The hot water needs for domestic properties can vary greatly depending on the occupancy. Tweed Renewables Ltd are experienced solar heating installers and can perform an on site survey to determine what volume of hot water is required daily and then tailor a solar water heating system to suit. This will include solar panels, heat transfer pipework, hot water cylinder, pump station and control unit.

The installation of a solar water heating system is an important step for a home owner to take. You will be taking control of the money you spend each year on your hot water heating bill. Either you invest in a solar water heating system that gives you energy security (increasing fuel costs will have less effect on your monthly bills) or you continue to give money away to a utility company for an ever increasing service. The installation of a solar water heating system will typically take three to four days with minimum disruption to your current services.

Solar water heating systems require very little maintenance. An annual check of the anti-freeze based heat transfer fluid can be undertaken by the home owner. It is good practice to have the anti-freeze changed every five years.
Tweed Renewables Ltd are BPEC approved Solar Water Heating installers.

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 atmosphere. The solar irradiation falls on the collector and heats the fluid within. It is this heat that is transferred to the tank.

df100A Kingspan Thermomax DF100 evacuated tube panel installed in Peebles


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.


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.



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.