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How Many Solar Panels And Batteries Do I Need?

Are you presently considering adding a solar system to your home? With several homeowners in the UK using solar now, many more are realizing the numerous benefits they stand to derive by getting one. Therefore, if you’re thinking about adding the system to your home but do not know where to start, you’ve come to the right place.

Here, we’ll help you calculate the number of solar panels and batteries you’ll need to power your home. Starting from the panels, you can begin by taken into account everything that makes use of power in your home to get a good idea of how many you’ll need.

• Firstly, you’ll have to determine the number of watts you use. Simply go through your utility bill for kilowatt-hours (kWh). This varies amongst homes and being able to identify your daily average energy usage will assist you in getting your solar needs.

• Secondly, you have to determine the peak sunlight hours - having in mind that the solar panels only work when under direct sunlight. Once determined, you can then multiply the figure in hours by your home’s hourly energy usage and divide by your selected solar panel’s wattage.

Generally for a 1500 square foot house, you might need around 15 to 18 solar panels to cover the house’s electricity.

Meanwhile for batteries, there are also some factors to be considered to determine the number of batteries you’ll need for your house. These factors include your home’s power or electricity usage, the period of time in which the battery will be used as well as the battery’ specifications. Once done, you’ll be able to calculate the number of batteries required by your home.

The importance of selecting the right size battery for your home simply cannot be overemphasized. A lot of home and property owners are facing this challenge and understandably so. Selecting the right battery size for your needs depend on a number of factors which includes your motive for adding a battery, your electricity usage, your budget as well as your panel array size, be it new or existing. In this post, we’re going to take you through some of these factors to help you determine the right battery size for your home or property. Let’s take a look!

• Your motive for getting a battery. While most people purchase a battery to wipe out their need to purchase electricity from the grid with the hope of making some savings, others add a battery so as to enjoy backup power. There are also some who just needs it to power their home with solar energy. It’ll not be economical to size a battery to effectively take you off the grid, but if your motive is to make savings, then you’ll should expect to purchase some electricity from the grid during the year.
• Electricity usage. The average household uses about 16kWh of electricity on a daily basis. During the daylight hours, most of these household will use a third of their electricity when the solar panels are still generating electricity, while the remaining two third are purchased from the grid. In other words, you’ll require a minimum of 10kWh battery capacity if you were to use a battery to power the electricity you purchase from the grid.

For a typical British household, you’ll most likely need a 5kWh solar power system which normally generates about 17 to 21 kWh on a daily basis depending on your location in the UK.

In theory, you can fit solar panels yourself. In practice, it’s worth leaving it up to the professionals.

If you get DIY solar panels and install them on your roof yourself, you won’t be able to apply for the government-backed Smart Export Guarantee (SEG). The SEG pays you for every unit of electricity you generate and send back to the grid, so it’s a scheme well worth signing up for. However, you must have your solar panels installed by a Microgeneration Certification Scheme (MCS)-registered engineer or company, so you’ll miss out if you install the solar panels by yourself.

The other thing to consider about installing solar panels yourself is that you’re dealing with electricity. Electricity is extremely dangerous if handled incorrectly, so if you don’t have any qualifications in working with electricity you could be putting yourself and your family at risk. Connecting DIY solar panels yourself and doing it incorrectly could mean that you give yourself an electric shock or cause a fire. If your home is damaged due to a fire caused by solar panels you’ve installed yourself, it’s unlikely that your home insurance company would pay out.

Before having a go at installing your own solar panels, do some quick sums to see how much money it could really save you. A 3.5kW DIY solar panel kit will cost around £4,000-5,000. According to the Energy Saving Trust, a home in the South East of England where most occupants are out all day until 6pm would save around £100 a year on their electricity bills. That means that you wouldn’t break even until 40 years, but solar panels last around 25 years on average. However, if you have your solar panels installed by an MCS-registered installer and they cost £4,500, you could save £220 a year including your SEG payments. That brings the payback time to around 20 years.

So although the initial outlay is slightly less when you install solar panels yourself, it’s much better to have them installed by an MCS-registered engineer so you can take advantage of the SEG payments.

Just like other major house improvement projects, some specific requirements must be met to allow for the installation of solar panels on commercial buildings. The main reason why these standards and regulations were established is to minimize the risk of the solar system becoming an issue or potential hazard in the unforeseeable future. So if you’re thinking about buying and fitting new solar panels, you’ll probably want to know whether or not you’ll require to submit a planning permission application for approval before you can proceed.

Fortunately, the installation of solar panels on commercial buildings may be “permitted development which mean you won’t have to apply to the Local Planning Authority for planning permission. There are, however, some important limits and conditions which must be put into consideration in order to benefit from these permitted development rights. Some of the limitations include:

• The solar panels must be installed on a wall or pitched roof that should project at a maximum of 200mm from the surface of the wall or roof slope.
• Equipment placed on a roof should not be within one metre of the external edge of that roof.
• Equipment mounted on a wall must not be within one metre of a junction of that wall with another wall or with the roof of the building
• If the equipment is on the roof of a building, the capacity for generation of electricity across the entire site must not be more than 1 megawatt.
• In the situation whereby the panels are installed on a flat roof, the highest part of the equipment should not exceed one metre above the highest part of the roof.

In general, obtaining a planning permission is very important and as such, you must discuss your position with your chosen installation company before you proceed.

There are a few trusted companies in the UK that make solar panels. While there are other solar thermal panels out there that are made by Chinese and American companies, we’ll focus on the brands with a longstanding presence in the UK since these are the panels MCS-registered solar companies are likely to recommend to you.

Viessmann, Worcester Bosch, Solar UK and Dimplex make some of the best solar thermal panels in the UK. Dimplex and Viessmann offer both flat plate and evacuated tube solar panels, while Solar UK only offers evacuated tubes. Worcester Bosch’s Greenskies range are all flat plate collectors. Viessmann’s panels come with a 5-year warranty, while Worcester Bosch and Dimplex offer extensive 10-year warranties. However, Solar UK offer a comprehensive 25-year warranty and guarantee that the panels will deliver the same level of performance for 25 years!

We’d recommend choosing evacuated tube solar thermal panels because they are the most efficient. While there won’t be much difference between evacuated tubes and flat plates in the summer, in the winter evacuated tubes are much better at taking heat from the sun than flat plates. Since our winters are long and cold with few daylight hours, we think it makes sense to go with evacuated tubes. However, if your priority is looks over maximising efficiency, you might want to choose flat plate collectors since they sit flat on the roof and look more like solar PV panels, whereas the evacuated tubes will stick out.

You shouldn’t need to maintain your solar panels much at all as long as there’s nothing piled up on top of the panels that could block out the sun. They are installed at an angle, so when it rains the water runs off them and gives them a clean. However, if this doesn’t quite cut it, you can spray them with a hose a few times a year.

If you want to connect solar panels to a battery, it’s likely that it’s because you want to make sure that you don’t waste any electricity when your solar panels are generating energy but you’re not around to use it. Batteries are particularly useful for homeowners that have solar panels but are out during daylight hours; with a solar battery system, your solar panels will feed the electricity they generate into the battery for you to use when you get home.

If you want to connect your solar panels to a battery, the best thing to do is to get in touch with an MCS-registered company who can talk you through your options. There are different size batteries and the size that’s suitable for you will depend on how much electricity you plan to store and how large your solar panel system is. Some of the top brands of battery storage system include Tesla, SunPower and SolarEdge. If you want to be able to take advantage of selling electricity back to the grid through the Smart Export Guarantee (SEG), it’s worth getting an MCS-registered company to install your battery for you, as you may not be eligible for payments if you connect your solar panels to a battery yourself.

You should also consider whether your solar panel system is a ‘storage ready’ solar system. Today, most systems will be, since battery storage is becoming much more common. This means that your solar panel system will have an inverter that can easily integrate a battery. If this is the case, you should be able to purchase the battery you want and follow the manufacturer’s instructions to install it.

However, it’s worth bearing in mind that electricity is extremely dangerous when handled incorrectly. If something goes wrong, you could electrocute yourself or cause a fire. If your solar panels and battery cause a fire, it’s unlikely that your home insurance company would pay out if you connect the battery yourself. That's why it’s best to ask a reputable installer with all the correct qualifications to connect your solar panels to a battery for you.

Solar PV panels work by converting sunlight into electricity. They’re made up of photovoltaic cells, which take in the sun’s rays and turn it into direct current (DC) electricity. The current is then channelled into an inverter, which converts it to alternating current (AC).

Once converted to AC, the electricity is ready to use. It’s fed through a meter and into your property’s consumer unit, and is automatically used to power appliances and heating systems. Your system will automatically switch between your solar electricity supply and the national grid, and export any solar electricity you don’t use to the national grid.