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How Many Solar Panels And Batteries To Power A House?

Do you wish to know the number of solar panels and batteries sufficient for a house? Well, this is a frequently asked question in the solar world which would be very difficult to provide an accurate answer. This is basically down to the fact that all homes are unique with different sizes as well as amount of daily energy requirements. As a result, the number of solar panels and batteries needed would be unique to the house in question. However, we’ll consider the varying influencing factors that will go a long way to help calculate the number of panels and batteries needed to power a house.

First and foremost, let’s take a look at the solar panels. You’d have to start here by putting into consideration all household appliances that makes use of power in the house to get a good idea of how many that’ll be needed.

• How Many Watts Is Being Used In The House On A Daily Basis?

To determine this, 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.

• What Is The Number Of The Peak Sunlight Hours At The House’s Location?

Having in mind that the solar panels only work when under direct sunlight, the first step to determine the peak sunlight hours. Once determined, you can then multiply the figure in hours by the house’s hourly energy usage and divide by the solar panel’s wattage.

Overall for a 1500 square foot house, the number of solar panels that’ll be required should fall around 15 to 18.

Meanwhile for batteries, there are also some factors to be considered to determine the number of batteries that is required to power a house. These factors include the house’s power or electricity usage, the period of time in which the battery will be used as well as the battery’ specifications.

Solar panels provide an alternative to paying expensive National Grid energy rates, so primarily their first major benefit is helping to reduce bills. Solar PV panels will produce free electricity, whilst solar thermal panels generate heat for hot water and space heating. There are also payment incentives known as the Feed-in Tariff scheme (FITs) (for solar PV) and the Renewable Heat Incentive (for solar thermal) which guarantee a tax-free income for 20 years.

There are a few factors that will determine whether it’s worth getting a solar battery. They involve how much electricity you use, how often you’re at home and whether you receive any export payments.

To work out whether it’s worth getting a solar battery, you need to work out how much of the electricity you generate you’re using already. If you’re able to run all your appliances during the day while your solar panels generate electricity, then it sounds like you’re already using your electricity well. It might not be worth you getting a solar battery in this case.

However, if you’re not at home for a lot of the day, then you’ll be missing out on the electricity your panels are generating while the sun’s shining. If you install a solar battery system, you can store the electricity that your panels generate in the battery and use it when you get home. This will help you cut your electricity bills even further.

You’ll also need to consider whether you’re getting paid to export your electricity. If you’re on the Feed-in Tariff scheme (FITs) or receive payments from the Smart Export Guarantee (SEG), you’ll get paid for every unit of electricity you export to the National Grid. Before you decide whether it’s worth getting a solar battery, you’ll need to weigh up whether you’d be better off carrying on exporting your unused electricity rather than storing it to use yourself. If you’re unsure, visit the Energy Saving Trust’s website or speak to an MCS-registered installer who will be able to help you work out which is more cost-effective.

Not only will you reduce your electricity bill by generating your own electricity with solar panels, but you can also earn money through the SEG which is offered by large energy suppliers. They’ll pay you for the electricity you export back to the grid. You’ll also reduce your carbon footprint, lessening your impact on the environment.

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.

How much energy a solar panel produces depends on its manufacturer and exposure to the sun. A good-quality solar panel typically has a power output of about 300 watts per hour, but this can vary from about 240 to 360 watts. How much energy your solar panel will produce per day depends on how many hours of unshaded daylight it’s exposed to.

Here’s an idea of how much energy you could expect a large commercial solar panel installation to produce in a year.

Solar panel system size, No. of solar panels, Annual electricity output

11kW, 44, 9,350kW

20kW, 80, 17,000kW

30kW, 120, 25,500kW

40kW, 160, 34,000kW

50kW, 200, 42,500kW

No – solar thermal doesn’t generate electricity. Unlike solar PV, solar thermal panels harness the sun’s energy and convert it into heat which is then transferred into your home.

You can have evacuated tube solar thermal panels or flat plate collectors; evacuated tubes are thought to be more efficient that flat plate collectors. They both work by using the sun’s rays to heat a transfer fluid, usually made from water and a type of antifreeze, which is pumped to a heat exchanger inside a water tank in your home. The heat from the exchanger heats the water inside your tank, then when the liquid releases its heat it’s transferred back to the collectors to start the whole process again.

You’ll need to use your solar thermal panel system with a boiler, collector or immersion heater. This is so that the water can be stored and used for your hot water and heating, and also because in the UK, people generally need to rely on another source of heating in the winter. There are fewer sunlight hours in the winter months, so it’s not often possible for solar thermal panels to generate enough heat from the sun to get your water up to temperature.

Whatever the time of year it is, you might want to heat the water up further than your solar panels can manage. That’s why you’ll still need a form of traditional hot water heating, but you should see savings on your energy bills. If you’re currently using natural gas, you can expect savings of around £60 per year on your fuel bills, while if you’re using LPG it could be as high as £100 pr year

It’s vital to purchase a solar panel system that suits your property. If you’re investing in a solar panel system, it makes the most financial sense to get the biggest one possible. However, whether you can do this or not depends on budget and space.

Here’s an idea of how much roof or ground space you’ll need to install a few different sizes of commercial solar panel system.

Solar panel system size, No. of solar panels, Approximate area required

11kW, 44, 64m²

20kW, 80, 116m²

30kW, 120, 173m²

40kW, 160, 231m²

50kW, 200, 288m²