Wall-mounted water heaters

LX ACDC/M (M+K and KW) water heaters represent a new technical solution of water heating using environmentally clean energy sources. Water heating uses the energy of the sun that, by means of photovoltaic cells, produces direct electric current that heats the water in the tank. Original solution is the connection to photovoltaic panels in which no energy losses are generated and therefore the device works very effectively whilst providing thermal protection and safe control of the entire system.

Simplicity and variability of locating the photovoltaic panels, their maintenance-free operation and easy connection to a water reservoir via a thin electrical cable gives practically unlimited possibilities for use of the appliance in both family and prefabricated houses, as well as in industrial buildings. 

Globally, it is a production of electricity from renewable energy resources.

Using photovoltaic panels for water heating is environmentally friendly electricity generation, which is in its entirety consumed directly by the manufacturer. No permits are required for the connection and no additional peripherals have to be purchased. So far, it is the most efficient and lossless utilization of electricity from photovoltaic panels.

Heating possibilities

The intensity of sunlight affects the weather and the seasons and so the sun is here, in local conditions, am unstable power source. Hybrid water heaters can warm water by sunshine or by a combination of sun and permanent sources of energy (gas, electricity supply). LX ACDC water heaters are designed for preheating and eating of water.

Water preheating 

For water preheating, water heaters are connected before gas or electric boiler with tank or flow water heating or a heat pump to a source of cold water (Fig. 1).

Preheated hot water from the PV panels flows directly into a tank, heat exchanger in a gas or electric boiler and, when sufficiently hot, gas or electricity is not withdrawn, which means large energy savings. If water is not sufficiently heated with the energy from photovoltaic panels, it is finally heated by the water heater. Heating water itself consumes considerably less energy than heating cold water. Such connection of LX ACDC water heaters guarantees hot water even if the weather is unfavourable for longer periods, while also saving considerable funds. When heaters are used to preheat water for a heat pump, water preheated to a maximum temperature limit of the heat pump flows into the heat pump tank instead of cold water.

That connection leads to extended life of the heat pump by almost 30 %.

Connecting of the LX ACDC water heater before a gas boiler allows heating water even when gas supply fails or is limited. In that case water is heated by sun or, if the weather is bad, the second “backup” coil in the water heater can be activated by switching on the second thermostat. The backup coil is connected to electricity grid (AC 230 V). Its activation makes the LX ACDC heaters become conventional electric water heaters and, together with the power supply from photovoltaic panels, fully heat water even without gas supply.

Water heating

LX ACDC/M water heaters can be used as independent electric water heaters. They operate on the principle of two separate electrical circuits (Fig. 2). The first is connected to the power grid (AC 230 V) and the other is connected to environmentally clean electric power from photovoltaic panels. Both circuits can operate simultaneously or each separately.

Connection to the power supply from the grid guarantees heating of water during prolonged bad weather. The desired water temperature (e.g. 45°C) is set by the thermostat.  Once the preset temperature is reached,  the electricity supply from the grid (AC 230 V) shuts off automatically and the water in the heater is further heated with environmentally clean electrical energy from photovoltaic panels (heating up to max. temperature of 75 °C).

That new manner of water heating leads to significant savings in electrical energy drawn from the grid with an accompanying considerable savings of financial resources. LX ACDC water heaters can also be used in the night current regime (low tariff). In this variant, cheap night time power source heats water at night, and ecologically produced power from photovoltaic panels during the day.

Types of LX ACDC/M (M+K & KW) water heaters

All types of LX ACDC/M, M+K & M+KW water heaters have an in-built universal direct-current spiral from the panels. Universal coil can be connected to a photovoltaic source of 1.0 kW (120 V DC), 1.5 kW (180 V DC) or 2.0 kW (240 V DC).

The system includes a 1-2 kWa LXDC SET that is installed on the wall next to the heater and provides both disconnecting or diverting the energy of panels, the safety of the system and even the mode of operation of the photovoltaic installation with respect to the connection or non-connection to a public distribution system which means whether the system is operated ON/OFF grid.

As a complement to the system for maximum energy gain our configuration can be enriched with LXDC POWER BOX which is an electrical device designed for power adjustment of photovoltaic panels to constant resistive load – a DC heating element. The device operates on the basis of a MPP (Maximum Power Point Tracking) feature known in photovoltaics. In other words, LXDC Power Box is an equivalent load that is adjusted so that under any sun conditions the maximum capacity of the DC heating element was achieved. For wall-mounted heater variants the variant suitable is LXDC POWER BOX 1-2 kW.

Generated electricity from photovoltaic panels can also be accumulated using a system of two water tanks (Fig. 3). 3).

Electricity from panels preferably heats the water in the first water tank that is intended for normal consumption of household hot water. When the first tank is heated, electricity from solar panels redirects automatically to heating the heat water in the second tank which is connected to a dishwasher and, via a mixing valve, also to a washing machine. After switching on the dishwasher or the washing machine, electricity is not drawn from the grid for water heating, since hot water flows into the dishwasher and washing machine instead of cold water. In that case, the second tank replaces the function of an electric battery. The effect is the same – minimised consumption of electricity from the grid. The second tank also provides preheating the water for the first tank. In such connection a DC/AC converter is not required to produce electricity to the grid, or charge controller, battery or inverter. 

No generated electricity from PV modules gets into the distribution grid, and therefore there is no need for approvals and permissions from the distribution company.

The entire ecologically produced electricity from PV panels is consumed in the home, thereby significantly saving money at home for uncollected electricity from the grid.

All hybrid water heaters of the M, M + K & KW model series shut off after heating up the water to a preset temperature of the water and automatically reroute power to the converter (Fig. 4), where direct current (DC) changes to alternating current (AC). Ecologically produced electricity is preferably consumed within the internal electricity grid and, if the production covers the immediate consumption in the house, no electricity is drawn from the public grid. The electricity produced in the above described manner brings considerable financial resources to the owner for the electricity saved from the public grid. Here, it is necessary to change the position of the LXDC POWER BOX device installation so as not to affect the parameters for MPPT converters.

The use of a M+K (KW) series water heater not only allows 100% utilization of electricity generated from the photovoltaic panels but allows the use of the maximum permitted source of photovoltaic panels even for smaller tank volumes. For larger hot water withdrawal and subsequent reduction of its temperature in the water heater the electrical energy from photovoltaic panels will be automatically transferred from the converter to the water heater. The converter switches off. After heating the water the process repeats automatically. The resulting effect of using the LX ACDC water heater is not only hot water, but also own production of electricity for household that can be used for example to power air conditioning or heating. All that through an environmentally clean power source. Energy surplus from the water heater can be redirected to heat up another water heater (Fig. 5).

LX ACDC series water heaters provide mechanical disconnection of DC current for disconnecting the converter (DC / AC) from the public grid.

LX ACDC/M+K hybrid water heaters (Fig. 6) can be, besides heating with DC and AC current, connected an external source of heat (fireplaces, ovens, boilers and the like.).Using an in-built pipe system (exchanger) in the heater, the heat is given to water heater. LX ACDC/M+K hybrid heater can be connected to an external hot water source with max. temperature of 100 °C and pressure of 1 MPa.

LX ACDC/M+KW hybrid water heaters

The M+KW model series is only produced in 200 l version and has two 100-litre temperature section.

Connection to gas or electric boilers as hot water accumulation tank is designed for: underfloor heating in passive and low-energy buildings as environmentally friendly electric boiler The M + KW model for hot water production is divided into two sections (Fig. 7):

Water in the lower part (B) is heated and, according to the temperature, rises to the upper section (A) of the tank where the water is heated by gas or electric boiler to a desired temperature. If the water temperature in the bottom section (B) reaches the temperature of the upper section (A), the photovoltaic source heats the entire 200 l tank (A + B), up to the maximum temperature of 75 °C (Fig. 7).

Heating water by the M+KW model represents a very efficient use of ecologically produced electricity from the sun, which leads to significant savings of gas or electricity and significantly prolongs the life of gas and electric boilers.

The M+KW model can also be utilized as an environment friendly boiler for floor (water) heating in low-energy and passive homes.

After the end of the heating season, ecologically generated electricity from photovoltaic panels can be automatically redirected from LX ADCD/M+KW to inverter for producing AC power to be used in homes, or for direct heating of water by means of another hybrid heater LX ACD/M+K. it can also be diverted to charge batteries.