Hybrid Solar Systems

A hybrid solar system typically uses two solar systems that work together to increase efficiency. A typical (PV) Photovoltaic system (electric) is only 15% efficient. By comparison a car engine is about 35% (efficient – a typical car engine produces heat which is lost.) A PV system is usually designed to produce around 80% of a home’s electricity. With a hybrid system these two usually independent technologies work together so that efficiency is increased and now more than 80% of a household’s energy needs is produced. By combining two systems through a computer, the overall efficiency of 50% can be achieved- and noted this is almost double than use of a single system. However, incorporating two usually independent systems is not inexpensive. A hybrid solar system does need to be designed to work together. There has to be some sort of control mechanism which sends the power where it is needed.

Typically the two types of Solar Systems that are incorporated into a hybrid unit are PV Electric and Hot air. A PV system is installed on the roof which provided electricity for the home or business. Since the Solar Panels are usually raised off of the roof- companies use this space to heat the air under the panels. As the air warms, it heats and rises up the roof. Near the top of the roof the air is ducted inside the attic where it can be used for a variety of purposes. Once in the attic hot air can be ducted into the building rooms directly for heat.

This is very efficient as long as the outside air is cooler than air in the building. So in winter the hot air can offset the overall energy usage. This concept can work well in cooler climates. In the summer months, the system can work in reverse. I the climate is hot the cool night air can be ducted into the building as the air flowing under the panels at night is cooled by radiant heat loss. This is similar to an air conditioning system or even a whole house fan. There may be limitations to using a solar air heating systems though as certain extreme climate regions may reduce their efficiency. In areas of high humidity- direct air systems will probably not work well. However, this does not mean one should not consider this option.

The hot air can also be used to heat water, however- heating water from air is highly inefficient. It is more efficient to heat water near the solar PV panels, which could then be used to heat air through a heat exchanger. Hot water can be stored and used when needed for a variety of uses. Hot water is a useful commodity for daily use, including showers and cleaning. But hot water can easily be used to heat the air in the building as well. Hot water can also be stored in tanks and used when needed. So perhaps an integrated hybrid system is the next wave of the future. It will be interesting to note- if the hybrid systems use air or water to gain maximum efficiency.