Your questions answered

Questions about solar PV in general

Is there enough sunlight in the UK for a solar photovoltaic system to work?
A good quality solar photovoltaic system will actually work throughout the hours of daylight. Although they work best when it's sunny, it's not essential.

Do solar panels work in the winter?
In the UK there are plenty of hours of daylight for a PV system to work effectively at any time of year.

Obviously in the winter months there are considerably fewer hours of sunlight per day (the ratio is around 5:1). However well-sited high quality solar panels will still generate a significant level of power.

I live in the North of Scotland. Is there enough daylight here to make solar panels worthwhile?
In the North of Scotland there's an average of 900 kWh of sunlight per year, compared to 1,300 kWh a year in the South West of England. However a solar PV system should still cover a good proportion of your electricity requirements during the winter and more than enough in the summer.

What happens when the weather is bad?
Our solar PV installations are designed to work in varying light conditions, from dawn to dusk. The solar panels themselves and the inverter make the most of the available light.

How big is a typical residential system?
Most residential systems are between 2 and 4 kWp (kilowatt peak). A 4 kWh system has 16 panels, each with an output of 245 watts. As a rough estimate, for every kW (kilowatt) you should allow for eight square metres of roof area on a sloping roof. So a 4 kWp system would cover approximately 32 square metres.

What does kilowatt peak mean?
The kilowatt peak (kWp) is the power output a solar system is able to achieve when exposed to 1,000 watts of sunlight per square metre.

How long will the system last?
Solar PV systems are designed to last at least 25 years. There are no moving parts, little maintenance required and generally not much to go wrong. The weakest point of the system is the inverter, which may need replacing once over the life of the system. At today's prices, replacing this would cost around £1,000-£1,500.

Can we use a photovoltaic system to heat our building?
Only if you have electrically-powered heating.

Solar photovoltaic systems are designed to produce electricity from sunlight. You can also purchase solar hot water systems, which you can use to heat your home if it's fitted with conventional radiators or under-floor heating. These directly harness warmth from sunlight to heat water, which flows through the panels. Insta doesn't currently supply solar water heating systems.

Questions about installation

What does solar panel installation involve?
The technicians will first fit a mounting system then attach the solar panels to your roof at the optimum orientation and angle (ideally facing south and set at 35 degrees). The panels can be mounted on the ground if you don't have a suitable roof or if you have unshaded land to spare.

An inverter will be positioned inside your building. The solar panels will convert the sunlight into DC (direct current) electricity. This will then feed into the inverter, which will convert it into AC (alternating current) electricity.

The technicians will also fit a generation meter to measure how much electricity you generate. Any electricity produced and not used on your property will be exported to the National Grid.

Can you install a PV system on a flat roof?
Yes we can, using a special mounting system. However we need to be able to direct the solar panels south, southwest, southeast, west or east. A southerly direction is best.

Does it matter which type of inverter you use?
Yes, the choice of inverter is very important, as it's the brains of the system.

An inverter is a clever piece of electronic circuitry that converts the DC (direct current) generated by the solar panels into a usable AC (alternation current) electricity supply. It also maximises energy production to make the most of varying light levels throughout the day, disconnects the system from the mains at night and reconnects it the next morning. 

Some inverters on the market are only able to power up and start working when a certain intensity of light hits the solar panels. We only specify and install more efficient inverters that make maximum use of all the light available during the day.

Questions about your property

Is my house suitable for solar PV?
The ideal home will have a south-facing roof with a pitch of 35 degrees. Solar PV systems can be installed on east and west facing roofs but the efficiency of the system may be up to 10% lower.

Solar PV systems are now a permitted development right on residential properties. However if your home is located in a conservation area or area of specific scientific interest you will need planning permission. We work with planning experts at Waldon Energy to successfully resolve planning issues.

Will it affect my home's value?
In 2009 a survey by the Energy Saving Trust found that 35% of people would be willing to pay more for a home where some of their energy supply came from renewable resources. Half of those questioned were interested to know if their home was suitable for renewable energy.