REMOTE OPERATION

The overall efficiency of our hydrogen loop equals eff(electrolyzers) x eff( fuel cell) = 0.18 x 0.4 = 0.07, or 7%. That is, the PV array has to put in 14 kW of power for every 1 kW available at the plug. (A different electrolyzer would double efficiency). This would be unacceptably low, except that we do not occupy the house continually, and we are able to run the electrolyzers when we are not home. This vastly increases our hours of PV power, and ensures that the hydrogen tank is full when we need it.

To enable this remote operation, we have a series of relays which respond to PV and battery voltages. When the batteries are full and the PV array is delivering high voltage (eg mid-morning), the electrolyzers turn on. When the PV array output drops, the electrolyzers turn off. We also have a series of voltage monitors that allow us to track the system performance via internet. The monitoring system is still buggy.

A full-time residence would probably need a larger PV array, a larger, more efficient electrolyzer and a larger storage tank. This would ensure that hydrogen production was fast enough for the increased fuel cell use.

Above Left: In the top panel are modules for monitoring the system voltages. The white cubes in the bottom panel are the relays for remote operation. (Photo taken during installation)