How much will I save by putting solar panels on my roof?
Question: I’m keen to make my house energy efficient and am considering buying some solar panels for my roof – is this a good idea and will I save much on my energy bill?
A Fitting a solar hot water heating system is an excellent way of making your house more energy efficient as it reduces the amount of fuel used to heat hot water.
In the summer months, a properly designed and installed system will provide all of a household’s hot water requirements; it even boosts the water temperature during cloudy days in winter.
A solar system with 6sq m of panels, to suit a house with four to five occupants, will cost from €5,000 to €7,000, depending on the specification and cost of installation. As a rule of thumb, one square metre of solar panel on your roof gives the equivalent of more than 100 litres of oil in free solar energy per year, so a typical system as outlined could save in the region of €600 per year in heating costs.
The higher your hot water usage, the more beneficial a solar hot water system will be, as more “free” energy will be used (source SEAI).
Fitting solar panels is normally exempt from requiring planning permission, subject to certain conditions, but fitting them to a protected structure (formerly known as a listed building) will require permission.
A number of factors have to be considered before fitting a solar water heating system. Firstly, take care when choosing your supplier and installer. The installation should be carried out by an experienced installer and the system should have a recognised quality assurance label. If in doubt, the Sustainable Energy Authority of Ireland’s website ( SEAI.ie) has a list of approved installers and approved systems.
Panels should be sited on an area of roof not overshadowed by trees or other buildings; fitting panels facing south at a pitch of 45 degrees will achieve maximum efficiency. (Systems will still operate well on roofs with a 30-60 degree pitch and facing roughly southeast to southwest although there is a slight drop in performance. )
Many types of panel systems are available and most people choose between a flat plate solar collector or an evacuated tube system. Flat plate collectors fit on or into the roof and are generally considered more attractive than the tube-type collectors but tube-type collectors are lighter and generally more energy efficient due to the larger surface area of the tubes in a given panel area.
A new hot water cylinder will normally be part of the system. This would preferably be sited in the same location as the existing cylinder to reduce the amount of work to the existing heating pipework but these cylinders are normally a lot taller than existing cylinders and alterations to the hot press or utility room may be required to suit the new cylinder and control unit. A range of other measures is available to reduce energy consumption in dwellings and professional advice should be sought in relation to which of these measures will best suit your property.