Finally up and running

Re: Finally up and running

It is all weather dependent as to what is good one day or the next...

Here are a couple places that have been linked to numerous times... This first one is an average of over 20-30 years of data. I like the PDF files because they also give variance bands of the average per month and per year. It kind of makes me relax a bit when I can see a two to one ratio for winter month daily collections over multiple decades. I don't freak out over one December where my 3.5 kW (3.0 kW PTC Grid Tie rated) array generated 134 kWhr and the next year, December did 213 kWhrs.

The second link lets you calculate your average months/year based on your panel's physics and size. For my area (SF, CA), the predictions for winter months are a bit high (i.e., 246kWr vs 134 and 213 measured for two years) and for summer months a bit low. The overall is about dead-on.

I just keep an eye on the "local" peak days and make sure that they all sort of agree (right now, around 11-12 kWhrs on cool sunny day--although, there have been dark rainy days where I do not even get 1 kWhr). In the summer, my peak days are around 15-17 kWhr--but once in a while I can get 19 kWhrs.

Watching/logging the peak days gives you an idea that everything is just fine (you won't make your peak days if there is a dead panel/string/failing inverter). Fretting over the lesser days with less clear skies (and/or warmer weather)--there is nothing you can really do (other than maybe washing your panels...).

-Bill

For LA CA, Feb. with a 5.1 kW (peak stc name plate) system, you will average 562 kWhr/FEB or ~18.7 kWhrs per day... So, I would guess your weather has been a bit cloudy for a few of those days. Or, you have some other issues (shading, site orientation, etc.) that I have not accounted for in my first guess. But, it sounds like you are off to a good start.