Solar Panel Water Heating Efficiency

Photovoltaic modules are tested at a temperature of 25 degrees c stc about 77 degrees f and depending on their installed location heat can reduce output efficiency by 10 25.

Solar panel water heating efficiency.

It may seem counter intuitive but solar panel efficiency is affected negatively by temperature increases. Don t choose a solar water heating system based solely on its energy efficiency. The higher the solar fraction the greater the solar contribution to water heating which reduces the energy required by the backup water heater. The values range from 1 to 11 with most residential systems having a water heater efficiency of 2 or 3.

Bear in mind that the system should be able to provide most of your hot water in summer but much less in winter. Typical solar factors are 0 5 0 75. The solar fraction varies from 0 to 1 0. Therefore cooling by water was found to be more effective than cooling by air.

How much you can save depends on the type of water heating system you are replacing. As the temperature of the solar panel increases its output current increases exponentially while the voltage output is reduced linearly. The sef is the energy delivered by the system divided by the conventional energy input energy used by the backup heater plus any energy used to power pumps or controllers in the solar water heating system. Using air as a coolant was found to decrease the solar cells temperature by 4 7 c and increases the solar panel efficiency by 2 6 while using water as a coolant was found to decrease the solar cells temperature by 8 c and the panel efficiency by 3.

Savings with a solar water heating system are moderate.