Can Solar Electric Panels (PV) be Used for Water or Space Heating?

the midday sun directly heating a large body of water

Yes, but there's a much better way...

Photovoltaics (solar electric panels) convert the sun’s energy into electricity at a relatively low efficiency level (16-19%), so trying to operate a high-power electric heating element with electricity produced by a solar electric panel array would be very inefficient and expensive.

Solar thermal and passive solar design are the best methods for the direct heating of air or water from the sun’s energy, and is much more efficient (55-85%) for heating applications than solar electric panels.