Solar FAQ's

 In this section we will try and answer some of the common questions about solar panels and solar heating. Feel free to contact us if you have any other questions.

How much energy can solar water heaters supply?

A 6.0m2 flat plate solar water heater from Pure Energy Technology can provide up to 2,500 kilowatt-hours of energy annually. This is equivalent to having a 3KW hot water immersion heater switched on for almost 2 ½ hours EVERYDAY 365 days per year – a significant saving!  Pure Energy Technology can provide simulations using the Irish weather data to show the energy obtainable for any size of solar system.

Do solar water heaters work in Winter?

Yes, solar water heaters will heat water to a certain degree almost every day of the year. Even in December, a solar water installation can typically heat a 150-litre body of water from 8°C to approximately 20°C. Various factors can influence the amount of water a solar heater system can heat.

These are the ambient water temperature, the number of hours of light and the intensity of the light.

How much Hot Water can a solar water heater provide?

A solar water heating system can provide between 95 to 100% of all your hot water needs during the summer. In the Spring and Autumn, 60% -70% of the hot water usage can be provided and in winter this figure is 10-20%. The ideal installation will provide approximately 65% of the hot water needs on average annually. In addition, solar water heaters can heat water above 80°C. when the light is bright.

Does Ireland get enough solar energy to make solar water heaters viable?

Ireland has the solar energy equivalent to that of Paris. This energy is provided by both direct sunlight (40%) and indirect sunlight (60%).  This means that even when the sky is overcast, the sun's radiation (sunlight) is available at ground level and can be converted into useful heat by solar water heaters.

What are the running costs?

The running cost of solar water heaters is almost non-existent.  The only energy consumed by the whole system is a small circulation pump.  If the solar system was providing hot water to the hot water cylinder for 10 hours per day, every day of the week, then a typical circulation pump would cost approximately 20 cents per week to run.

SIZE AND PLACEMENT

What size solar water heating system should I install?

The number of occupants and their individual requirements determines the size of the solar water heating installation size.  A rule of thumb would be 1.5 m2 of flat plate collector per person or 0.8 m2 of CPC (Mirror reflector) vacuum tube per person.  Contact Pure Energy Technology for assistance.

Where can I place solar water heaters?

Solar water heaters can be placed on a roof, on a wall, or on the Ground. The roof is the most common location used for solar since it is normally unused space and it keeps the panels away from used areas.  Wall mounting is often utilised if there is not enough suitable roof space.

What direction should solar water heaters face?

South-facing is best, but there is virtually no reduction in energy output from South-East to South-West. There can be as little as a 15% annual decrease if they face directly East or West when compared with South-facing installations.

Can they be fitted to an existing house?

Yes. In order to fit solar water heaters to an existing house some of the slates (or tiles) must be removed from the section of the roof where the panels will be situated.  Alternatively the panels can be mounted on a frame and placed at ground level outside the house, or on a suitable wall. The existing hot water cylinder can be used but it is often advisable to install a bigger one, with two heating coils.

HOT WATER CYLINDER

Is the type of hot water cylinder important?

Yes, in fact it is very important. It must be large, well insulated and must have two heating coils, one for solar and one for an alternative heating system.  Pure Energy Technology can supply suitable hot water cylinders.  The larger the cylinder, the more FREE hot water can be stored. The better the insulation, the longer the storage period.  Stainless steel cylinders are better than glass lined steel because stainless steel is maintenance free.

OPERATION

I have a Heat Pump.  Are solar water heaters of any use to me?

Yes, heat pumps and solar water heaters have different functions.  The primary function of a heat pump is to heat space but it can heat water cheaply, much cheaper than oil, but only to approximately 55°C.  Solar water heaters heat the water to full temperature virtually FREE and will do so for many decades with virtually no cost apart from the installation cost. Solar water heaters can heat water to 80°C and above.

Can I supplement my heating system using solar water heaters?

Yes, it is possible. However we don’t recommend this at least on the initial installation. Solar radiation reaches its maximum level in the Summer months when heating demand is at a minimum. The supply of solar energy falls to its minimum level in the Winter when heating demand is at a maximum.

Pure Energy Technology believes that payback may be somewhat longer than with a system that is installed for domestic hot water purposes only. Supplementing a heating system with solar water heaters, in addition to providing domestic hot water means that the solar water installation will need to be significantly bigger. This increases the cost but, as is the case with providing domestic hot water, energy taken from the solar water system will essentially be at zero cost.

Is planning permission needed?

Planning permission is no longer required for solar installations on domestic buildings provided that the installation is 12m2 or less.  Further information can be found on the Department of the Environment website here.

What is the life span and warranty?

Solar water heaters have a long life span due to the lack of moving parts. The outer casing of the panels is made of aluminium, which does not degrade over time. The only moving part (i.e. more likely to wear and break) is the circulation pump that should last typically 10-15 years and is a common, low cost item that is easily replaced by any plumber or handyman. All PURE Solar Panels have a 10 Year warrantee covering functionality.

Does the solar heating system require maintenance and do you provide maintenance contracts?

There is no need for maintenance contracts.  Solar systems are very reliable, fully automated and with few moving parts.  If a customer would like a maintenance contract, it can be arranged.

How much space do solar panels need?

Please see our Downloads section for Panel dimensions.