Fothermo 300-liter photovoltaic boiler

The Fothermo 300L Water Heater (MPN: PVB-300) produces cost-effective hot water using solar energy. This freestanding photovoltaic water heater provides a solution for hot water and can be easily connected to existing heating systems. The easy integration of the solar modules ensures a reliable hot water supply in a matter of seconds. It features no fewer than 3 independently operating photovoltaic heating elements. Each of these heating elements is individually powered by an MPP tracker. Each heating element can handle an impressive photovoltaic output of up to 2000 Wp.

Product Highlights

• 300-Liter Photovoltaic Hot Water Boiler
• Hot water for the sink, shower, or kitchen
• No connection to the power grid required
• No professional installation required
• Optional reheating via the heating system is possible
• Integrated heat exchanger
• Three independently operating PV heating elements
• 3 MPP trackers
• Simple PV connection
• Plug-and-play

The boilers operate at a power output of up to 1,800 W to heat the water. To ensure you never have to go without hot water—even on cloudy days—a total photovoltaic capacity of up to 6 kWp can be connected. If desired, there is also the option of supplemental heating via your existing heating system. Installation is straightforward, similar to that of conventional floor-standing storage water heaters. A vacuum relief valve and a check valve are also included in the package to ensure maximum safety.

No registration required: Since no electricity is fed directly into the grid, there is no obligation to register the photovoltaic system.
Heat Exchanger: You have the option to connect an existing heating system to provide additional water heating on days with limited sunlight.
Easy installation: The photovoltaic modules are connected to the water heater. Due to the low voltage and the simple plug-and-play principle, no assistance from an electrician is required during installation. Energy is transferred via electrical cables, unlike complex solar thermal systems that rely on piping.
Payback period: This is typically 3–5 years. After that, you’ll essentially be using your hot water for free.

Technical Specifications

• Volume: 300 liters
• Max. heat loss: 50.2 W
• Nominal pressure: 0.8 MPa
• Dimensions: 1605 x 670 x 760 mm
• Weight: 88 kg

Heat exchanger

• Nominal pressure: 1 MPa
• Max. temperature of the heating fluid: 110°C
• Max. temperature in the tank heated by the heat exchanger: 95°C
• Surface area: 1.12 m²
• Volume: 5.4 liters
• Continuous output according to DIN 4708: 35 kW
• Flow rate according to DIN 4708: 14 L/min
• Output according to EN 12897: 19.3 kW
• Heating time according to EN 12897: 39.4 min
• Pressure drop: 50 mbar

Photovoltaic heating

• Max. current draw: 16 A
• Rated electrical power: 1,800 W
• Max. connected power: 6,000 Wp
• Max. connected power per MPPT: 2000 Wp
• Max. water temperature: 65°C
• Max. open-circuit voltage: 50 V

Caution: The open-circuit voltage of the solar modules must not exceed 50V. When using multiple modules, they must be connected in parallel, not in series!

Package contents:

1x Fothermo 300L PV water heater
1x Check & Pressure Relief Valve