How are hot water requirements calculated and how is the solar water heater sized?

The hot water requirements are calculated by taking into account the number of people living in the house and the size of the hot water cylinder. Each person living in the home is calculated at 50 litre’s per day. The solar panel is then sized to heat the size of the cylinder, taking into account the average climate conditions and the orientation of the roof; south, south east or south west.

What is the average size of a solar panel?

In general the size of a solar panel in based on the number of people in the household. This is usually 1 – 1.5sq m per person in the house. Therefore an average 4 person household would need between 4 – 6sq m solar panel.

What percentage of the hot water requirements will be covered by the solar panel?

In general the size of a solar panel in based on the number of people in the household. This is usually 1 – 1.5sq m per person in the house. Therefore an average 4 person household would need between 4 – 6sq m solar panel.

Is the location of the solar panels (orientation, tilt, visual aspect) appropriate?

Yes. The panel should be mounted at 40% (typical roof tilt) and be south, south east or south west facing. If the house has a flat roof a special mounting kit is provided to ensure the correct tilt. The panel is surface mounted.

Is there any disruption of the building structure required to install the system?

Minimal disruption is caused on the roof as the unit is fitted on the surface. A Dual coil cylinder is sited in the house unless the existing cylinder is used. This will require some pipe work. The entire installation takes approximately one day.

How is back up heating provided?

Back up heating is provided by any other means such as oil boiler, solid fuel stove or wood pellet stove. The cylinder is fitted with an immersion heater for use when the boiler is not required.

Can the solar collector heat water to a high enough temperature? What happens when there is negligible solar power available?

Yes, the solar collector can heat the water to a high enough temperature. In good weather it can even bring water to a boiling point. Generally this is not necessary and so the system should be designed to provide a daily temperature rise of around 25-30^oC in the summer. Sizing a domestic system that can bring the cold water up to 60^oC in a single day is not logical, because if hot water is not used for one day, the following day the system will be boiling and dumping hot water via the temperature relief valve. This is both a waste of energy and water! If the external conditions are overcast the water in the cylinder will be automatically heated by the alternative heat source to the required temperature.

Do all the materials used conform to the solar system manufacturers specifications?

Yes.

Is the system protected against overheating, freezing and excessive pressure?

Yes.

How long does the installation take?

Typically, an installation can be completed in one day; this may extend to two for more complex jobs.

What is the manufacturer’s warranty period?

Five years.

Is solar water heating a viable alternative to gas or electricity?

Solar should not be seen as an alternative to gas or electricity, but rather a supplement. Solar cannot totally replace the need for gas or electric heating as there are sometimes days when there is little sunlight. When averaged over a year, a correctly sized solar system can provide 60%-70% of a household’s hot water needs. The hot water system can easily be automated so hot water is guaranteed regardless of sunlight levels.

How long will it take to recoup my investment?

The solar collectors are much more affordable than many other solar hot water heaters. Depending on your location (solar levels) and current hot water usage the annual electricity or gas saving will differ. However in a normal household that spends 25% of its electricity bill on hot water heating, the full cost of the purchase may be recouped as quickly as 4-5 years in reduced bills.

Will water be heated on a cloudy day?

Yes, although the heat output of the solar collector is reduced on overcast days it will still be able to provide heating. If it is a heavily clouded day or raining, then more gas or electric boosting may be required to maintain water at the required temperature. This system will be automated so you do not have to worry about running out of hot water on a rainy day.

Are the solar collectors noticeable on the roof?

If only the collector is mounted on the roof it should blend into the roof design quite well.

Can solar collectors be mounted on a flat surface?

Yes, they may be mounted on a flat roof.

Will the solar collector be a fire hazard during hot, dry weather?

The solar collector’s components are all high temperature rated and non-flammable so even during strong sunlight with the circulation pump turned off (stagnation), the system will not catch alight or give off any sparks. The majority of the solar collector’s components are stainless steel, aluminum, glass or glass wool.

Where can I get an application form for the Greener Homes Scheme?

You can download it from the web at www.sei.ie/greenerhomes or at www.solarroofinstallations.com

Is there a specific list of products and installers for the scheme? If so where can I find the list?

Yes, registered product lists and a registered installers list are available on the SEAI website www.sei.ie/greenerhomes and through hard copy from SEAI by calling 1850 734 734.

What is the installation procedure?

Plumber will change cylinder (in an existing house) to a dual coil in your hot press. In a new build we provide cylinder and plumber fits it.

1.      Fitters then fit the panels onto the roof.

2.      Pipe work from the panels to the cylinder is then done by the fitters.

3.      System is filled with solar fluid.

4.      Commissioned on the same day.