Desperately seeking off grid solution for sunpower 210 panels!

Re: Desperately seeking off grid solution for sunpower 210 panels!

chopkins wrote: »

If the grid is up and the XW is doing a pass through charge of the batteries from the power generated by the GT, will it correctly charge the batteries?
(previous post seemed to indicate that is would not).

As I would understand the XW operation--if the grid is up, it has its own AC to DC multistage battery charger--so depending on how you have the XW configured--it should maintain the batteries just fine from its own internal battery charger (as long as the mains are up).

If that is the case, the secondary charge controller is needed between the XW and the batteries to actually handle the charging duties.

I would not see a need to protect the batteries against the XW's internal battery charger... It should already have several independent methods of preventing a dangerous overcharge of the batteries (assuming charger is properly configured).

If that is NOT the case, the XW will handle all the battery charging duties and the secondary is then in parallel and is only used to detect battery overcharge (backup).

The issue is when the XW is Off-Grid (mains down) and it is being "back driven" by the SunnyBoy (or equivalent) Grid Tied inverter... There is no control/feed back circuit in the XW to control the battery bank's state of charge--other than (I think) the over-voltage detection circuit on the XW inverter's DC input--same thing if the battery bank went over-voltage for any reason while the inverter is running--forwards or backwards--and is probably intended to protect the inverter's electronics from failure--and is not intended to protect the batteries).

-Bill