EcoSolar Energy Conscious Design Limited
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Maximising the benefit from solar hot
water
Following these recommendations will further enhance the benefit from your solar hot water system.
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Install low flow shower heads, taps, install flow restrictors and generally conserve water
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Heavy washing or hot water consumption maximised during the middle of the day
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Showers to be taken in the evening
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If showers are to be taken in the morning, you may need to utilise the electric booster
however this should be minimised
System control
System Control Overview
A well designed system will incorporate a level of control that maximises energy savings whilst
allowing the end user to manage the system, supply hot water on demand and minimises the risks
associated with legionella forming in the cylinder. The level of control is dependent upon the user
requirements and the type of system installed. In summary a solar water heating system should be
controlled as follows;
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If the solar systems is pumped, the solar heating pump is generally switched off and is only
switched on when the solar collector is warmer than the bottom of the cylinder, i.e. there is heat to
recover and the cylinder temperature is below its maximum temperature.
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The system will often have a backup heating system such as an electric immersion heater. To
maximise savings these backup heating systems should be left off during the day until the solar
system has heated the water as high as it can, then the backup heating can be switched on to top up
the water temperature to the desired temperature.
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The backup heating is used to control the risk of Legionella.
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Ecosolar contollers automate the solar water heating system. The most commonly installed
controllers are the EcoSolar ESR21-R3 and the UVR61. These are described below;
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ESR21-R3, a multi function controller which automates the solar water heating system.
Temperatures within the collector, the bottom of the cylinder and the top of the cylinder are
monitored and displayed on the clear LCD screen. The solar heating pump is turned on when the
collector is warmer than the bottom of the cylinder, i.e. there is heat to recover. It also has a defrost
function, turning on the pump to circulate water from the cylinder to the collector to raise the
collector temperature if the collector temperature has dropped to a point where there is a potential of
freezing. See also earlier section on frost control. There is also the capability for the controller to data
log the heat being recovered from the collector, this requires the optional flow meter to be installed.
