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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.

It’s important to get the right size solar panel system for your commercial property. Solar panels are usually installed on pitched roofs, although they can be fitted on stands on the ground if you have some unused outdoor space. The more panels you install, the more power you’ll generate, but there’s no point buying more panels than you have space for.

Solar panel system sizes are measured in kW. 4-10kW solar panel systems are usually too big for domestic properties but are ideal for smaller commercial properties. Here’s an idea of how many panels and space you’ll need for a few different system sizes:

System size, Number of panels, Area required (approximate)

4kW, 16, 23m²

6kW, 24, 35m²

8kW, 32, 46m²

10kw, 40, 58m²

Bear in mind that solar panels can’t be less than 30cm away from a roof edge, so you’ll need more space than the area that the panels take up.

If your solar panels are mounted on your roof and you require a ladder to reach them we would always recommend you get a professional to do the work for your own safety.

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.

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.

1. After the installer’s measured up, given you an estimated output and recommended some systems for you, they’ll arrange date to come to your home to install the solar thermal panels. They’ll also let you know if any scaffolding will be required.
2. Next, they will start to fit the panels, or collectors, to your roof. Stainless steel brackets will be provided with the system and they will remove your roof tiles or slates to attach the brackets to the rafters. They’ll then replace the tiles and add waterproof flashing to ensure you don’t get any roof leaks, and add the frame.
3. If you’ve chosen evacuated tube solar thermal panels, the installer will bolt the heat transfer unit to the top of the frame but not install the tubes until nearer the end. This is because the tubes start to transfer heat to the exchanger immediately, and when everything is unconnected this could damage the unit.
4. If you don’t need a new boiler with your installation, a new dual coil water cylinder, pump and system control system will be fitted. It’s best in a loft or upper floor of your home.
5. A new thermal store or hot water tank that will store the heat provided by the solar system is much larger than a standard tank but it may fit in the spot of your old one. The installer will ensure that it’s connected to the mains cold water, your other heating source (such as a gas boiler or biomass boiler), immersion heater, temperature sensors and the solar collectors themselves.
6. Next they will install the pumping station, usually near the water tank. The expansion tank will be installed on the solar thermal loop, which is usually nearby. Its job is to prevent pressure changes that could damage the system.
7. You’ll get a heat generation meter which must be MCS-certified if you want to take advantage of the RHI, and any control equipment that comes with the system will be installed.
8. The installers will then bring the system to pressure by pumping the heat transfer liquid into the system up to a pressure of around 2 bar.
9. Finally, your MCS-registered installer will register your solar thermal system so you can apply for RHI payments of up to £525 per year.
So that’s the process of installing solar thermal panels. Remember – it's always best to use a professional to install any kind of renewable technology.

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.