In the North, in addition to the cold weather, in the winter, there is little sunlight, so the solar water heater does not work well. Even many families at times can not use the bottle because the water is too cold, not unlike the water flowing from the tap.
To remedy this situation, 100% of households currently using solar water heaters have installed hot and cold water heaters. Depending on the conditions, they can be installed in consumption places such as toilets, kitchens ...
Accordingly, the experts agreed with the installation of an auxiliary heating device directly (electric heater )to the solar water heater.
When it's overcast, the solar heater can't heat the water. At this point, the resistor will become an indirect water heater - like a normal electric water heater. Note, you only need power resistance when solar radiation is not enough to heat up and you still want to use hot water.If you use this device, in the winter, you can still save 70% on electricity compared to using an electric heater .
It is not difficult to install this auxiliary device. You can now buy it at stores that sell solar water heaters or electrical appliances. The solar water heater itself has been designed to fit in with this device.
Accordingly, when installing, workers just need to open the lid on the insulation tank, put the resistance bar in and set the mode, pull the power source to suit the level of use.
Active mode and temperature settings
To ensure there is hot water in the absence of solar radiation, the simplest and cheapest way is to install a resistance bar for solar water heaters. To reduce the heat loss of the bottle, it is necessary to set a low resistance temperature of about 40 to 50oC. Hot water pipes from pots to households such as bathrooms, kitchens should be insulated carefully.
In addition, it is necessary to attach anti-shock safety devices. For added safety, the resistor must be disconnected before using hot water.
Similarly, another solution is to use solar energy in combination with a heat pump. That is, install a hot water heater in series with the solar water heater. When there is no solar energy, the heat pump is used to boil water. Heat pumps are more energy efficient (can save up to 60-70% of the electricity) but the initial investment is very expensive.
Experts concur, because the solar water heater is well insulated, so when using the resistance bar, it will help keep the hot water for a long time like a heater. The heating of the solar water heater is equal to that of an on-site heater. Therefore, do not be afraid to waste hot water when not in use. Particularly in the days when the sunlight is weak, the water temperature is inherently warm, now heating with the resistance bar will quickly heat, saving more electricity.