WHy are there negative numbers on hourly data for a CSP physical trough?

What are the negative numbers in the hourly data when the fossil fuel backup has been shut off? What are they used for?

Can you change the simulator to start in July instead of January?

Also, according to the data from the simulator, the energy output of my CSP physical trough reaches max output in only 2-3 hours in the morning. How is that possible?

1. If the negative system output values are at night, they are probably to account for the electricity required to operate pumps and/or electric heaters to maintain the field HTF temperature.

2. The simulator start time is determined by the weather file's time convention. If the weather data starts at the hour ending at 1 a.m. on January first (as is the case for the TMY2, TMY3, and EPW files), then there is no way to change the simulation start time in SAM. If your weather file is a July-to-June dataset, then the simulation would follow that time convention.

3. The relative size of the solar field and power cycle along with dispatch values on the Thermal Storage page could cause the system output daily peak to be in the morning during some months.

Best regards,
Paul.