Operates on
a small
electric pump and can have the solar storage tank in
a more convenient location, thus retaining larger quantities for
hot water consumption.
An active system
is one where the exchange fluid is actively pumped from the
storage tank through the collectors and back into the tank.
When the sun heats up the solar collectors, it actuates an
electronic differential controller that sends the cooler water
up and meters the volume so that you always get a consistent
temperature of heated water coming back into the tank.
It delivers (140
to 180 Deg. F.) temperatures exceeding those needed for modern
household usage, therefore, sustaining more hot water for
morning showers by mixing the supply of cold water with much
higher temperature solar water inside the storage tank.
The active solar water heating system consists of a single or
multiple collectors on the roof, providing the heat energy that
is stored in a well-insulated tank. Heated water is then held
in the storage tank ready for use. The tank can be a modified
standard water heater, but it is usually larger and very well
insulated. There is a back-up element set to activate at 120
degrees for when we experience several cloudy days in a row.
The best-known
solar heating device is the flat-plate collector, which is
widely used for water heating in many parts of the world. The
flat-plate collector absorbs as much as possible of the incident
solar energy that falls upon it. Since the collector is
normally fixed in position, the plate is close to perpendicular
to the beam of sunlight (and therefore maximum absorption) for
only part of the time, and the level of energy received
therefore varies more strongly with time and season than does
the actual intensity of the solar radiation.
This
application is the most popular and will heat 80-95% of all
household hot water consumption.
