Solar hot water panels are great because they provide free heat – but usually they provide this heat when you need it the least (summer), and when you need it the most on cold winter days/nights, the sun is not shining much.
So you actually run into the problem of having too much heat in summer (or even warmer spring/autumn days), with nowhere to send it.
We recommend the integration of solar hot water panels only if you plan to heat your pool (this way the excess heat in summer can be dumped into the pool instead of wasted).