I’d like to know if I can change the strategy of model. For example, in my model, when the SOC is about 40% the Fuel Cell starts to run, to feed the load. But, in our pilot project, the FC starts to run when the bus dc voltage goes down of 48Vdc. Moreover, in the other words, when the PV system doesn’t serve the load, because it doesn’t have enough sun, the FC starts first. Then, when we don’t have H2 stored, the batteries serve the load.  Is it possible to change this in HOMER?

If HOMER chooses to discharge the battery before running the fuel cell, it’s because the battery produces power more cheaply than the fuel cell.  (You can verify this by looking at the fixed and marginal costs that appear in the battery and fuel cell tabs of the Simulation Results window.)  If the batteries were more expensive or the fuel was cheaper to operate, HOMER would use the fuel cell first, then the battery.