Carl from Denver. Client installed a 150 kW rooftop solar array last spring expecting to see major bill reductions. Their energy charges dropped significantly but their demand charges barely moved and in some months actually increased. Client is frustrated and confused. Can anyone explain what is happening?
Client installed solar and demand charges got worse — why?
Walt from Pittsburgh. Solar reduces net energy consumption but does not reliably reduce peak demand. Demand is measured by a 15-minute peak interval. If that peak interval occurs on a cloudy afternoon or before sunrise solar generation does not help at all.
Mike D. The situation can get worse if the solar installation changed any operational patterns. For example if the client now runs equipment during what used to be low-energy periods because electricity feels cheap the peak demand may actually increase.
Jim from Scottsdale. I had a nearly identical client situation. The solution was pairing the solar analysis with a demand response or battery storage analysis. Solar alone rarely solves a demand problem.
The installer never mentioned demand charges at all when selling the system. Just projected overall energy cost reduction. The client feels misled.
Terry. That gap in the installer's analysis is unfortunately common. Utility bill auditors and solar installers often talk past each other. Your job now is to find demand reduction strategies that complement what the solar is already doing on the energy side.