01-06-2017, 03:33 AM
double throw/double pull switch to change between grid power and solar power
This solution would work, and might even be "permittable", but it also requires manual intervention; an intelligent grid-tied system means not having to worry about state-of-charge.
Also consider that a (propane-fired) backup generator costs about as much as the SSPP fees, with an operating cost/KWh that's pretty close to grid power. Wire the auto-start circuit up to the charge controller... no HELCO bill, and an extra several KW "on tap" for the occasional need.
This solution would work, and might even be "permittable", but it also requires manual intervention; an intelligent grid-tied system means not having to worry about state-of-charge.
Also consider that a (propane-fired) backup generator costs about as much as the SSPP fees, with an operating cost/KWh that's pretty close to grid power. Wire the auto-start circuit up to the charge controller... no HELCO bill, and an extra several KW "on tap" for the occasional need.