Free solar panels generate electricity for your home. The solar cell is able to convert light to electricity on
Free solar panel systems are most likely connected to the grid. This means that you'll still be able to use electricity even during the night, but it will be supplied from the grid rather than from your solar panels. The same is the case for periods of bad weather. The change in supply will happen automatically so there's no need to worry about running out of electricity. Similarly, when you're using more electricity than your solar panels are producing at any point, your electricity will be supplemented with electricity from the grid.
Solar panel installation requirements
So you're considering getting solar panels? The first thing you need to do is determine if your house is suitable for solar panels to be placed on the roof.
Most companies offering free solar panels will require a pitched roof which is approximately south-facing. By placing the solar panels facing south, the maximum amount of light possible will reach them. So south-facing will give the best performance. Some companies will allow installations on flat roofs and will place the photovoltaics at a vertical angle.
An area of about 25 square metres is required to install the solar panels. The exact requirement can be different for different suppliers so it's worth checking.
Another requirement is that there are no obstructions which would overshadow the photovoltaics. This can be from trees or nearby buildings. A small amount of shadow will usually be acceptable although this will decrease the performance of the photovoltaic system. Generally, the panels will need to be shadow-free between 10 am and 4 pm.
You need to live in an area with sufficient day-light. Contrary to popular belief, you do not need sunlight for photovoltaic panels to generate electricity. They convert light to energy not heat. So you'll even be able to generate electricity when it's cloudy, making them perfectly suitable for most climates.
Free solar panel advantages
Advantages for you
Free photovoltaic systems allow you to reduce your impact on the environment and reduce your carbon footprint. The most important reason however will be that you will be using less electricity from the grid while you generate your own free electricity from the solar panel array. As you will buy less electricity, solar panels will save you money.
How much will you save? There are a lot of variable to take into account when determining your savings. Some of these, like the weather, we can't control. However, it is possible to determine a rough estimate. From my calculations, a standard 4000 kW, 25 square metre solar array will generate 3690 kWh of electricity per year. This is equal to about £600. However, it is unlikely you'll be using all of this electricity. In principal, most solar power is generated during the summer, when your electricity consumption will be the lowest. Realisticaly, you'd be looking at a 35% use of electricity generated by the solar array. So I'd estimate you'd save about £200 per year.
How long will you be saving this amount? Solar panels have a design life of 25 years, so you could expect to save this money every year for the next 25 years. Solar panels degrade however and after 25 years they'll only produce 80% of their initial electricity generated. It is however most likely that due to increase in electricity prices, your annual saving will be maintained or increased even with the solar pv degradation. So over 25 years, you could estimate your savings from solar power generation at £5000.
If you'd like to estimate the potential savings for your specific solar array then visit my article on Estimating electricity generation and cost savings from solar panels. Please don't just rely on online calculators to estimate your potential savings. Many of these websites will try and entice you to have a free solar power system installed and they may be inflating your savings potential to increase sales.
Advantages for the supplier
So you're wondering what's in it for the supplier? Why on earth would they be spending (loads of) money installing solar panel arrays on people's roofs? And for free?
The answer is in the feed-in tariffs which were brought in by the UK government in 2010. The feed-in tariffs are the result of a change in regulation. This means that when your solar panels generate electricity, the electricity company pays you for it. So here's the catch: the supplier installs free solar panels on your roof, therefore the supplier becomes the electricity producer and they will receive the payments from the electricity company. You are effectively leasing out your roof to the supplier.
The current feed-in tarrif for retrofit solar power generation systems of 4kW or less is 43.3 p/kWh. Previously we said this type of solar array generates 3690 kWh of electricity so the solar panel supplier will receive £1598 each year for 25 years.
The supplier obviously has to pay for the initial investment in the solar panels. For the 4 kW solar array we've been discussing, the cost would be in the region of £20 000. With an income of £39 950 (20k times 25 years) and an investment of £20 000, the free solar panel supplier would make a profit of £19 950 over the course of the 25 years. This makes the supply of free solar panels a very lucrative business. (This isn't quite the whole story as the installation company will take the risk for malfunctions or maintenance requirements and they may also sell your unused solar electricity to the grid.)
Free solar panel disadvantages
Done right, free solar panel systems shouldn't have any disadvantages. However, as you're leasing your roof, it is worth having the paperwork checked by a solicitor. You should also contact your mortgage provider and advise them of your intention to have free solar panels installed.
Most of the pitfalls easily can be avoided by asking the right questions. Consumer focus has compiled an extensive list of questions about free photovoltaic panels which will make sure you avoid the pitfalls and know exactly what to expect. The questionnaire can be found here (non-referral link).