What's the Difference?
Solar electric systems are completely different from solar water heating systems in almost every way.  The only thing they have in common is that they both collect energy from the sun.  

Solar Electricity Systems
Solar electricity starts at the Solar Panels (see also Solar Panels).  These panels are often located on the roof and are full of solar cells that convert the Sun's energy directly to electricity (see also How Solar Works).  They use "semiconductors" and "quantum physics" to absorb light and release electrons that become an electric current. 

But you don't need to know all the details of that.  Just like you don't need to know how your engine runs to be able to drive a car.  You just need to know how to use it.  And you already know how to use your electrical appliances and lights in your home. 



What is important is that the electric current created by a solar electric system can be used to power your home.  Fortunately, the solar electric system is automated.  It turns itself on when the sun comes up and turns itself off when the sun goes down.  It converts the electricity to the same type that your home uses (see also Type of Electricity).  It knows to automatically use the power made from your solar panels when the sun is up and to use the utility company's electricity when the sun is down (see also article on Net Metering).  There is not much for the owner to do.  It would be difficult to make it much easier to run a solar electricity system. 

Solar Water Heating Systems
Solar water heating is a even simpler.  At least, no quantum physics are needed.  A liquid fills a collector that sits on the roof or some other exposed area.  This liquid then is circulated to heat your water (in some cases the water to be heated is itself circulated, like is often done for pool heating). 

This solar heated water can be used to heat your pool or your home's hot water.  For home hot water heating (for showers, dish washing, etc.) water can be used to "preheat" water before it goes into your regular water heater.  This is to reduce your water heating bill.  Also, home solar water heaters usually require an extra tank to store the heated water in addition to your regular water heater.  So you need the space for this tank. 

With solar water heating you have to be very careful that there are relief valves, drainage valves, and antifreeze protection to protect the system from freezing and overheating which can destroy the collectors. 

How to Choose:  Solar Electric or Solar Water Heating
Look at your gas and electric bill.  How much of it is for electricity and how much of it is for gas?  If you are like most people your gas bill is a small part of the total bill and your electric bill is much larger.  So where would you prefer to save money?  On the relatively small gas bill or the more substantial electric bill?  I'll bet the electric bill gets your attention.  If this is the case then solar electricity could be the right choice. 

Solar electric systems typically cost quite a bit more than solar water heating systems, but they also typically save a lot more money on your bills and pay for themselves very quickly (see also Solar Electricity as an Investment and System Sizing). 

Imagine getting rid of 50%, 80%, 90% of your electric bill with solar electricity.  Would that be valuable to you? 



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Robert Morse
BSEE, MSEE
SunCal Solar, Incorporated
www.SunCalSolar.com