Solar and Battery Storage Systems

Tailored to Your Needs

Looking for sustainable energy solutions for your residential home or business? We are passionate about providing eco friendly options like solar photovoltaic (PV) and battery storage systems. With the government's zero VAT rate on solar and battery installations until 31 March 2027, now is the perfect time to invest in solar energy.

Call Now

What is Solar PV and How Does it Work?

Solar photovoltaic (PV) is a sustainable technology which essentially captures energy from the sun and converts it into electricity that we can use in our homes. When a solar system is combined with a battery storage system, any energy that is produced but not needed immediately can be stored in a battery for later use. Additionally, energy can be exported back to the national electricity grid when the battery becomes full, which you will be paid for by your electricity provider. This is called the smart export guarantee (SEG).

Electricity in Your Home

Electricity is what is used to power our electrical items within our homes. The system that’s used in the UK is called alternating current (AC), and in a domestic house, it is distributed at 230 Volts (V); so that’s 230V AC. The energy captured by the solar panels is different and is called direct current (DC), which needs to be converted into AC to be used in our homes.

All our appliances - that is, anything that you plug into a socket - will have a power rating measured in Watts (W). For example, an average kettle will use 2000W, or 2kW (kilowatts - 1000W is equal to 1kW).

Anything that heats up uses more electricity than items that do not. So, a kettle, toaster, microwave, cooker, washing machine, tumble dryer, or hairdryer will use more electricity than, say, a TV, laptop, Wi-Fi router, or desk lamp. If you look at the appliances in your home, they will contain a label (or in the instruction manual) that will give you the power information.

Different Measurements

Let's discuss the difference between kW and kWh. This is important, especially when working out your electricity bill.

kW is a measurement of power.

kWh is a measurement of energy used over time, measured in kW.

Let’s use the kettle example again. The kettle has a power rating of 2kW, so if it is turned on and left for 1 hour, then it uses 2kWh, i.e., 2 kilowatt hours. However, if the kettle is only turned on for 30 minutes, then it uses 1kWh.

If our TV is rated at 200W, it would take 5 hours of constant usage to use 1kWh.

In the UK, you are charged per kWh of electricity used.

If you look at your electricity bill, it will tell you what you pay per kWh.

Example

The electricity costs 35p per kWh, and 6kWh is used in one day.

That is 0.35 x 6 = £2.10 per day. By breaking down what appliances are used and what the power rating of each appliance is, you can work out how much they cost to run. You can work out which appliances cost the most and then try to change how you use them to reduce your electricity costs.

Solar PV System Components

This list is by no means everything, but it gives you a good idea of some of the main parts used.

Panels

These are used to capture the energy of the sun. They come in different sizes and are all rated in Watts. A panel can be rated anywhere from 300W to 500W. The higher the Watts, or wattage, the bigger the panel.

If you have 10 x 375W panels on your roof, this would be a 3.75kWp system. The ‘p’ in these units (kWp) stands for ‘peak’. This means that this system is a 3.75kW system under ‘peak’ conditions (that is, when the sun, temperature and weather conditions are all optimum). In reality, this system will generate less than 3.75kW, which is why solar systems are often oversized to compensate. What this simply means is that if you only use 3kWh of electricity per year in your home, we may design a system that is 4kWp because the system will only generate this in peak conditions.

Mounting System

This is what the panels attach to. A mounting system can typically be fixed to any type of roof or even on the ground. Some installations may benefit from an in-roof system. This is where roofing tiles are removed and replaced by panels. We only use mounting systems approved by MCS in our work.

On-roof solar system.

In-roof solar system.

Inverter

As mentioned above, the energy captured from the sun by the solar panels is DC. However, AC electricity is used in our homes. Therefore, the captured energy must be converted. The inverter converts the captured DC electricity into usable AC electricity. The standard inverter size is 3.68kW, which can be installed without prior permission from the electricity network. Bigger inverters are available but require permission beforehand (more on this later). The 3.68kW rating is how much energy the inverter can convert from the panels. So, if you have a 5kWp system on your roof, only 3.68kW of this can be used at any time. It is ok to install systems larger than 3.68kW, as the generation from the panels will change daily and remember that the 5kWp system will only generate 5kW during peak conditions.

Battery

This allows any excess energy captured by the panels to be stored for later use, or to supplement the electricity used within the home if the generation from the panels is poor. This can be useful for overcast days with minimal solar energy, or to use the battery as an emergency power supply (EPS) in the form of a single socket. This can be used in the event of a complete grid power outage. You can plug in your Wi-Fi, TV, fridge or freezer.

On the other hand, some batteries do offer a complete backup to your home in the event of a power outage. These batteries can power your entire home if there is a power outage. These systems are, for example, useful when you work at home in an area with frequent power cuts or have medical equipment which cannot lose power.

It is important to remember that each battery system works differently.

Ask yourself the following questions.

Do you need a full house backup during a power outage?
Would an emergency power supply socket be enough?
How often do you have power cuts in your area?

A standard battery installation will not provide full backup power

to your home in the event of a power cut.

Solar PV - Example 1

In this example, we have a 4kWp system on a house roof with a 3.68kW inverter. Alongside this is a 5.2kWh battery storage system. The system is currently generating 1.8kW (this is the amount of solar energy captured by the panels and passing through the inverter).

But only 1.2kW is required (the property is only using 1.2kW). Assuming the battery has available capacity, the surplus 600W from the panels is stored within the battery.

The sky now becomes cloudy, and the generation from the panels drops to 1kW. The property is still using 1.2kW. The additional 200W of power now required is now drawn from the battery. During this period, no electricity has been purchased from the national grid.

The battery can provide the surplus power that the house requires until it is fully depleted. Once this happens, any extra power that is not provided by the panels is purchased from the national grid.

Solar PV - Example 2

In this example, a power outage occurs, and the battery is 50% full. A 5.2kWh battery at 50% capacity will contain approximately 2.6kWh. If we are using an EPS socket, up to 2.6kWh worth of electricity can be used. Remembering what we discussed earlier about the difference between kW and kWh, the time that this battery will last is entirely dependent on what is plugged in.

For example, using an EPS, if you use your Wi-Fi router, a laptop, and a TV, which totals 500W, then you can run these for about 4.5 hours before the battery will run out.

If you decide to plug in a cooker which is rated at 2kW, then your battery will last just over an hour!

How to Get the Most Out of Your Solar PV System?

As mentioned earlier, all systems are limited by your inverter. Let’s say that there is a 3.68kW inverter installed, which means that 3.68kW of electricity can be supplied from our solar PV and battery system (if installed) at any one time. So, if we were to turn on a washing machine with a rating of 2.5kW and then turn on the vacuum cleaner with a rating of 2.5kW, we would be using 5kW. Our inverter is only rated at 3.68kW; the additional 1.32kW of electricity will have to be purchased from the national grid. However, if we were to vacuum first, and then, when finished, turn on the washing machine, we are only using 2.5kW of electricity at any one time (although don't forget to add in your baseline-see below). If our system is generating enough power or we have enough power stored in our battery, then using these appliances will be free.

This simple way of adapting your electricity usage will allow you to further lower your energy costs, and this will also help repay the cost of having a solar PV system fitted much quicker.

Do I Need Solar Panels?

We sometimes get the question of whether you can use a battery alone, and when this would make sense. The short answer is, yes, you don’t necessarily need solar panels if you want to use a battery system. One of the main reasons would be to use cheaper overnight tariffs offered by electricity providers. This means that you can charge a battery storage system overnight and use this saved electricity during the day, without the need for solar panels.

Once you have worked out how much electricity you use during the day, an appropriate battery and inverter can be sized for your needs. This may be a more suitable option than having both panels and batteries fitted.

Battery Storage - Example

For this example, we are going to assume that your home uses 10kWh of electricity per day, and that you have a daytime tariff costing 30p kWh and a nighttime tariff which costs 10p kWh.

This example will ignore the standing charge.

10kWh x 30p = £3. Your daily spend on electricity would be £3. If we work that out per year, then the total cost is 3 x 365 = £1095

Now, let’s consider if we use a battery and charge this up using a cheaper overnight tariff and use this stored electricity to power our home during the day.

10kWh x 10p = £1. Your daily spend on electricity is now only £1. If we work that out per year, then the total cost is 1 x 365 = £365

£1095 - £365 = £730

From this example, we can see that using a battery will save you a total of £730 per year on electricity costs.

It is important to remember that each home uses a different amount of electricity each day, so there is no "one size fits all" approach when it comes to battery storage.

Solar and Battery Storage - Example

Continuing from the above example, let’s add some panels to this example. If we have a fully charged battery due to overnight charging, then any solar generation that is not required within the property will be sent back to the national grid. You will be paid for this! This forms part of the SEG. Using the battery example of 10kWh, which costs £1 for the overnight charging, if we generate enough solar to use within the property and keep the battery topped up, the excess will be exported. Let’s say that the SEG is worth 20p per kWh, if we exported 5kWh of electricity, that would be 20p x 5 = £1. You would be paid £1 for your exported electricity. Therefore, the money that you have spent on filling up your battery overnight will be offset.

Obviously, this is a simple example to highlight how the system can work. At the time of writing this guide, available tariffs offer an overnight price of 6.5p and an SEG price of 16.5p.

Applications & Permissions

Solar and battery storage installations come with two types of applications, which have to be reported to the Distribution Network Operator (DNO). The determining factor is the size of the inverter, and not the number of panels that you may have.

G98 - The inverter limit for a G98 notification is 3.68kW. You do not need any prior permission to have this type of installation carried out. A notification is sent to the DNO after the installation is complete (within 28 days). You can pair any amount of panels and any size of battery with a G98 installation.

G99 - When the inverter is over 3.68kW, then a G99 permission is required. After a system is designed for you, we send off the relevant details to your DNO. The G99 application process can take up to 12 weeks to complete and may incur a charge from the DNO. You cannot install your system until this permission has been granted.

If your house is on a ‘looped supply’ then you will need a G99 application regardless of the size of inverter.

These processes will be explained in more detail during the site visit.

Our Top Tips

Make a list of all your regularly used appliances and their power ratings
First thing in the morning, make a note of how much electricity is being used. If you average this over a week, you will have a good baseline value. Consider this value when you use your appliances during the day (this refers to the paragraph above 'How to get the most out of your solar PV system).
Look to replace any appliances with a high kW rating with a more efficient alternative (e.g., slow cookers and air fryers).
Consider using smart sockets to turn on your washing machine, dishwasher, and tumble dryer during the day when your solar generation is high.
Consider if you need both panels and a battery system - would just having a battery be enough?

£50 off your electricity bill

We can offer you a £50 discount on your first electricity bill if you switch to Octopus Energy.

Get £50 off

Please note that products from different manufacturers will be different, and it is always recommended that you check the specifics of any system designed for you.

Disclaimer: The information provided in this guide is intended for general informational purposes only. Professional advice should always be sought before undertaking any works. We reserve the right to change the information provided in this guide at any time without prior notice. The use of the information in this guide is entirely at your own risk, for which we shall not be liable.

Why Choose Solar Power?

Clean and Renewable Energy

Harness the sun's power with our solar PV systems. Solar systems provide a clean and renewable energy source, free from harmful emissions contributing to climate change.

Save on Energy Bills

Reduce reliance on traditional energy sources and lower your energy bills. By generating your own electricity, you can cut costs and decrease your carbon footprint.

Increase Property Value

Installing a solar system demonstrates your commitment to sustainability, lowers your carbon footprint, and can boost the value of your property. It's a wise investment that pays off in more ways than one.

Efficient Planning and Execution

From meticulous planning to efficient execution, we ensure that your renewables project is completed with precision and within the stipulated timelines.

Call for a Consultation