Q: What is solar energy? (not too long please!)
A: Solar energy is the radiation which comes from the sun. This comprises around 55% visible radiation, which we can see. Most of the remaining solar radiation is infrared radiation. A tiny amount is ultraviolet radation. Solar water heating panels work on visible and infrared radiation, so they use most of the sun's spectral output. When this radiation hits the dark inside of a solar panel it heats it up. This then heats your water.
Q: What is the maximum heated water temperature that the solar panel can achieve?
A: Water and steam at 100C is theoretically possible if you were to switch the pump off on a hot sunny day. But please don't do this. With the pump running we have only ever achieved 85C ! But 160C internally for the panel if left dry in the sun, is possible.
Q: What is the life expectancy of the evacuated Tube system and does it come with a guarantee?
A: Intended design life of the whole system is 20 year minimum.. I would expect the pump to need replacing before 20 years, however, since it is the only moving part and moving parts are the most subject to wear.
Q: I have a bungalow with a flat roof ground floor extension. The upper, sloping roof could be used to support a panel but it does not receive the sun all of the day. The flat roof receives full sun from dawn to dusk. Installation of the pipes would also be easier from the flat roof as they could be taken up under the tiles to avoid drilling. Is it possible to have the solar unit free-standing on the flat roof? Would its own weight, plus water, be enough to hold it if the mounting brackets were fixed to a wooden frame?
A: Flat roofs are fine for solar water heating panels but you need to make sure it will not take off airborne and that it will not sit in any puddles. You will need an angled A-frame for support. We can make these at any angle if you want. The weight itself is not enough to prevent flight! On some flat roof plus A-frame installations we use 2-3 tonne stainless steel straining wires (from any ships chandlers) to keep it sitting tight and to do away with roof penetrations.
Q: You provide lots of lovely information but as regards payback time you just say that it is shorter. Do you have some estimates of the payback time?
A: The issue of payback is a complex one and has many different variables, not least the type and cost of fuel that the system would be displacing.Others are:
the latitude at which you live
the microclimate
the orientation of your panel
the thermal efficiency of your boiler - if you have one
what proportion of the delivered solar hot water you actually use
the annual fuel price inflator you apply each year
the cost of the finance or lost interest on the capital spent on the installation
how much of the cost you consider to be a capital value boost to the value of your home and a few others besides. All this makes for gigantic spreadsheets with assumptions compounding upon each other and a huge opportunity for financial trickery . We estimate that for mains nat gas (not more expensive bottled gas) you are unlikely to exceed 100 euros on fuel savings and perhaps save another 15 euros or so per annum on boiler life extension.
Q. What about underfloor heating?
A. For integrating Evacuated Tubes with underfloor heating, You have install a plate Heat Exchange that will transfer the heat from your hot water system to your heating system. The obvious drawback with using your solar panels for heating is when you want the heat the sun is not there (i.e, winter). Therefore we recommend using your panels solely for hot water.
Heating Solutions Ltd
Solar Panels – Underfloor Heating – Heat Pumps
29 Suil na Habhann, Mill Rd, Limerick, Ireland
Tel: 086 3823062;
Fax: 061 346011
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