Pump run time with SWG and Solar

[BW]

I recently switched from liquid chlorine to SWG. Electricity is expensive in my area, so I opt for healthy sized filtration and SWG, and keep the pump run time to ~4 hrs a day. I had everything nicely balanced with my new SWG producing correct levels, then the weather changed for a few days and my solar controller decided to "extend" the pump time to heat all day. Of course with this extra pump time, the SWG ended up producing way too much chlorine. I assume the solar controller adjusting run time for heating demand is a common feature, but it doesn't seem to play well with SWG that needs predictable run time. I suppose the answer is to run the pump all day and turn the SWG output down, but I'm wondering if there are other solutions. I'd prefer to keep my nominal 4 hr run time if possible.

 

[ajw22]

@Dirk runs solar in your area and I am sure has thought through the issue.

 

[Dirk]

I run my pump 4 hours a day in the off season, and 8 hours a day in the swim season, to satisfy my solar heater. My SWG provides the required FC in both scenarios.

While I could run my pump less in swim season, and I'd get enough FC, I wouldn't get enough heat, so that's why the eight hours.

My pool automation system controls everything, including solar. But I set the runtime, the controller doesn't override that based on thermostat setting. What solar controller system are you running? (you should add that to your signature.)

I installed a PV solar system years ago. It has since paid for itself. I don't pay for electricity, so I run my pump to keep my pool clean and warm, and don't consider electricity costs. If you plan on staying in the current house, that's where you should look to save on electricity costs. The adage goes "Today is the best day to invest in solar, it'll only be more expensive tomorrow." And PG&E will continue to raise its rates. Once they coerce enough of us to supply their grid with our solar, they will begin to eliminate incentives for solar (as will the federal gov), so the whole financial picture for solar will just get worse and worse.

If you can heat your pool satisfactorily in four hours, then do that. Sort out the controller so it adheres to your schedule (as in: check the manual). If you supply the model, maybe I can help.

 

[BW]

Thanks for the detailed response Dirk. My solar controller is the Hayward E-Command 4, which I believe is their basic automation system. The "solar extend" feature seemed logical, but maybe it's not that common. As you know the heating time varies dramatically throughout the season. Spring and fall it's going to take every minute of full sun, while mid-summer with the cover on, the solar is on less than an hour. Anyway I think the answer is clear, turn off the solar extend and do a fixed run time. Maybe 8hrs in spring and fall, and 4hrs mid-summer.

As for the PV solar, I'm with you. I was short on sunny roof area until a big tree was removed recently. Now I've got no excuse.