People are not limited to using only the energy within our bodies.  We can use energy from other sources, to enhance our productivity, comfort, and convenience.  

Energy Storage

Energy can be stored, and it can be converted from one form of energy to another.  Energy cannot be created or destroyed by conventional methods.  (Albert Einstein came up with a way to convert matter to energy.  Due to the complexity, cost, safety, and environmental concerns this method is not likely to be used to provide heat and hot water directly for our homes and small businesses.)

Energy Conversion

Frequently energy is stored chemically.  Gasoline stores energy chemically for propelling an automobile.  We use the chemically stored energy by converting it to mechanical energy in the car’s engine.  The conversion process begins when the gasoline vapors are ignited in the cylinders.  Although the desire is to convert the chemical energy of the gasoline to motion, or mechanical energy, burning gasoline in an internal combustion engine results in the desired motion plus a lot of undesired heat.  Heat is another form of energy.  In cars, where we want mechanical energy, we must get rid of the undesired heat.  Most cars have a radiator to dispose of the unwanted heat.

Water Heating and House (or space) Heating

Most homes in the northeast United States use fossil fuel for space and water heating.  (If electricity is used, a portion of the electricity is obtained from burning fossil fuel at a remote location.)  We desire the air in our house and the hot water to have a specific temperature, the set point.  This is usually achieved by adding energy when it is needed.  This means that we must store energy, to be available when it is called for.  If your home is heated by oil, the energy is stored chemically in the oil in your oil tank.  When necessary, this is converted to heat in your boiler or furnace.

Conventional tank water heaters have an additional way to store energy.  The source of fuel stores energy as cited above, and the hot water tank (typically at least 30 gallons) stores energy in the form of heat.  A hot water tank in your basement has standby losses.  When no hot water is being used (when people are away or sleeping) the tank will cool.  After the tank cools, your fossil fuel will be used to heat the water to the preset temperature.

Standby Loss Prevention

Standby losses in domestic hot water can account for as much as 30% of your energy consumption for hot water.  Using fuel to heat water while you are sleeping or out of the building can be prevented.  There are several brands of gas tankless on demand water heaters.  Alpine Solar sells the TEMPRA line of electric tankless on demand water heaters.  These water heaters use energy only when a hot water faucet is turned on.  There is no standby loss from heating water when you don’t need it.

Solar Hot Water

Changing from a conventional tank water heater to a tankless on demand water heater will reduce your utility cost and impact on the environment.  With a good solar location, further improvements can be obtained by using the sun to heat a large tank of water.  A typical single family home will need a 100 gallon solar water storage tank, and one evacuated tube solar hot water collector*.  Many tankless on demand water heaters are set up to sense the incoming water temperature and add only the amount of energy needed to reach your set point.  On a good solar day no gas or electricity will be needed to supplement the sun.  Solar hot water tanks are designed to minimize standby losses.  When the temperature of your solar water goes down overnight, it is a small waste of solar energy, but not a waste of fossil fuel.  Most single family homes and small businesses, which use hot water every day, will have financial benefits after installing solar water heating.

*Note:  Some people refer to a solar hot water collector as a “solar panel”.  “Solar panel” can also refer to  a photovoltaic module which converts solar energy to electricity.  Since the phrase  “solar panel” is ambiguous (it can refer to a device using the sun to provide thermal energy or electrical energy), it will not be used in this website.  Throughout this website: solar hot water collectors provide hot water or thermal energy; while photovoltaic modules provide electrical energy.

Solar House (or space) Heat

Conventional home heating systems use the stored chemical energy in fossil fuel.  It is possible to collect energy from the sun, store the heat energy in hot water, and take the energy out as needed to heat your home.  The size of the water storage tank will determine how long you can go without needing a backup source of heat, and how many collectors will be needed.  A 1,000 gallon tank may be needed.  Such a tank can be built into a corner of the basement.  A cube 5 feet 2 inches on each side encloses 1,000 gallons.

The backup source of heat can be a completely separate conventional heating system which will be used after several cloudy days.  Another approach is to use a boiler to heat the large water tank when the water temperature has gone down due to cloudy weather.  The boiler can be fueled by oil, gas, or  wood.  Firewood is considered by some people to be a carbon-neutral source of energy.

Space heating a home or business presents some challenges which are not a concern in solar domestic water heating.  The timeframe to achieve financial benefit will be longer because more equipment is needed and it is only used for about half of the year.  Another potential problem is too much heat during the summer.  There are many remedies for excess heat including swimming pool heating, mounting towards the winter sun, covering collectors, etc.  Equipment to convert excess heat, in water below boiling, to electricity is not yet commercially available.


It is good that people want to help the environment and save money on utility expenses.  The best place to start is by reducing consumption.  You can live comfortably with less energy by first sealing and insulating.  In western Massachusetts help is available from CET (Center for Eco Technology) and MassSave ( 800-666-3303 for your free energy assessment).  When seeking renewable energy equipment, such as solar, your expenses will be minimized by first reducing consumption.

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