Yes and no. It gives you an idea of average production. What it does not tell you at all is the day-to-day reality, which can be dramatic (check out the screen shots I posted in my comment).
I used PVWatts and other tools extensively while designing my system many years ago. They are helpful, yet, again, none of them expose you to the reality of living with solar. In statistics, it is well known that applying averages to the entire population is a bad idea. Any single day, you can have one cloud kill half your system for hours. You'd be surprise to learn how often clouds --not even rain-- cause you to have to buy energy at the most expensive rate of the day. You quickly learn to hate clouds.
robomartin|2 years ago
Yes and no. It gives you an idea of average production. What it does not tell you at all is the day-to-day reality, which can be dramatic (check out the screen shots I posted in my comment).
I used PVWatts and other tools extensively while designing my system many years ago. They are helpful, yet, again, none of them expose you to the reality of living with solar. In statistics, it is well known that applying averages to the entire population is a bad idea. Any single day, you can have one cloud kill half your system for hours. You'd be surprise to learn how often clouds --not even rain-- cause you to have to buy energy at the most expensive rate of the day. You quickly learn to hate clouds.