Public Funding for Soltropy Limited

Our project will help reduce operational costs associated with space and water heating and will help decarbonise heat. Our proposal is to integrate our novel solar thermal innovation with air source heat pumps to provide space and water heating. Our innovation allows our solar thermal panels to freeze without damage eliminating the requirement for antifreeze. This means we can use water as the heat exchange fluid and design larger systems without being size constrained. Our system can overheat safely allowing larger arrays without the corresponding large water storage required to prevent overheating. Existing systems that use antifreeze are sized so that they never overheat as the antifreeze degrades and requires replacement. This means that the system is sized for the sunniest day of the year and matched with the available water storage and is undersized for most of the year. In the UK a 4.5 sqm evacuated tube collector (30 evacuated tubes) would require around 250 litres of water to prevent it overheating in summer. As our system uses water as the heat exchange fluid we can allow it to overheat, have larger arrays and get useful energy throughout the year that can contribute to space heating when it is needed in the cooler months. We have proven this innovation with 20 sqm of evacuated tube collector but with only 200 litre of water storage on a dairy farm. If this was an antifreeze type system it would require 1,200 litres of water storage to prevent overheating in summer. This would be costly and impractical to implement in most cases.

This project will combine a Soltropy freeze tolerant solar thermal system with heat storage capability. This will make the overall system more effective and expand the use of solar thermal by making the it more cost effective. The project's main focus is to - 1. Reduce the cost of the system for installations where space heating is required. 2. Reduce the cost of the system for installations where there is no existing hot water tank. 3. Increase the performance of the system.

The aim of the project is to integrate Soltropy’s patented freeze tolerance solution, developed for vacuum tube solar thermal collectors, with AES Ltd’s (AES Solar) flat plate solar thermal collectors. This will help to significantly reduce the installed cost of their solar thermal systems. Most solar thermal systems in the UK do not run water directly through the collector panels as it can cause freeze damage. Instead they run an antifreeze fluid through the collector which means that when a new solar thermal system is installed a perfectly good tank is replaced by a new hot water tank with a heat exchanger. This can double the price of the installed system due to the new tank and additional labour costs. A new tank is not required with Soltropy’s solution which allows water to be used directly in the system. It works by using a compressible tube inside the copper piping which takes up the expanded volume of the water if/when it freezes. The cost savings made from not needing a new hot water cylinder and from the reduced installation time will lead to a steep reduction in the installed cost of solar thermal systems

Most solar thermal systems in Northern Europe have a separate antifreeze filled loop for protection against freezing and require a new tank fitted with a heat exchanger. When retrofitting to existing homes this means that a perfectly good tank (usually copper) needs to be replaced. We have developed an innovative solution that allows a domestic water supply to be heated directly, without the secondary fluid cycle. This increases the efficiency of the system and reduces capital and installation costs. Our solution allows the system to freeze but cause no system damage by using a compressible closed cell silicone sponge tube within an outer copper pipe. When it freezes the compressible tube takes up the expansion due to the ice and prevents pressure build up and damage to the system. This study will optimise the control strategies.

Most solar thermal systems in Northern Europe have a separate antifreeze filled loop for protection against freezing and require a new tank fitted with a heat exchanger. When retrofitting to existing homes this means that a perfectly good tank (usually copper) needs to be replaced. We have developed an innovative solution that allows a domestic water supply to be heated directly, without the secondary fluid cycle. This increases the efficiency of the system and reduces capital and installation costs. Our solution allows the system to freeze but cause no system damage by using a compressible closed cell silicone sponge tube within an outer copper pipe. When it freezes the compressible tube takes up the expansion due to the ice and prevents pressure build up and damage to the system. This study will determine the optimum specification of the silicone sponge tube by trialling various specifications of tubes and sizes in a real world situation as well as freeze tests.

Freeze tolerant solar thermal system using new material advances, resulting in more efficient system at lower cost.