A solar water heater leaking on the roof is usually the tank, a fitting or a connecting pipe failing, and the risk is not just lost water but the leak tracking into the roof waterproofing and down into the rooms below. It needs the source confirmed and the roof checked, not just the heater looked at.
Where solar water heaters leak
The common points are the storage tank itself corroding, the inlet and outlet fittings loosening or perishing in the heat, the pressure and temperature relief valve discharging, and the pipe runs between the panel, the tank and the building. Rooftop heat and years of thermal cycling age all of these, which is why leaks tend to appear after a few summers.
Why a roof heater leak is a waterproofing problem too
A leak on the roof does not stay on the roof. Water pools around the unit, finds the weak point in the roof waterproofing, and tracks into the slab and the ceilings below. So a leaking rooftop heater is really two questions: what failed on the heater, and has the water already compromised the roof seal. Both need checking, or you fix the heater and still get a stain downstairs.
How we handle it
We confirm the source on the unit and its pipework, then check the roof around it with thermal imaging and moisture mapping to see whether the water has entered the waterproofing. If the heater fitting or pipe is the fault, that is repaired. If the roof seal has been breached, we seal and test that area too, and restore any damage below, under one accountable party.
Do not ignore a small rooftop leak
A slow leak around a rooftop heater is easy to leave because it is out of sight. That is exactly why it does damage, it soaks the roof build up for weeks before it shows inside. Catching it early keeps it to a fitting repair rather than a roof and ceiling job.