When UK-based SolarHotty approached Tellumat in 2015 with a concept for a product that would reduce the cost of electricity used in domestic water heating, it was a vote for a world-class technology partner compliant and experienced in electronic manufacturing, to stringent international standards, and who could ensure an unbroken global supply to SolarHotty’s customers.

What the renewable energy pioneer didn’t know at the time was just how crucial Tellumat’s end-to-end portfolio of services – including design, testing and industrialisation – would be to the success of the venture and this recently led to SolarHotty appointing Tellumat as their sole global manufacturer for the product in June 2017. 

Market need

Electric-powered hot water cylinders are among the world’s highest electricity consuming devices. But while solar water heating solutions are growing in popularity, the cost of their installation and maintenance puts these systems out of reach of many home owners and furthermore, without supplementary electrical heating, the requirement for “on demand” hot water cannot be guaranteed.

Hence, SolarHotty conceptualised an alternative water heating solution powered by both photovoltaic (PV or solar) cells and mains electrical heating. The brilliance of the SolarHotty concept is that it not only significantly reduces electricity used in providing hot water, but it works with readily available, off-the-shelf and proven Alternating Current (AC) powered electrical hot water cylinders.

Tellumat reviewed the concept and proposed a design to meet the product’s requirements. Several technical challenges had to be overcome during the systems engineering phase, but once the design was derisked, Tellumat produced a number of prototype systems and performed comprehensive lab and field tests to prove all aspects of the design.

Currently awaiting SABS and UL (US) electrical safety certification, the fully-industrialised device will be manufactured exclusively by Tellumat to meet the anticipated significant global demand.

Technology solution

The SolarHotty is a cost-effective and intelligent electronic device that converts standard homeowners’ hot water cylinders into hybrid green water heaters – drawing directly on solar-delivered Direct Current (DC) power with backup access to grid-delivered Alternating Current (AC) power.

The device achieves the feat of coupling solar power with any electrical resistive heating element and an existing AC thermostat, without the use of costly inverters or battery systems, meaning it doesn’t require any change to a newly installed or existing hot water cylinder.

Using solar by default, it switches over to grid power when necessary, ensuring users always have hot water, but minimises the consumption and cost of mains electricity.


Whether fitted to a new or existing hot water cylinder installation, the SolarHotty product ensures homeowners have hot water “on demand” but with a significant reduction in their electricity bills. Exceedingly simple to install, the SolarHotty does not impact on existing plumbing, is easily integrated into existing infrastructure and does not negatively impact on the hot water cylinder manufacturer warranty.

As a green energy solution, it has exciting potential to significantly reduce the global consumption of electricity from non-renewable energy sources, with a rapid pay-back and ongoing financial benefits to the consumer.

To find out more, please visit www.solarhotty.com