Jamesq is correct, particularly if the hotwater use is for space heating, which usually requires hotter water (130-160 f) This requires sealed unit heat pipe type collectors which aren't much cheaper than PV. In addition PV gets more efficient with cold (.38% per kelvin) while solar hot water gets less efficient. Soon you get to the point where collecting electrons and running a heat pump is a better bet.
In Brazil, the need for heating is small, the need for domestic hot water then becomes the dominant use. This is almost trivial to do with a large coil of black plastic pipe laid flat on a roof. In use, you actually need to use PEX pipe. YOu can melt standard black poly.
I would suggest 1000 feet of black PEX pipe, split into 100 or 83 foot chunks, and a manifold at each end. This reduces the resistance of trying to push water 1000 feet. (10 pipes will each be 1/10 as long, which gives 1/10 the drop. In addition the flow velocity will be 1/10 as much. Net effect: 1/100 the pressure needed to get the same flow. Ball park figures. Even 5 pipes of 200 would likely be enough.
Now a small solar powered pump circulates water between the pool, jacuzzi. I'd suggest having some form of spill from the jacuzzi to the pool, and pump from the pool to the jacuzzi. This gives you the freshest hottest water in the jacuzzi.
You also should have a large display thermometer for the current temperature. I've heard of people getting their entire pool too hot to swim in.