in 2 strings of 20 each.

South facing at 30 degrees tilt.

GT 3.8 inverter.

Running latest beta version of GT View. (1.9)

My question is how much power can I expect from this system?

Located in Chico, CA 95926

Thanks,
Chuck Alldrin

I'll make a wild guess that that part # indicates a 100W panel - so you have 4KW worth of panels.
If you have a non-foggy view of the sunrise - sunset, you should do pretty good, I have 4.5KW of panels, about 25deg west roof, and peak can get 3.8 kw out of them. you will get more hours facing south, than I do facing west, you you will net more.
I'd guess, after the panels heat up, you will get 3.5 - 3.8KW out of the inverter. You may need to fan cool your inverter, air movement really helps them.

Chuck,

I think mike is much to generous on the power numbers, my 3400 watt arrays run at about 2200 watts, keep in mind I live in florida which heats the panels and my panels are roof mounted at about 18 degrees

The only way you would see 3600-3800 is on a VERY cold day with the panel being perpendicular to the sun, which at 30 degrees tilt would only be twice a year.

Last week we had some really cold weather, I got up to ~2500 watts, the face the panels are about 15 degrees off from perpendicular this time of year

SG

As an FYI... Unless Solar Guppy knows of a better solar power calculator--while looking through the www.sunpower.com site, I found that they have a pretty nice solar calculator for use with Grid Tie systems.

http://www.sunpowercorp.com/
http://www.sunpowercorp.com/technology/solar_calculator.php

I compared it to my 2 strings of 10 panels BP 4175 with Xantrex GT 3.0 inverter over the last year+ of results, and the numbers seemed to come within about 10% of my actual numbers (I have some morning/evening shading issues especially in the winter months so mine were lower).

It not only lets you plug in orientation (E,SW,S,SW,W), it supports roof angle and (it appears to) supports complex utility rates (Flat, Tiered, TIME OF USE for PG&E E1, E6, E7, gas or electric home). Of course, it does not manage shading or allow you to offset your own time of use power usage.

However, I did test it between two locations--my place on the sunny side of our coastal mountain range and the marine layer side where I grew up (in some areas, you might see the sun once during the entire summer). And I got the same results--so, if you have coastal fog/marine layer or other issues--you may have to derate the power output significantly for your location.

For example, $600 per year electric bill, 3,500 watts of panels SE facing 30 degree roof pitch, San Mateo CA (note: -$79 means that I generated more credits than I used over a 1 year billing cycle--in PG&E--you loose the credits at the end of 1 year net metering):

E1 rate plan: -$79 over 1 year (flat rate residential)
E6 rate plan: -$84 (new TOU with partial peaks to 9pm and weekend PP too)
E7 rate plan: -$192 (old TOU with peaks Noon to 6pm Monday-Friday)

I actually generated about -$285 in credits (E7) because my power bill is closer to $500 per year (not $600 which is Sunpower's lowest option). Planning for AC and/or plug in hybrid in the future).

-Bill