The number of solar panels required to run a boiler depends on several factors, including the boiler's power consumption, the efficiency of the solar panels, and the average sunlight hours your location receives. Boilers can vary widely in their power requirements, typically ranging from 3 kW to upwards of 30 kW for larger homes. A standard solar panel might produce around 250 to 400 watts per hour under optimal conditions. Therefore, to power a 3 kW boiler for a few hours a day, you would need a substantial solar panel system, possibly 10-12 panels or more, and a system to convert and store enough solar energy, such as batteries and an inverter.