Solar collector controlers KSK-2

Solar collector controller KSK-2 is designed for controlling solar-powered water heating system.

Main technical parameters

Power supply voltage	5V ± 5%
Outer temperature	5 - 50 °С
Maximum outdoor humidity	85 %
Inputs for temperature sensors	2
Type of temperature sensors	TSM 100, TSP 100
Temperature scale	0...-150 °С
Inputs for flow sensors	1
Flow scale	0 – 7.6 m³/h
Controller outputs	2
Maximum voltage / current of controller outputs	40V/A

Scheme of solar-powered heating system is shown on Fig. 1.

Controller KSK-2 provides:

• Switch on/off the circulation pump at a certain predefined temperature difference in the collector and the boiler;
• Switch on/off the reserve source of heat (heating circulating pump, electric boiler, etc.);
• measuring the current flow rate, current collector thermal capacity, calculation of the total amount of heat received from the collector (provided a sensor acquisition costs).

Operation results of household solar-powered water heating system are discussed below. Heating system was assembled due to a typical scheme with forced heat-carrier circulation.(Fig. 1).

Collector is flat of type KSP-3 manufactured by Zaporizhzhya Production Aluminium Plant, with area 1,5 m².
Boiler - Dražica ACS 200 NTR/BP with two heat exchangers and electric heater.
Gas boiler Aton AOHVM - 10EV is used as a backup heat source.
Collector is oriented by 200° azimuth (South West) at an angle 11° to the horizon.

Controller KSK-2 produced by "KatrLess" is used along with resistance thermometers and flow sensor to manage the solar-powered system. Water is chosen as heat carrier because, as was convincingly proved in [1], flat collectors are effective only at outdoor temperatures above zero. Water usage reduces system cost and allows to calculate the amount of obtained heat by generally known simple formulae.

Energy measurements obtained during operation of the collector are presented on Figure 2. Minimums of energy in the diagram correspond to cloudy days, maximums are obtained on sunny days. Moreover, gas consumption chart is clearly in strong correlation with energy diagram. That is, the minimal energy obtained by the collector on cloudy days corresponds to the maximum consumption of gas and vice versa.

Practice shows that 200 liters of hot water is enough for a family of four per day if used economically. The diagram demonstrates, that in a sunny day collector produces about 6 MKal, allowing to heat 200 liters of water by 30 degrees. Thus, in summer even a single solar collector of area 1.5 m ² can provide economical family with hot water.

It should also be noted that solar-powered heating system must necessarily be equipped with back-up source of heat (electric boiler, gas water heater, etc.), as cloudy, rainy weather, the amount of energy obtained from the collector may be insufficient.

[1] V.F. Gershkovich, Solar-powered water heating systems. Design guide. KievZNIIEP, 2006. (in Russian)