Heat exchanger can't handle solar panel water temperature

J P M and Ampster, thanks for everything

For anything I wrote that you found helpful, you're most welcome. Respectfully, more self education will point the way forward for you better and before any forum or other social media.

A lot of words... If the solar panel fluid is isolated from the pool water, did someone point out that "water" may not be the best choice? Think about shutdown modes.. Freezing... Overheating when the pumps aren't running while the sun is still shining. I looked at a "Duda Solar" dudadiesel system a month ago. Has a good installation manual freely available, might help you gain more knowledge. Forget that it is for home water, i think you are seeking the knowledge there.

Yea, folks with short attention spans sometimes think that. Sometimes things need more than one sentence. Life's a bitch, but sometimes that's the price of completeness. Nice feature: Folks get to ignore what you don't think you need.

To your point about water perhaps not being the ideal fluid for the collector loop, I didn't bring it up because, for the most part, it's not part of the conversation. If the OP has a collector system that hasn't frozen, and plans on using the same system but adding another component to it (a heat exchanger), looks like if freezing hasn't been a problem so far, it won't become one with what he is looking into.

Appropriate solar pool water heating systems are available and have evolved that can be cost effective and also SOMEWHAT freeze tolerant. See Fafco and others for more info.

Solar pool water heating is very low tech. It does not need to be complicated. Information only or something else, that system/site you reference is peddling a product that's way overboard in terms of complexity and price, and anyone who knows anything about the subject sees it for the ripoff it is. I'm calling B.S. on it.

Bernie or anyone else that's curious about the basics: A much better reference and a primer of sorts for pool heating can be found at the Florida Solar Energy Center web site under pool heating. Probably less useful for the U.K. etc., but still informative.

Also see the "Build It Solar" website. lots of info there, but it may need a bit of caution/interpretation.

I'll give you a short answer- save your money on the heat exchanger and just use your panels for domestic HW. Those 2 panels won't raise the temperature of your pool water, they don't produce sufficient BTU's. You can calculate the BTU's stored by your indirect tank, and the BTU's produced by the solar panels. I don't know how many liters of water are in your pool, do the math and you will see your wasting your time and money.
I have installed HX's on pools, they are usually rated at 250K BTU's "PER HOUR" or above depending on the size of a pool and that rating is with boiler supply temps of 85 C.
Two panels will be lucky to produce 120K BTU'S "PER DAY" in optimum conditions.