Question & Answer


What's the difference between a Solar Hot Water Panel and a Solar Electric Panel?

Solar electric panels are called solar modules, PV modules, PV Panels, and solar panels. However, solar panel is a term that can be used interchangeably for both hot water heating panels as well as solar electric panels. So caution must be exercised so you're understanding the context in which the terminology is used.

A solar hot water panel converts sunlight directly into hot water. The efficiency of the panels can go as high as 60% efficiency, meaning that 60% of the suns energy is converted directly into hot water. A solar hot water panel does not generate electricity it only harvests heat. The heat is typically harvested by circulating water from a storage tank. A circulation pump is used to pump the cold water out of the bottom of the storage tank up through the solar panels which heat the water from direct sunlight and return it to the top of the tank. As the pump is circulating through the day while the sun is out it can raise the water temperature in the storage system significantly if sized properly. Solar hot water panels are usually 32 or 40 square foot panels that are 4 by 8 foot or 4 by 10 foot. They have a series of black plates which absorb sunlight and convert it into heat energy. These plates have water tubes running through them that collect the heat energy from the sun. The heat is conducted from the plates into the cooler water as it is circulated.  
Take a look at solar water heating Technology, Click Here.

Solar electric panels, PV panels, or Photovoltaic Panels are panels that take photo light (sunlight) and convert it directly into electrical voltage. These panels are not generally used for heating water or home space because they are not nearly as efficient as solar hot water panels. Many of these panels range between 10 to 16 percent efficiency, meaning of all the sunlight that comes into these panels only 10 to 16 percent of the energy is actually converted into direct electricity. This electricity is generally stored up in batteries for use at a later time or as needed. A grid tie interconnect system where the solar panels connect directly into the power lines can also be utilized. The standard PV panels are 2 foot by 4 foot in size, but sizes can vary dramatically. The standard panels typically range from 80 to 120 watts of rated output power.

Solar electric panels are manufactured from silicon crystals which when manufactured in this panel format can generate electricity when sunlight strikes the silicon surfaces.

The bottom line is solar electric panels are far more efficient and effective at generating electricity for non-heat loads. Typical uses for PV panels include anything from water pumping, electronics, lighting, refrigeration, or anything requiring electricity for controlling such as thermostats, heating systems that utilize electricity for fans, blowers, circulation pumps, computers, televisions, microwaves, hairdryers, etc. The water heating panels on the other hand are used to generate additional heat and pump that into storage tanks that can later be utilized for domestic hot water needs including showers, laundry, dishes, etc. As well as home heating through radiant in-floor hydronic heating systems, forced air systems, etc. Many homes that are completely independent utilize both types of panels one for heating and one for generating the rest of the electrical loads in the home or business.