US homeowners Laura and Gil have been living off-grid since 2000. Their PV-powered home features a fossil-fuel-free outdoor kitchen with a system for on-demand running hot water provided by a Sunamp thermal battery. The heat battery uses excess electricity generated for free by photovoltaic panels. The installation, which required minimal plumbing, took just 15 minutes, and has reduced their use of firewood for domestic hot water by 20% annually.
Passionate about climate change, the New Hampshire homeowners wanted instant hot water outdoors for washing dishes, cleaning up after cooking in their outdoor kitchen and to be able to have hot showers without wasting water and energy. They were keen to take advantage of surplus PV-generated electricity and store that energy efficiently to provide hot water to suit their needs. The hot water solution had to avoid 75 feet of additional plumbing as well as circumvent freeze-thaw issues, vermin problems and pipes and penetrations which are typical in a super-insulated home. An under-sink on-demand water heating system did not provide enough hot water.
The Sunamp heat battery is up to 4x smaller than an equivalent hot water tank, which means that it fits snugly into a small cabinet. It is charged using surplus PV-generated electricity which would otherwise have been wasted, and, unlike a classic solar hot water system or solar hot water panels, its extremely low heat losses make it very energy efficient. The heat battery can be recharged with a switch when required, similar to time-of-use. As the weather cools and the outdoor kitchen is no longer used, it can easily be wheeled indoors and stored, ready to reinstall when the warm weather returns.
The Sunamp heat battery has many benefits for outdoor kitchens and off-grid living in general. It’s easy to install, space-saving, requires no maintenance and stores hot water safely for long periods with minimal heat losses. Laura and Gil’s carbon footprint has been reduced by approximately 2.5 tons CO2/year.
The energy source for the Sunamp heat battery is roof and pole-mounted photovoltaics, which provide electricity to charge the battery via two RELiON LiFePO4 batteries and Schneider inverters. The heating capacity and storage capacity of the battery are 3.5kWh, and the supply temperature varies between 100°F and 130°F, tempered with a mixing valve, recharged as needed.
“The Sunamp heat battery is an elegant, efficient, simple-to-use solution to a complex challenge for us. We are excited about soon replacing our existing, inefficient, clunky, primary home-heat/DHW storage system with Sunamp. That’ll further reduce the amount of wood we handle and burn each year.”