Solar Thermal Hot Water - The power of the Sun

There’s no better way to heat the hot water for your home than heating it for free!

Solar thermal is a fantastic technology and can provide up to 60% of a households hot water requirements and can be effective on cloudy days.

Solar thermal is best suited for properties with a roof that faces to the south, or south west to maximise the exposure of the panels to the sun throughout the course of a day but even if you don’t have a south facing roof there are ways that the panels can be installed to overcome these issues such as A frames or split systems where panels are installed to both front and back of the property.

The inside job.

Once the panels have been installed all the work is then on the inside of the property where the pipework needs to be connected to the pump station which is then connected to a twin coil hot water cylinder which is usually of the unvented type. A twin coil cylinder is simply as it’s read a cylinder that has two coils, one coil is connect to the solar panels and the other is connected to the heating system. The solar panels have their own controls which monitor the temperature of both cylinder and the panels and only provide heat if the cylinder water temperature is lower that its target temperature usually 60c, and also if there’s enough energy being generated by the panels to raise the temperature of the cylinder water. For example if the temperature of the panels is 40c and the water inside the cylinder is at 45c the system knows that there’s not enough energy to raise the temperature of the water to 60c and so 15c difference will have to be made up from the heating systems boiler.


Here are a few pictures from an installation we carried out in 2019. We converted a conventional gravity fed heating and hot water system to a sealed Worcester Bosch solar hot water system which included a 30 Cdi system boiler, 210 litre Worcester twin coil unvented cylinder, Worcester TDS100 solar controller and a Worcester AGS2 solar pump station.

Worcester Greenskies

Having installed a lot of Worcester products there’s no surprise that we recommend the Worcester Greenskies system, it just make sense that if a manufacturer can provide a full system solution to use the same products throughout. We know that the Worcester products are quality, reliable and robust along with great after sales and technical support.

In the Video below Roger Bisby explains a little more about the Worcester Bosch system.



We don’t just install solar thermal systems we maintain them too!

As with any heat source within a property it’s vital that they get looked after to avoid any premature failure which could result in high repair costs. A solar thermal system uses a substance called glycol as the heat transfer fluid to prevent frost damage during the colder winter months. Over time the glycol will degrade and it’s ability to stop freezing will deteriorate, at the same time if the system is not being used in the most efficient manner or turned off ┬áthe glycol can also bake within the panels and turn into a sticky substance which is unable to be circulated around the system.

It’s vital that the quality of the glycol is monitored and replaced as soon as it starts to show signs of degradation, if it’s ignored it will almost certainly render the whole system useless and will more than likely need to be replaced. However we have come across systems that can be restored by adding chemical cleaners via solar pumping machine and circulated around the system to break down the glycol and restoring the system back to a reasonably working order.

Below are a few images of maintenance carried out on a solar thermal system in Penarth.


We cover Blackwood, Abergavenny, Pontypool, Cwmbran, Newport, Cardiff, Usk, Crickhowell, Brecon, and anywhere in between!