Solar PV in Northern Ireland?

Solar panels actually work on daylight as opposed to direct sunlight. Even cloudy days will generate significant amounts of electricity. Although hard to believe sometimes our sunshine levels are equal to middle England where solar has been increasingly popular over the last few years.

 

How do solar cells produce electricity from light?

A tilted surface can collect more energy than a flat surface, depending upon which direction it is facing. A surface tilted towards the South at 30 will intercept around 11% more light energy than a horizontal surface.

A home of 250 sq. m, built with modern levels of insulation will have an annual space heating demand of around 12,000 kWh, and a domestic hot water demand of 2,000 kWh, for a total heating demand of 14,000 kWh. Average electricity demand is estimated to be around 4,500 kWh/year.

 

A single roof pitch of the same house will intercept around 140,000 kWh of light energy each year – more than six times the energy used.

 

How much power can a Solar PV system generate?

PV systems are typically rated in kWp (kilowatt peak) which indicates the combined potential capacity of all the PV modules installed under prime conditions.

Roughly speaking, if a solar PV system faces due south and is installed at an angle of 30⁰ and is unshaded, each installed kWp can be expected to produce around 850kWh (units) of electricity per year in the Northern Ireland. A 2kWp system would thus produce approximately 1,700kWh / year, around half of the annual electricity consumption.

 

Optimal location for Solar PV panels on buildings

Your roof should ideally face due south at a tilt angle of around 30° from the horizontal to give the best overall annual performance. Installations at any pitch and facing anywhere to the south of due east and due west are feasible, although output and income will be

reduced. Installation is not recommended on roofs facing north.

 

 

This table below shows the percentage of maximum performance if installed at a different orientation and tilt:

 

 

Seasonal Performance

The chart shows a typical seasonal spread of energy generation for a system of 2.5kWp facing south. The winter months generate significantly less electricity compared to the summer months.