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Solar PV For Hot Water


Solar photovoltaics (PV) can now do more than just provide cheap environmentally friendly electricity, it can now also provide the home with hot water. This type of Electrical Water Heater (ELWA) differs from traditional solar thermal systems as it uses an electrical heater directly installed within the hot water tank.

If you have solar PV or considering getting it you may not yet be aware of this clever technology that compliments solar PV and provides the extra benefit of providing hot water.

Solar PV on your home is continually working for all the daylight hours, even when you don’t require it. It is estimated we only use 30% of the solar energy we produce for our own use. Usually the excess energy is exported back to grid. If you were to redirect this unwanted power to heat the hot water tank, the money you would save far outweighs the money you receive from the grid. It would mean rather than using 30% of your free solar energy you could be using 89%. Your conventional heating bills whether it be gas or oil will be reduced and you will be reducing further your homes carbon footprint.

An alternative to this system is thermal solar, this is a completely different type of technology which requires a different sort of solar panel. This can take up space on your rooftop and effect the amount of solar PV you could potentially install. Solar thermal has much more components and pipework which could lead to potential issues or failures in the future.

The ELWA is simple, just a heating element wired directly into your homes existing electricity infrastructure, and it is a great system for retrofitting into your existing grid-connected PV system.

Advantages over

Solar Thermal

  • Due to the elimination of the pipes 90% of the copper isn’t required
  • No need for pumps, valves, expansion tanks, insulations, etc…
  • Photovoltaic heating even works with low solar irradiance
  • No lossy start-up procedures (clocking, loop warm-up)
  • Maintenance-free (frost protection)
  • No material fatigue during system downtime
  • Efficiency independent from system temperature
  • More efficient at lower ambient temperatures
  • Nearly loss-free energy transmission from the roof to the boiler
  • Mounting in the boiler/tank is uncomplicated, even when full.
  • Nearly no internal consumption (2W)
  • Grid feed-in of the energy surplus instead of stagnation.
  • Rapid price and technical development of photovoltaics.
  • ELWAs can be used decentral, thereby no distribution losses in multi-family houses. The solar energy is converted into heat right where it is needed!
PV water heater
Grid Connected


Linear power control 0 – 3.000W for maximum self-consumption
3 – 18 kW power for each PV-system
Sinusoidal current consumption (no thyristor), grid compliant
Independent from the inverter
3-phase electricity-meter included
Plug and play installation: no adjustment or programming required
Communication cable can be installed in normal AC cable channel
Hot-Water securing (Boost-Backup) included
Easy installation – perfect for retrofitting

Grid Connected and Battery compatible


AC ELWA-E uses energy that cannot be stored in the battery
Linear power control 0 – 3.000W for maximum self-consumption
The AC ELWA-E communicates via ethernet with the BMS
Sinusoidal current consumption (no thyristor), grid compliant
Hot-Water securing (Boost-Backup) included
Suitable for many battery and energy-management-systems

pv hot water
A simple but effective solution…


Sometimes the simple solutions are the best. A heating element placed in the hot water tank and wired from your solar PV takes away much of the pipework and potential leaking issues associated with the Solar thermal option. Utilise more of your solar energy, saving more money and reducing your reliance on the grid.

Why wait?