“Atmosfera” offers the ready solutions for photoelectric hot water supply, based on Czech DC/DC converter SOLAR KERBEROS. The photoelectric hot water supply systems differ from systems of solar thermal collectors with the larger efficiency during winter period, they are simpler in assembly and control, are not subject to overheating, as well as can provide with backup power supply.
The photoelectric hot water supply systems use the electric energy, produced by PV panels, for direct heating of water in hot water supply and heat supply system. The system is compatible with any storage tanks that allow installing a heating element and a temperature sensor.
The high efficiency in operation of system is achieved by application of PV modules in combination with MPPT technology. During winter period thanks to cooling of panels and increase in their production capacity, as well as absence of heat losses in the pipeline, the system demonstrates better performances in comparison with the solar thermal systems.
The photoelectric hot water supply system may operate in completely autonomous mode during daytime and heat the water only from energy of the sun. If there is an AC network and the production capacities of PV modules are insufficient, DC/DC converter will automatically turn on the additional heating of boiler from the external source.
The system will just turn off the electric power of the heating element from PV modules in order to protect against overheating, and the excessive electric energy may be used to charge accumulator batteries or to heat an additional boiler.
The ease of installation enables using the photoelectric hot water supply not only by owners of private houses but the residents in multiple-occupancy buildings. Thanks to application of electric cable for connection instead of the pipelines with the transfer medium, the PV panels without losses of efficiency may be installed at the large distance from the heater.
See the photoelectric hot water supply systems in more details.
Comparison of photoelectric and solar thermal hot water supply
On example of system for a family of 4 persons (200 l/day)
|SOLAR THERMAL HOT WATER SUPPLY||PHOTOELECTRIC HOT WATER SUPPLY|
|Necessary area of the roof||5 m²||13 m²|
|Distance from the roof to the boiler house||critically||it does not matter|
|Problem of boiling||yes||no|
|Boiler||with integrated heat exchanger||any with the possibility for installation of a heating element and a temperature sensor|
|Assembly||rather difficult||maximum simple|
|Approximate cost of equipment (without boiler)||$2197||$2930|
|Approximate cost of assembly||$470||$290|
Solar thermal system and feed-in tariff
The especially attractive advantage is the use of photoelectric hot water supply systems in private households in combination with the feed-in tariff.
Hot water supply is one of the main users of electric energy. The financial earning capacity of the plant with feed-in tariff in private household directly depends on its own consumption. Thus, hot water supply is the factor for significant reduction in profitability of the grid-tie PV-system.
Having displaced the electric load of hot water supply with the grid-tie PV-system to solar thermal system, a household does not just save the electric energy but compensates the profit, which has not been received. Hereby, the amount of this profit turns out to be by 3 times more than the potential saving.
It looks like that in numbers:
- a solar thermal system without feed-in tariff saves the usual current tariff of 1.7 UAH/kW h
- a solar thermal system with feed-in tariff saves 0.18 EUR/kW h
The payback period of solar thermal system is hereby reduced from 9 to 3 years!
A family of 4 members consumes 200 l of hot water per day.
3,646 kW h or UAH 6,447.6 are needed at current consumer tariff per year to heat such amount of water.
The use of solar thermal system allows reducing these expenses by 2,616 kW h or UAH 4,626.
Saving is UAH 385.5 per month.
If the electric energy is sold due to feed-in tariff, the own consumption for hot water supply without solar thermal system will provoke the insufficient profit in the amount of UAH 13,655 per year.
Saving is UAH 1,138 per month.
It is sufficient to add just 6 or 8 additional PV modules to the solar field of the grid-tie PV-system in order to use the photoelectric hot water supply system together with the plant that operates due to feed-in tariff.
If the area of the roof or site does not allow arranging such amount of panels you can install the solar thermal system that would take by 2.5 times of area less.