Improved Solar Pool Heater - Full build

It’s here, a solar pool heater created from all of your comments (Thank You), and it’s a good one, well, as far as I know... The UK summer stretched over a full 2 weeks it seemed, up to when I completed this panel. But, despite this, the new version 2 solar pool heater did better than I expected, reaching an average of 500W in one day, that’s 4kWh over an 8 hour period, plus hit a peak of 640W (measured using flow rate and input to output temperature).