On-site Fuel Cells

I do not think so. Typically they are not even a renewable energy source as they usually use natural gas as the primary fuel source. Their energy use/cost impacts could contribute toward EAp2/EAc1.

Maybe we do not have the same understanding of what a fuel cell is/does. In my understanding it does chemical reverse electrolysis of water, combining hydrogen and oxygen to make electricity and water. So there is no storage in a fuel cell per se. The storage medium would need to be something like hydrogen. You can use the solar electricity do the electrolysis of water and store the hydrogen. More commonly the solar electricity would be stored in batteries for use at night, especially in an off-grid system. So if you are storing the solar electricity and using it at night then that just extends the use of the solar power. This benefit is already addressed within EAp2/EAc1 so would not qualify for an ID credit. Let me know if my understanding of what you are proposing is incorrect. Keep in mind that you earn ID credits, typically, for addressing an issue that LEED does not address. So if it saves energy or results in renewable energy use that is already covered. ID credits are not usually about doing something innovative, often confusing folks due to what they are called.

You can certainly earn an exemplary performance ID credit related to EAc2 is you attained 15% renewables. You can do this even using old technology!