Solar PV systems are usually mounted on to the roof of your house, absorb the energy radiated by the sun and turn it into electricity you can use to run your home appliances.
Solar PV systems reduce your electricity bills as you will be creating your own electricity, they also save greenhouse gasses such as Carbon Dioxide (CO2) from being released into the atmosphere and since January 2020 you can get paid by your energy supplier for any surplus electricity that you export to the grid.
How do solar PV systems work?
In order to understand how a solar PV system works we need to understand a few measurements used when talking about electricity.
Voltage: the unit of electromotive force and is measured in Volts. It can easily be described as the pushing force of electricity.
Current: the rate of flow of electricity and is measured in Amps.
Power: the amount of electricity used in a given time. It is measured in Watts and in its simplest form is Volts multiplied by Amps.
Solar panels work by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity.
The panels are made of solar cells which are basically a sandwich made up of two slices of semi-conducting material, usually silicon.
During manufacture an electrical field is generated between the two layers of silicon, so that when a photon of sunlight knocks an electron free it is forced out of the cell and into the wires connecting the cells together.
Solar panels produce Direct Current (DC) electricity similar to that found in the batteries in your TV remote control. A typical solar panel can produce around 40Volts of DC electricity.
Solar panels are connected together to create “strings”. These strings are connected to an inverter to form a solar array. The number of panels in each “string” varies according to how many volts and how many amps the inverter needs to operate efficiently. This is all worked out by your solar design engineer.
The solar inverter is the brain of a solar PV system. It takes the DC electricity generated by the solar panels and converts it into usable Alternating Current (AC) electricity that can be used in your home to power appliances.
The inverter contains a lot of electronic circuits to make sure that the electricity you generate is of a suitable quality for your home appliances to use without causing damage to them.
The inverter is also there to protect the National Grid. If the energy you exported to the grid was not of the right quality, it could cause power failures or damage to the network or appliances connected to it. The inverter monitors the quality of the energy to make sure that it remains within the strict guidelines that our distribution network needs in order to operate efficiently.
How do I benefit from a solar PV system?
All of the energy generated by a solar array is available to use in your home, or store in a battery for use later when you need it. Any energy that is not used, or stored, is exported to the National Grid where it helps to reduce demand from power stations.
Every unit of electricity that is used in your home is a unit of electricity that you do not buy from your electricity supplier and will be seen as a saving on your electricity bill. The average cost of electricity in the UK is around 14.5p per unit, so the savings can add up quickly.
From January 2020, the UK Government introduced the Smart Export Guarantee (SEG). Energy suppliers with over 150,000 domestic customers must buy any exported energy from you at a rate above zero. So, as well as savings in your bill, you can also get some payments back from your supplier.
Each unit of electricity you generate yourself will also save carbon dioxide emissions from being released into the atmosphere from fossil fuel fired power stations. At the time of writing, each unit of electricity generated will save 0.2556 kgs of CO2 per year.
So, what next, how do you get your own solar PV system?
Before you invite an installer to come and talk to you about what is possible, you need to understand how much electricity you use, when you use it and how much it costs you.
There are a number of ways that you can find out this information.
First, look at your electricity bills. These will give you an idea of how much energy you are using and how much you are paying for it. Your electricity bill will normally show a standing charge, this is the rate you pay your supplier every day for electricity to be available to you, and your unit cost, which is the price you pay for every unit of electricity. Currently this will be around 14.5p per unit.
Electricity is measured in kWh and so this will tell you how much you have used.
The more electricity bills you can look at for your home, the more accurate you can be with how and when you use electricity.
This approach will give quite a broad idea of how many solar PV panels you might benefit from.
In order to be more accurate, we need to understand when you use electricity during the day. If you have a smart meter fitted you may be able to get this information from your energy supplier.
If you don’t have a smart meter, then you could use a home energy monitor which can be bought at a relatively low cost form our online store. Monitors like the GEO PVII can be used for recording your energy consumption or the generation of your solar PV array after it has been fitted and so can be a useful purchase.
The device shows how much energy is used in 15-minute time intervals so your energy use can be matched to a solar PV systems generation.
Speaking to a professional
So, now you understand how much energy you use, when you use it and how much it costs it is time to talk to a professional.
Invite a reputable local installer to talk you through what can be achieved with your home.
Typically, SaveMoneyCutCarbon will start this process with a desktop design.
Without having to visit your home, we can use aerial imagery to work out roughly how many solar panels will fit and how much it will cost.
This can give you a good idea about whether or not solar PV is right for you.
Although ideally, solar PV systems would be installed facing due South, useful amounts of energy can be generated from systems facing East and West as well, so let a professional designer tell you what is possible.
If the proposal is affordable and you want to move forward, then our system designer would need to visit your home.
Before we can provide your final system quotation, we need to check that your house is how it looks on the aerial image. Sometimes these images can be a little out of date and you may have added a roof light when you converted the loft into a bedroom, or the tree next door planted has grown quickly and over-shadowed your roof. These all need to be checked to make sure the solar PV system will work properly for you.
Our designers will take a look into your loft to look at the roof structure and make sure that it is suitable. We also need to take a look at your consumer unit so that we can check how the solar PV system is going to get the electricity it generates back into your home.
Then we can provide you with an Investment Ready Proposal. This will set out everything we have checked, any specific requirements you have asked for and will detail how we expect the solar PV system to perform, what savings you can expect and how much carbon dioxide you will be saving.
When you are ready to proceed, our installation team will make light work of your installation. Typically, a domestic solar PV system can be completely installed in 1 day, although more complex designs may take a little longer.
How much could it cost and what will I save?
The average solar PV system in the UK consists of around 12 solar panels on the roof and will be capable of generating around 3,150 units of electricity every year. That could save over 805 kgs of CO2 being release into the atmosphere every year just from your home.
For a typical domestic property, being a 3-bed semi-detached, expect to pay between £4,000 – £6,000. This will depend on any particular requirements you might have or extras that you choose to install such as a solar water heating diverter.
The cost of installing solar panels has fallen by around 70% since 2010 when they really started to become popular.
You can expect to see your electricity bills reduce by around 50% and maybe even more with a solar battery added to your system.
Since the UK Government started the Smart Export Guarantee at the beginning of 2020, electricity suppliers will now have to pay you for surplus energy exported to the National Grid. There is no set rate for this, but it must be above zero. At the time of writing the highest rate was being paid by Social Energy at 5.6p per unit. Assuming that 50% of the energy generated in the above example was exported, a payment of around £88 per year could be expected.
How long will a solar PV system last and does it need maintenance?
Solar PV panels are designed to last for at least 30 years, and many are backed up by manufacturer’s warranties to give you piece of mind.
Solar inverters are likely to need replacing once during this time. A typical 3kW domestic solar inverter will likely be provided with a 10 year manufacturer warranty and will cost in the region of £500 to £700 to replace depending on the type of inverter and difficulty of access.
Solar PV arrays do not need much in the way of maintenance. Ensuring that the solar panels are clean and free from shade is key to maintaining good performance. Many local window cleaners are able to clean solar panels and have the right equipment for doing this properly. In the countryside where panels can get dusty around harvest time, it might be necessary to have your system cleaned once per year.
The solar inverter should be checked annually to make sure that it is free from damage, is not showing signs of over-heating or strain and that there are no error codes recorded.
This can often be done using the inverter manufacturer’s monitoring software, which will connect to the internet through your home WiFi.
SaveMoneyCutCarbon can help you with the maintenance of your solar pv array, whether that be diagnosing system faults or annual health checks, our dedicated team have over 10 years of experience in working with these systems.
Is there anything I can add to my solar PV system?
So, now that your solar PV array is installed and generating sustainable, renewable energy for you what else can we do to maximise it?
There are still a few items you might want to consider to truly maximise the benefit and set you firmly on the path to self-sustaining.
Solar water heater diverters are a cost effective first step to energy storage. The cheapest form of energy storage is your hot water.
If you have a hot water cylinder in your airing cupboard, you may be able to fit a solar diverter. This handy little device watches the performance of your solar array and if you are exporting surplus power, it will turn on your immersion heater and heat your hot water for free.
You can buy a solar hot water diverter for between £300 and £400 and they can be fitted by a local electrician or by one of the SaveMoneyCutCarbon team.
Heating your hot water with your surplus solar can save you up to £250 per year from your energy bill.
Or, if you are ready to tackle energy storage like the pros, maybe a solar battery store is right for you. A solar battery will store surplus energy and release it when you need it, in the evening or if your solar array cannot quite keep up with your consumption.
Choose the right solar battery and you might still be able to power those essential household appliances like the family TV or mobile phone chargers, in the event of a power cut.
A solar battery can be quite expensive to install so consider the benefits carefully, perhaps take some time to read our useful guide on solar battery storage for the home.
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