Filling the roof is not the same as getting a return. How to read a load profile and pick the capacity that pays back fastest.
A common mistake when investing in rooftop solar is to size the system from the available roof area. The correct starting point is the plant's daytime load profile.
Why roof area is the wrong input
Solar output peaks between 10 am and 2 pm. If the plant load in that window is lower than the generation, the surplus has to be exported or curtailed — and the payback period stretches out.
Three steps to the right capacity
- Log hourly average load for at least one month of normal operation.
- Take the base load in the 10 am – 2 pm window as your self-consumption capacity ceiling.
- Check that roof loading and usable area can actually carry that capacity.
