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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.

If you’re considering getting a solar thermal system, one of the first things that comes to mind is the possibility of the system functioning properly during the cold months. The short and simple answer to this question is yes, a solar thermal system works in the winter. However, the downside here is that it’ll be a lot less efficient when compared to how it operates during the warmer months or summer. As a result of this fact, you’ll likely need to rely more on your boiler, immersion heater or any other backup heating system during this period as your solar thermal system will fail to contribute as much as it does during the warmer months. So what exactly is the reason why solar thermal is less effective and less efficient in the winter period? Let’s have a look!

As you know, solar thermal system banks on the sun’s energy to heat the water for your home’s use. During the cold months or winter, the sunlight becomes a lot less available when compared to the warmer months, as a result, there’s less sunlight that’s available to be used for its solar energy. And even more so at the periods when the days are shorter or skies are clearly overcast.

Also having a great impact on a solar thermal system’s output is heavy snow. Flat plate collectors normally have the capacity to cope better during snowy conditions as the light that’s able to travel through the snow will heat up the absorber plate - thereby making the snow slide off more quickly. However, the case is contrary with evacuated tube collectors which possesses a form of vacuum insulation that’s crafted to minimize the loss of heat, meaning they can’t generate heat to melt and cause the snow to slide off in a similar way.

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.

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.

• The power of your solar panel system – there's no point buying a higher capacity battery if your system will never generate enough electricity to charge it
• How often you think you will need to charge your battery
• Your budget
• Whether you care about having the latest technology and a recognisable brand name

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.