Tweed Renewables Ltd - Solar Water Heating

solar water heating installers based in the Scottish Borders

solar

The use of solar energy to heat water is a simple and effective way to save energy and money.
The principle is straight forward - use free energy from the sun to heat your hot water.

Solar Panel

The solar panel is positioned on the roof of the building or alternatively can be sited on frames that can be fixed to external walls. The collectors have a selective surface which is good at absorbing energy but does not radiate much back to the atmospere. The solar irradiation falls on the collector and heats the fluid within. It is this heat that is transferred to the tank.

Controller

The controller monitors the temperatures of the solar water heating system. There are 2 sensors on a standard system.

Sensor1 - monitors the collector temperature
Sensor2 - monitors the temperature at the bottom of the tank

When sensor1 reads a temperature that is higher than that of sensor2 (normally 6 degrees centigrade) then the controller will turn on the pump and start transferring heat to the tank. In turn, if the temperature difference falls below a set value (normally 4 degrees centigrade) then the controller will turn off the pump.
Sensor2 also monitors the tank temperature. If this reaches a set value (normally 60 degrees centigrade) then the controller will turn off the pump.

Tank / Cylinder

The tank or cylinder is where the heat transfer from the sealed solar circuit to the domestic hot water takes place. There is an in-direct coil within the cylinder that heats the water within. The cylinder can be of the vented or un-vented type. Fig1shows a twin coil arrangement - one coil from the solar circuit and another from the auxiliary boiler circuit.

Boiler

Because unclouded solar irradiation cannot be relied upon at all times, solar water heating systems do not totally replace the more conventional means of providing hot water such as solid fuel, oil, gas or electricity. They are an addition to these systems, pre-heating the water and therefore reducing the energy that the conventional boiler needs to provide to meet the hot water requirement of the property.

Fig1.

Orientation and angle of inclination

In the Northern hemisphere solar collectors should nominally face south with an inclination of 35 degrees. However solar panels with aspects between 30 degrees East and 40 degrees West of South and inclination angles of 20 degrees to 45 degrees will loose only 10% of nominal performance. In cases like this the solar panels are sized up to compensate.

mob: 0775 690 9884
tel: 01721 724472