Hi Moataz,
To follow up on Paul's response, the dispatch strategy is set such that battery only charges from PV. As Paul mentioned, if the PV priority is to meet the electric load, then the battery will possibly not get charged up enough.
I observe that when the charging priority is set to "PV meets load before charging battery", that the battery state-of-charge goes down to the minimum on January 1 and occasionally gets charged by a little excess PV. But there isn't ever much excess PV, so the state of charge rarely gets very high. This limits the discharge potential of the battery during the night time. The basics of the algorithm for the manual dispatch controller are described in the document here:
www.nrel.gov/docs/fy15osti/64641.pdf
.
Thanks,
Nick
