What Are Solar PV (photovoltaic) Panels?
Solar PV panels use the sun’s energy to generate 12 volt DC electricity. They are combined with an inverter which converts the low electricity to mains electricity (240 volt AC). This can then be used to power lights and appliances around the home. Surplus energy can be sold back to the electricity grid.
Solar PV systems are described in terms of kWp or kilowatts peak. So a 4kWp system would generate 4kW at peak performance (direct sunlight in the summer). Of course when the sun goes down then this drops to zero.
How Much Do Solar Panels Cost?
These types of systems are gradually coming down. In 2019 a typical 4kWp system costs around £7,264 (£6,918 ex VAT at 5%). A 2.5kWp system would be around £4,540 (source: Microgeneration Certificate Scheme data 2018/19).
There is no specific annual maintenance required for solar panels (the rain will normally wash them clean) and they have a design life of 20 to 25 years. Power inverters usually come with a 10-year guarantee so it is worth allowing for replacing it after 10 years. the current cost would be around £600 but in 10-12 years time the price should have fallen to around £500.
What Could I Save?
With a 4kW system you could gain about £300-350 per year in bill savings assuming you use 50% of the electricity generated and export the rest. The system would generate between 3,400-4,000 kWh of electricity per year.
A new scheme, the Smart Export Guarantee (SEG) will be introduced in January 2020 for new solar installations to replace the FIT scheme, abandoned in March 2019. This will offer a payment for the electricity you export to the grid but details of export payment rates have not been published by most energy suppliers. A Smart meter is needed and payments are likely to vary by 30 minute period according to energy demand.
Read the detail behind this: Solar PV Panel Payback And Costs In 2019.
Do Solar Panels Have To Be Installed On A Roof?
Installing solar panels on a roof is not always possible: in conservation areas; where the roof area is unsuitable or shaded; where the look of the house may be compromised. An alternative is to mount the panels on the ground using a commercial mounting system or even a bespoke wooden structure . The benefits of not mounting on a roof include:
- panels can potentially be mounted facing due south and at the ideal angle
- an area of unshaded ground can be selected
- cleaning of panels is easier
- installation is easier
The photo shows a 2.5 kWp array (10 panels) mounted on a wood pergola which is also used to store timber for a wood burning stove. A great alternative to a roof mounted system. To run the electricity to the house required a trench to be dug and the use of armoured cable. For more information see the very helpful Superhomes website. Note there may be planning restrictions on the height of a pergola so you should check planning permission regulations
What Else Do I Need To Think About?
The bill saving benefits from solar electricity do depend on your usage behaviour – the 50% household usage assumption we have made for solar PV generated electricity may not be realistic if you are never around during the day. That is because most electricity is produced around noon in Summer months when weekday electricity usage is low with occupants often at work or school. Studies show that generally homes export nearer 75% of the electricity and use 25%. It’s worth bear this in mind as a 25% usage level would halve bill savings at the assumed 50% level. Home-owners sometimes invest in systems which use the excess daytime electricity to heat water in their hot water cylinder or to run kitchen appliances such as dish washers and washing machines during daylight hours.
Should I Buy Solar PV Panels In 2019?
As an exciting investment no; they will suit those who have a great desire to use green electricity for some of their electricity needs. The likely payback (before you get your money back) on domestic solar investments is 20 years or more.
2019 may be a slightly better year to invest if the EU decides then to remove the Minimum Import Prices (MIP) restriction that have been applied to Chinese manufactured solar panels since 2013; the restriction has kept UK solar panel prices higher than outside of Europe. There is also a proposal for HMRC to increase VAT to 20% on solar installations. This will add around £1,000 to the cost of a 4kW system.
There are some interesting developments in battery storage technology which could also change the attractiveness of investing in solar PV panels.
See further examples on Solar PV panels
This article covers solar PV panels for electricity generation. See information on solar water heating.