ThermaTwin - Solar Hot Water, PV Powered

Originally marketed under the 'Solar Twin' banner, the ThermaTwin solar thermal panel has been in production for over 13 years, and has over 3,000 successful installs.

The secret to ThermaTwin's success is its simplicity, reliability and ease of installation.

Using a unique freeze tolerant, flexible and hygienically approved pipe inside the flat plate solar collector, the ThermaTwin panel takes the drinkable water from the domestic tank and returns it directly back to it as hot water, at up to 80°C.

At a stroke, ThermaTwin eliminates the hidden losses in more complicated solar thermal systems that have glycol (better known as anti freeze) which is 30% worse than pure water for absorbing heat and requires regular level checks and maintenance to maintain performance. By feeding the tank direct, ThermaTwin usually does not need a heat exchanger which again underpins the systems surprising performance and efficacy that simple output temperature graphs cannot really demonstrate.

In addition, the elimination of Glycol from the system makes the water less viscous and easier to pump round; so much so that a small low voltage variable speed DC pump is adequate. A small 'onboard' solar PV panel is thus easily able to provide enough power to run the pump and controls. The Solar PV panel again provides a performance gain not considered when comparing simple output figures with more expensive and complicated flat plate or evacuated tubes that use mains powered pumps and controls.

This makes the entire ThermaTwin system 'off-grid' as it uses the power of the sun to both heat the water and power the pump – something no other system can do. The patented design is thus ideal for properties looking to come off oil or LPG without increasing their electric demand, and is eligible under the RHI schemes.

Nothing is as Reliable as ThermaTwin

ThermaTwin Solar Panel

Similarly ThermaTwin can be retrofitted onto the 1,000,000's of UK properties that have a perfectly serviceable vented cylinder with practically no modification to the pipe work, and without the need to upgrade to an expensive twin coil cylinder – which would also require an annual inspection to maintain a landlord safety certificate.

Consider ThermaTwin’s unique benefits:

  • PV Powered pump and controls means genuine zero running costs
  • No glycol means no maintenance or level checks
  • Simple controls ensures long life reliability
  • Direct to tank design means minimal disruption & costs to install
  • Lightweight (<30kg empty) means easier install and minimal roof loading
  • Eligible for RHI projects


DiscreteHeat Company Limited
1 Victoria Works Industrial Estate
Coal Pit Lane, Atherton
Manchester, M46 0FY

01942 88 00 60
01942 66 51 04

VAT# 884427392
Company Reg# 5594330