The solar panel pumps are not working,then may be solar panel copper tubes block,may be water not store in feed water tank.

two kinds of solar panel exist. if a solar thermal panel, for hot water or hot air, is not being used then any solar energy landing on it is not drawn away by the water or air. The panel temperature rises depending on the characteristics of the panel and the amount of sunshine. as the temperature rises the panel loses more and more heat back to the atmosphere so that the losses always equal the gains. energy absorbed = energy used (or stored) + energy lost.

Yes but only if you have the right type of panels.

Domestic Hot Water Supply System The Solar Panel system is usually found on the roof, It uses the Sun's thermal radiation to warm up water for the house, the blackened layer absorbs the radiant energy and warms up the water flowing through the pipes. But the Hot water system uses cold water from the cold water supply tank and sinks it to the Boiler, where it is heated, and then the water which comes from the Solar panel system and water which comes from the boiler is collected in a hot water storage tank, to be used later. It is known that cold water sinks down and hot water rises up, and so if water in the hot water storage tank cools down it sinks down and then it is carried through pipes to the boiler to be reboiled.

Yes, they get very hot.