German startup Nexol Photovolthermic AG has unveiled a 1,500 W water heater that can use photovoltaic energy without an additional converter.
“The system can be ordered in three configurations starting from the third quarter of this year,” the company's co-founder, Michael Lau, told pv magazine.
All of the systems include a smart controller, known as the Nexol-Energy-Controller. It can work with either DC and AC power and decides autonomously if grid electricity or photovoltaics is used, with the latter being always preferred. Users can choose between one or two heating rods: the NEX-R1 and the NEX-R2.
“To install these retrofit sets, an existing tank needs 1 ½ threaded sleeves at a suitable height,” Lau explained. “We also offer a 120l tank for the two-rod configuration, which is dubbed NEX-R2x120, and the plug and play principle makes installation very easy.”
If two heating rods are integrated, they enable zone heating of the tank inlayers, said Lau. “The application of heating zones allows reducing significantly grid power consumption,” he added.
The function principle of the two-zone heating is described by the company as simple. At first, the upper zone of the storage tank near the hot water outlet is heated to 60 C. This enables faster hot water withdrawal, with PV prioritized as an operating source.
In the case of low solar radiation, the intelligent system reheats the upper zone of the water through the network. Thus, as little grid power as possible is used to provide hot water since only the upper zone needs to be heated for this purpose. As soon as the upper zone has reached its target temperature, the system switches to the lower heating element and thus heats the entire storage tank. “The energy generated by the PV panel is stored in the water,” Lau said.
The company said the standard PV installation that should be coupled to the water heater is an array with four 375 W panels. “Other configurations are possible, even with more power,” Lau added. “All you have to check is the maximum input voltage of 500 V.”
The product was developed and fabricated by Nexol in Germany. It will be available from an entry price of €799 ($845) and is purportedly suitable for the European markets, as well as other regions.
“For example, while the NEX-R2x120 is well suited to replace gas boilers in households around the Mediterranean, our R1 and R2 retrofit sets are also well suited for households in the DACH region to be integrated into existing systems and thus reduce costs,” Lau concluded.
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