Help and advice please on re-use of solar hot water panels

[RoyInFrance]

1- You can run off 12v PV with a solar panel and 12v dc pump = no control when the sun hits the panel the pump will start to run slowly reaching full speed when full sun hits the panel. This usually works for 1 small 32sq.ft serpentine panel or evacuated tube system. If you have flat plate standard header and tube panel or multiple panels it would be hard to find a dc pump to give you sufficient g.p.m flow rate to make this work.

2- This in my opinion is the most desirable option. If power is lost the panels may stagnate but that should not be a problem if the expansion tank is sized properly. The controller will just resume when the power comes back on, no reset required.
Or convert to a drain back system. This is the only type system that I install because of it's simplicity, no glycol, no expansion tank. Search for solar drain back system .

3- See #1

I have 4 usable water panels approx 53" x 33" (one I suspect was damaged .) All with 15mm pipework so probably 48 Sq ft Panel and Flow Meter.pdf
I have found DC pumps and panels but all are submersible pumps (3.2 GPM and 230 ft lift) - good for drainback systems but no good for closed loop glycol.

I have started to read up on drainback systems, with solutions from simple to very complex How could I transfer the heat from the drainback system to the hot water tank? can you point me towards a simple design..

Also Is the flow meter of use to me in either setup?

Thanks.
P.S. please advise if I am asking too many questions

[LucMan]

Try this, all of the different type systems illustrated here for your info.
https://www.aetsolar.com/cfiles/dfil...5Optimized.pdf
https://www.aetsolar.com/literature-download
If you have a flow meter use it, it's not required but could help tp make fine adjustments to flow rate.
Happy reading

[RoyInFrance]

OK. Thanks for all the information, Now I need to do calculations e.g. how much electricity am I using each night to power my immersion heater vs how much to run AC pumps to use solar, how much to invest in PV solar to power pumps etc AND to find UK or French suppliers.

All this then I can calculate the investment and pay back time. Not much point in doing all this work if it will take years to get the cost of investment back.

Lastly, Where can I find instructions on how to use the flow meter Panel and Flow Meter.pdf