Turkish heating solutions provider Water Heating Systems (WHS) has presented this week its DC Sunboil range of photovoltaic-powered water heating systems, targeting residential and small commercial applications at the SolarEX Istanbul trade show.
The product line is designed to operate without an inverter, directly converting solar power into heat via DC electricity. According to the company, this approach reduces both upfront investment and system complexity, while improving reliability in off-grid environments.
“The system works with four photovoltaic panels connected in parallel and runs on an extra-low voltage level, which enhances safety,” Ahmed Kılınç, R&D engineer at WHS, told pv magazine. “Typically, the system uses standard 400 W PV panels, resulting in a total installed capacity of around 1.6 kW. The system is flexible, allowing users to scale by adding more panels if needed. It is also compatible with conventional PV panels, provided they meet the required voltage level below 50 V for safe operation.”
The system connects directly to photovoltaic modules via plug-and-play connections. Each unit integrates maximum power point tracking (MPPT), enabling optimized solar energy harvesting without requiring external electronics. The system is also capable of hybrid operation, with an integrated electric heating element ensuring continuous hot water supply during low irradiance or nighttime conditions.
The DC Sunboil series is offered in five tank sizes ranging from 120 liters to 500 liters, designed to meet varying household and small commercial hot water demands. The smallest model in the range is the 120 L (WHS-120-HBB), designed for 2 to 4 users, while the largest is the 500 L (WHS-500-HBB), which can serve between 8 and 16 users. All variants operate at a maximum working pressure of 0.6 MPa and are equipped with two MPPT trackers.
In terms of electrical configuration, the systems support up to 1,200 W of PV DC input power and include an external AC backup heating element rated at up to 2,000 W. The recommended photovoltaic array size ranges from 1.6 kW to 2.4 kW, with each MPPT tracker handling between 800 W and 1,200 W. The maximum PV current per MPPT is 15.5 A, making the system compatible with typical low-voltage PV module setups.
“One of the key advantages of this system is its simplicity and efficiency,” said Kılınç. “Since it directly converts solar energy into heat, it avoids the energy losses associated with inverters and battery storage. In this sense, the water tank itself effectively acts as an energy storage unit.”
The device is primarily intended for domestic hot water production and is not used for electricity generation or grid feed-in. However, it does offer flexibility, as an AC backup option is available, allowing the system to operate during nighttime or cloudy conditions.
“The system can produce approximately 3 kWh of thermal energy per day on average, although actual performance depends on seasonal variations and sunlight availability. The water temperature is adjustable, typically ranging between 65 C and 85 C, which provides sufficient capacity for household needs,” Kılınç stated, noting that while the system itself does not incorporate battery storage, it is technically possible to integrate a battery through an external switching mechanism. However, this is not the primary design intention, as the system relies on thermal storage rather than electrical storage.
WHS is based in Adana and currently sells its products within the Turkish market. “However, we hope to expand our customer base outside Turkey,” Kılınç concluded.
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