Solar / Thermal

Solar hot water heating systems can deliver up to 70% of the hot water requirements for an average household. Investing in solar energy is an investment in the future of the environment and should add to the resale value of your property. By using solar energy to heat domestic hot water you will be helping to reduce our dependence on fossil fuels while at the same time improving the energy efficiency, and potentially the value of your home. In particular solar energy scores positively with the new BER - Building Efficiency Rating scheme.

Flat panels and evacuated tubes are available from Heat Merchants branches nationwide.

Q: What is the occupancy of the dwelling & how do I size a system for same? How many people will be living in the house, this will determine the size of the cylinder. (Rule of Thumb is 50litres per person). On determining the cylinder size you can then select the quantity of panels to meet the Hot water Demand. (Rule of Thumb is 50 litres equals 1 m2 of Aperture area)

Q: What type of Cylinder have you got? Low/High Pressure Single/Dual coil? What type of cylinder is already installed in the house, is it standard copper cylinder with 1 coil or 2 coils or high pressure similar. You need either a copper cylinder with 2 coils 1 suitable for Solar (High Temperature & high Pressure) or a Stainless Steel cylinder c/w 2 coil 1 for solar panels & the other for an alternative heat source.

Q: Where are the South, Southeast, and Southwest facing on the dwelling? The next most important piece of information is what roof the panels can be fitted on. The ideal facing roof for maximum exposure is south facing, then South East, then South West. This can be done by either going to site with a compass or looking at the ordnance sheets & finding south on that.

Q: Will the required amount of panels fit on the roof space & what size are the panels? In order to be sure that the solar field will fit on the roof space you will have to either physically measure or scale it out on a drawing of the said roof. An allowance must be given to the connection of the panels at each side & in the middle along with min clearances from the ridge & ends of the roof.

Q: What type of pipe work will be required? You can use either Copper pipe work with dry compression joints covered with 19mm wall high temperature Kaiflex. With this you need to tape the insulation joints & run a 2 core cable from the roof to the solar controller. The other pipe work option is to use the KaiFlex S/S pipe kits. This is made up of Stainless Steel corrugated pipe covered in the high temperature insulation & has the 2 core cable included in it.

Q: What type & quality of insulation should be used? As mentioned above the best form of insulation is 19mm wall High Temperature/Solar grade Kaiflex insulation or equivalent. Cosytube will not be acceptable as it will melt in the summer Temperatures. Also PVC coated copper is not suitable as the PVC coating will melt during the summer temperatures.

Q: Why do we need the extra thick pipe insulation? First and foremost it is required to prevent heat loss from the pipe work so as all possible heat can be transferred from the roof to the cylinder. The other main reason is that the temperatures in the pipe work can exceed 150 degC during the summer months thus exposed pipe work needs to be heavily insulated to prevents any melting or burning of materials that may come in contact with the pipework.

Q: What is the Electrical requirement? The total electrical requirement to operate a solar heating system is a fused 220v switched spur box located beside the solar controller. All other electrical details are taken care of in the Basic Solar Controller. 2 core cable from Collectors to Controller used for the purpose of transmitting the temp readings.

Q: What is the purpose of the Over Voltage Protector? The purpose of the over voltage protector is to protect the Solar Basic controller, from lightening that may strike the panels. It will blow the Over-voltage protector & save the Controller from been replaced.

Q: Do we need a mixing valve & Why? Yes ideally you do need the Mixing Valve. It is required because to maximize the solar gain you may need to store your hot water at anything up to 80 DegC. This is too hot to send out to taps, showers etc so therefore you use the mixing valve on the hot outlet of the cylinder & mix the temperature of the water down to a safer level (38deg) so as no one can get scalded.

Q: What Controls do we have on a Solar System & how do the Controller/Sensors work? On most systems you have 2 sensor points & a Main control unit. The purpose of the control unit is basically it acts as a programmer, you can set various parameters in the controller, the most important being the stored temperature of the water in the cylinder. The 2 sensors are located in 2 different places on the system 1) up on the roof at high level on the panel & the other at the lowest point in the cylinder. What happens then is the controller will check the temperature of the cylinder & compare it to the temperature on the roof, if the temp in the cylinder is 7 Deg C lower than what is on the roof then it will turn on the pump & start heating the water until it is up to set temperature (65 Deg C).

Q: What can I do if I don’t have the correct facing Roof? There are a number of different solutions to the above problem. Firstly you can compensate for the incorrect roof by putting extra collectors on the roof. Secondly you can if possible put the panels on a prefabricated frame on the ground, ensuring when the frame is constructed that it is facing south. Thirdly you can install Vacuum tube on the incorrect roof & then with the aid of a compass you can rotate each Tube so as it will be facing south & thus pick up the Maximum solar gain.

Q: Who can install a Solar Panel System? The people most qualified to installed are installers that are SEAI approved and have attended the relevant Manufacturer’s training courses.

Q: How do you transport them? Again there are a number of ways to transport the panels from store to site.

  • They can be stacked vertically as they come in from the feeder.
  • They can be stacked flat on top of one another with some cardboard between them so as not to scratch them.
  • They can be stacked on the side BUT it is very important that a piece of timber is placed underneath the Panels top and Bottom so as the connection pipes do not get damaged.


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