Energy storage is a fundamental requirement as we transition to renewable energy sources. Thermal energy storage is very effective, has high energy density and very low cost.
Solar PV and Thermal Energy Storage
Q&A with Mitch Hodges, Co-Founder & CEO | GreenPWR
Tell us about yourself and your role with GreenPWR.
Mitch Hodges- cofounder and CEO of GreenPWR. I am an electrical engineer with prior experience in mobile devices, IoT devices, smart lighting systems, and now into renewable energy devices.
GreenPWR started after I left my prior job in the mobile device space and studied for my masters in sustainable and renewable energy at the University of Nottingham. During my studies, I met the Hockerton Housing Project team (currently one of our cofounders in GreenPWR) and began work on a renewable energy storage system using PV for hot water. After that short project timeframe of 3 months, we had a working prototype. It was clear this was a feasible product for the market and modernised renewable hot water production, so we proceeded forward with bringing this to market with our 2 additional cofounders.
Where are we with Solar Thermal? How has technology advanced hot water production via PV over the last few years.
Innovations in solar thermal systems have reached a plateau. Simple thermosyphon systems with a tank on the roof exist, although the installation practicality is limited. Any temperate climate where freezing is possible will require the more complex closed loop system which has plumbing from the roof through the home, a specialized hot water tank with a heat exchanger, and a pump. These components have possible failure cases which are catastrophic to the solar thermal system. With any plumbing system, leaks are possible. Overheating is another concern in the event there is little water usage or if a pump were to fail.
PV has seen decreasing prices over the years. This has allowed systems based on PV to become more viable. Some companies have begun to create products to support this special use case, though this is still in its infancy.
What are the benefits of generating hot water via PV?
Hot water via PV brings several practical advantages over traditional solar thermal systems. Installation is much simpler. Wiring is used to transfer energy from the PV array to the inverter instead of a thermal transfer fluid via plumbing.
With the PV system there is no risk to overheating as the energy is collected via electricity. The overall system is optimized for installation by using off-the-shelf components. An existing immersion heater electric water tank, PV panels, a mixing value, a rapid shutdown device and a SunHopper-D are the required items. This increases installation speed dramatically and keeps costs low.
PV panels have decreased in cost over the years. This allows the SunHopper-D system to beat the cost of solar thermal systems and be much simpler to install, making this a modernized method of generating domestic hot water via solar.
Additional rooftop space is indeed required when using PV instead of solar thermal as the collector efficiency is lower. Although this is the case, the benefits of the system still outweigh this downside.