Abstract: A modular thermal solar panel water heating system with a plurality of solar heating modules, each including a inlet manifolds and outlet manifolds and a thin tube array disposed between and in fluid communication with the inlet and outlet manifolds. Mounting and clamping apparatus attach the solar heating modules to a surface and providing secure clamping pressures on clamped elements even as clamped elements expand and contract. Fittings provide a watertight coupling between adjoining modules and bring each module into fluid communication with at least one adjoining module. In a panel array, one module includes a water inlet for connection to a source of water under pressure and another module includes a water outlet. A set of plugs are disposed on the manifolds in a configuration that ensures that water introduced into the water inlet flows across at least one thin tube array before exiting the water outlet.