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Solar Domestic Hot Water
Systems
Solar Domestic Hot Water Collectors
Solar Domestic Hot Water systems are the most popular form of
solar energy use: the panels (collectors) absorb the energy
from the sun in order to heat residential water or to
acclimatization goals... The main use of Solar Hot Water
Collector is to heat the water used
in baths and in other domestic uses. But the system can also by
applied to heat water in pools, heat the residential air, or for
cooling the buildings.
We shouldn't confuse the Solar Hot Water systems with the PV (Photovoltaic) solar power systems,
applied to electricity production.
Storage tanks and panel solar collectors
Small systems - systems with 3m2 of collectors - do not
come with a storage tank, but most solar water heaters have an
inside home insulated storage tank (for cloudy days and the
hours of
increased demand) and additional outlet and inlet connecting to
and from the collector.
Two types of solar water heating systems
There are two main types of solar water heating systems:
1) active (with circulating pumps and controls) and
2) passive (without circulating pumps and controls).
Passive systems are less expensive, but have severe limitations.
The active solar water heating systems may involve:
- Indirect circulation systems, with pumps injecting
non-freezing fluids and heat exchangers. These systems are
popular in cold or very cold climates, with freezing
temperatures.
- Direct Circulation Systems, popular in warm and temperate
climates, which do not involve non-freezing fluids and heat
exchangers.
See, for
details:
Types of solar water
heating systems
Productivity of Solar Domestic Hot Water Systems
Simple residential solar hot water systems available today can
cut natural gas usage for at least 50%. This percentage can be
much higher and attain the 100% (“zero energy buildings) when
combined with energy efficiency measures.
The price of Solar Domestic Hot Water Systems
Residential solar hot water systems are cheaper than solar
PV systems. In today's USA they around
$2,500-$4,000 per home, for a production of about
80 to 100 gallons of hot water per day (a
PV system for production of electricity may cost 4 or 5 times
more).
Technologies of Solar Domestic Hot Water Systems
There are three main technologies:
1) Flat Plate Collectors, mainly used in pool water heating
systems;
2) Evacuated tubes, based on series of glass heat tubes;
3) Integral collector-storage or
batch systems (these
systems are unsuitable in freezing cold climates and involve
black tanks or tubes in an insulated-glazed box where the water
is heated, before continuing on to the conventional backup water
heater).
How to install Solar Domestic Hot Water Systems
Typical solar collectors require a flat mounting area of around
3 m2 for each collector. Most installations require one to two
solar collectors.
For maximum efficiency, solar panels should be mounted on a
south facing roof (in the north hemisphere) or on a north south
roof (in southern hemisphere countries) at an around 30° angle
with the horizontal. They also should be mounted away from
shadows (from trees, surrounding buildings, or other
constructions).
The correct
installation of solar domestic hot water depends on factors as
solar resources, safety, climate or local requirements and it's
best to have a qualified contractor install the system.
Retrofitted systems
Most solar water heaters can be retrofitted to your
existing water heater systems.
Maintenance of Solar Domestic Hot Water Systems
Passive and simple systems requires very little maintenance
(every 3–5 years, in some cases). For active systems, the needs
of maintenance are very similar to the conventional systems,
with minimal costs. Just consult the system's owner's manual and
discuss the issue with the installer.
System sizes
Optimum size for a domestic solar water heater depends on
the water use, which depends on the number of occupants, of
appliances such as dishwashers, washing machines, etc.
Impact on environment
California Energy Commission
studies show that the installing of solar hot water systems on a
million homes and businesses over the next ten years would
reduce natural gas demand by nearly 10% of California’s total
residential natural gas demand for water heating. Studies of the
University of Wisconsin-Madison
show that installing 75% of U.S. buildings with solar
technologies would cut more than 300 million tons of CO2
pollution each year.
See also:
Basics of
solar systems
Solar Electricity: Photovoltaic PV Systems
Pros and Cons of Solar
Energy Panels
Costs and payback of
Solar Energy
Sizing Solar Systems
Solar Systems Orientation and
Location
Solar Panels Technology
Quotes and the
buying process
Market and Prices of Solar Hot
Water Systems
Market and Prices of Solar PV
Electricity
Manufacturers of Solar
Power Systems
What to ask to installers and
suppliers
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