I have at Tesla system with 3 batteries, and I argued during installation to include 8kw of panels situated on the west side of our roof against Tesla ‘s engineering. The panels would only by 72% efficient on the west side as opposed to 74% on the east side (catching the morning sun). But my modeling showed that we would exhaust the batteries in the evening due to the fact that my usage was higher in the late afternoons and it wasn’t offset by any generation of solar panels during those late afternoon hours.
After modeling scenarios based on historical usage PER HOUR, I was able to show that if we had enough solar generation during peak late afternoon hours, we would be able to ‘survive the night’ on batteries until morning solar generation resumed. This means my 14kw solar panels coupled with 3 batteries gets me completely off grid for 9 months out of the year. That’s not bad considering I get 7ft of snow during winter months and I am surrounded by very tall trees.
Optimize on hourly generation not daily, most solar companies use DAILY numbers without a clue on hourly usage. I currently get 0.08$ for every 1$ in electric production, so there is very little benefit in producing electricity when you don’t use it. Optimize your system based on your usage not on DAILY production. If electric companies would give me credit of say 0.90$ per 1$ then the equation changes, but electric companies would rather benefit from your overproduction, be careful as these systems are not cheap!
After modeling scenarios based on historical usage PER HOUR, I was able to show that if we had enough solar generation during peak late afternoon hours, we would be able to ‘survive the night’ on batteries until morning solar generation resumed. This means my 14kw solar panels coupled with 3 batteries gets me completely off grid for 9 months out of the year. That’s not bad considering I get 7ft of snow during winter months and I am surrounded by very tall trees.
Optimize on hourly generation not daily, most solar companies use DAILY numbers without a clue on hourly usage. I currently get 0.08$ for every 1$ in electric production, so there is very little benefit in producing electricity when you don’t use it. Optimize your system based on your usage not on DAILY production. If electric companies would give me credit of say 0.90$ per 1$ then the equation changes, but electric companies would rather benefit from your overproduction, be careful as these systems are not cheap!