New 4.27 kw system in Oakland

[Guest]

Wow! This one looks good and nice! I am wondering how much is it to install a solar panel so I am checking some forums and reviews! It seems that your work is really nice!

[bcroe]

I think the Dish guys just slap those dishes up there without bothering
with permits. Not sure if a permit is even required for those dishes. They're ubiquitous.

I've since taken that dish down b/c I'm not using it (prior owners put in on there).

There are too many busy bodies trying to make everyone else conform to their ideas. Thats
why I moved here, where the neighbors can't even see my house, and I can't see theirs. Us
HAMs had some problems with antennas in city limits, but the Feds stepped in and said the
antennas will be allowed. Bruce Roe K9MQG

[mikenmar]

OK, so the city inspector signed off, and the system is up and running. Just waiting for PG&E to do their thing.

My inverter panel shows I'm getting about 3.786 kw of AC power, at around 1 pm. Sun is shining bright, no clouds.

Is that about right, or should I be getting more out of this system?

[J.P.M.]

That depends on orientation, irradiance level and temp. for the most part, but may be in the ballpark.

[mikenmar]

That depends on orientation, irradiance level and temp. for the most part, but may be in the ballpark.

Azimuth is 171 degrees.

Re tilt: Out of 14 panels, 4 of them are at 18 degrees, and 10 of them are at 15 degrees.

Re temp: It was probably about 75F when I made that measurement.

Let's assume irradiance of 1000W/m^2.

[J.P.M.]

Azimuth is 171 degrees. Re tilt: Out of 14 panels, 4 of them are at 18 degrees, and 10 of them are at 15 degrees. Re temp: It was probably about 75F when I made that measurement.

Do this: Run PVWatts, with an 8 - 10% derate instead of the default 14%, choose the hourly output option and look for a clear day output close to the day of interest. Check the hourly output and compare. takes about 5 -10 min. You'll probably be close.

[bcroe]

Performance

My inverter panel shows I'm getting about 3.786 kw of AC power, at around 1 pm. Sun is shining
bright, no clouds.Is that about right, or should I be getting more out of this system?

I thought it was a 3800 inverter, so that sounds like you are maxed out. If you are on savings
time, that is about solar noon. Bruce Roe

[mikenmar]

Do this: Run PVWatts, with an 8 - 10% derate instead of the default 14%, choose the hourly output option and look for a clear day output close to the day of interest. Check the hourly output and compare. takes about 5 -10 min. You'll probably be close.

Ah, I hadn't noticed that "hourly" data feature.

Wow, looks good -- I set the derate at 8%, and I looked at one week of historical data on either side of this date (8/7) --and the peak hour of production is still less than what I saw today.

Outstanding! If that's any indication, I should easily cover 100% of my annual usage, assuming the future weather isn't terrible.

[ButchDeal]

I thought it was a 3800 inverter, so that sounds like you are maxed out. If you are on savings
time, that is about solar noon. Bruce Roe

SE3800 is capable of 4,150 watts so not maxed out at inverter

[J.P.M.]

I just did what I suggested for your location. PVWatts estimates ~~ 3400 W +/- some for max. output this time of year at around solar noon. Your 3.786/4.27 = .89. Check PVoutlet for systems near you. What you got seems about right, maybe a bit high. Hope you're not looking for 4270 Watts. It probably won't happen all that often.

[J.P.M.]

Ah, I hadn't noticed that "hourly" data feature. Wow, looks good -- I set the derate at 8%, and I looked at one week of historical data on either side of this date (8/7) --and the peak hour of production is still less than what I saw today. Outstanding! If that's any indication, I should easily cover 100% of my annual usage, assuming the future weather isn't terrible.

Take it all with a grain of salt. Monitoring is probably close, but not usually super accurate. Also, a bit of 1st yr. decrease due to system burn in is possible. Also, PVWatts is still somewhat conservative at times, even w/ the lower derate. What you are seeing is not uncommon to my experience, and another reason to be careful of some vendors' conservative output estimates.

[J.P.M.]

Looks like our posts crossed.

[mikenmar]

I just did what I suggested for your location. PVWatts estimates ~~ 3400 W +/- some for max. output this time of year at around solar noon.

What weather data did you use? When I first plug in my address, it defaults to a location in SF. But this region has serious microclimate variations. SF has substantially more cloud cover compared to Oakland. I switched it to Oakland International Airport, which is the closest location it had listed (about 10 mi away).

Your 3.786/4.27 = .89. Check PVoutlet for systems near you. What you got seems about right, maybe a bit high. Hope you're not looking for 4270 Watts. It probably won't happen all that often.

I'm not expecting 4.27 kw on the AC side, not at all. As nearly as I can tell, that's basically impossible.

If I can regularly hit > 3.5 kw at peak summer hours, that will be plenty for me.

[J.P.M.]

What weather data did you use?

Hayward Air Term. I couldn't get PVWatts to puke out Oakland. In the bigger scheme of things as long as it's not S.F., it's probably close enough.

[mikenmar]

We had a nice sunny day today, no clouds. Here's my production -- almost 28 kwh! I'm pretty happy with that.