I think I have a valve because after the pump stops I can hear water coming down from the panels for a minute or two. When the pump restarts, for the first couple of minutes only air flows down from the panels and into the pool through the jets---and there is no doubt about that! The explanation of why the valve is needed also makes sense, so I have never questioned this.

I switched to time-of-use because that was required by our power utility (PG&E) in order to sell them energy. We just installed 30 Sharp 170W PV panels (which by the way appear to produce a peak of 4300W, according to the inverter).

I like the cost of electric energy in NJ! But at that price I don't think I would have installed the panels.