Before you go all in and switch to solar panel power, you’ll need to consider the electricity demands of your household, and then determine how many solar panels you will need in order to meet that demand.
The cost of a solar panel installation is highly dependent on this critical factor, it is imperative to determine what your requirements are in order to ensure that your solar panel power installation will be efficient and provide a sound investment.
Determining Your Solar Panel Power Requirements
The first thing you must do when working out your solar panel power requirements is determining the annual power consumption of your household or property. To do this, just take a look at your latest electricity bill and find the total kWh consumed figure.
If it’s a monthly figure, multiply it by 12. If it is a bi-monthly figure, multiply by 6. This will give you a good indication of your annual electricity consumption. (if the figure you take is from the Summer months, you may need to add a little on as we all use more electricity in Winter.) From this, you can then determine how many panels you will require:
| Consumption | Consumption | Panels Required (390w) |
|---|---|---|
| Low | < 2000 kWh | 3 - 5 |
| Medium - low | 2000 - 4000 kWh | 5 - 10 |
| Medium | 4000 - 6000 kWh | 10 - 15 |
| Medium - High | 6000 - 8000 kWh | 15 - 20 |
| High | 8000 - 10000 kWh | 20 - 25 |
Other Considerations
While crucial, there’s more to determining how many panels you need than simply the power requirements. Let’s break it down:
Performance and Quality of Panels
When considering purchasing solar panels, you must consider the performance and wattage. While initially more expensive, higher quality panels come with greater efficiency and performance, producing more energy and, therefore, reducing the number of panels that you will require - and reducing the payback period of your investment.
Historically solar panel power installations utilised Amorphous type arrays; these have now been discontinued across the industry due to a lower efficiency and lifespan compared to modern alternatives. The latest solar panels are made with Mono- and Poly-Crystalline cells.
Installed Capacity
This calculation of solar panel power ties in with the electricity demand calculation carried out at the start of this article. The aim here is to determine the total power output of your proposed array and ensure it meets your demands.
First, find the peak power output of a single panel, usually measured in Watts (W). Next, multiply this by the number of panels in your proposed array.
An average efficient solar panel power output is in the region of 350W. So, if you have seven panels, you’re looking at 2450W annual output.
An important consideration here is that the manufacturers’ stated peak power output is normally an example based on the panel being installed in optimal conditions with maximum sunlight availability, operating temperature, orientation, etc. Therefore, it is good practice to assume that you’re unlikely to obtain this stated peak power and plan accordingly.
Roof Orientation
The solar panel power efficiency is also greatly influenced by the quality of installation. A good quality installation will ensure that the panels are positioned facing south (in the Northern hemisphere) and at the best angle of inclination. Poor positioning will result in reduced solar panel efficiency and be less likely to meet the electricity demands of your property.
Geographical Location
Finally, we come to where you’re located in the world. Imagine shining a torch or small lamp horizontally onto a globe. The light would be the most intense at the area perpendicular with the light. In the real-world, this is the equator - where the sun is directly overhead.
As you move away from the equator into the northern or southern hemispheres, the intensity of the sun’s rays become weakened. This results in a loss of efficiency when it comes to solar panel power. Don’t worry though, there is still sufficient light in the UK for a solar panel to run efficiently. However, you may not yield 100% of the stated power from the manufacturer and, therefore, may have to account for this when you decide how many panels to put into your array.
Can a house run 100% on solar power?
If you’re keen to switch to solar, you may be wondering, and rely solely on the free energy that you harvest from the sun every day.
Unfortunately, we must burst your bubble, as this isn’t always achievable. Here’s why:
1. It’s not daytime, all the time
Obviously if you are using electricity at night, or in the hours of darkness…you won’t be able to use solar panel power (there is a solution to this though).
2. Sometimes it’s overcast
While your solar panels will continue to generate electricity on cloudy days, they run at their best when the sun is bright. So, on rainy winter days where the sun appears to have taken a holiday, you may end up having to fall back on the power from the grid.
3. Our needs are too great
Often our daily habits mean that our consumption of electricity demands a plentiful supply. So, if you want a greater chance of being less reliant on the national grid, it’s a good idea to review your power needs and cut out or reduce what isn’t essential.
For example, you could try turning appliances off rather than leaving on standby. Other examples include lowering the temperature of your boiler and thermostat, filling the kettle with only as much water as you need and boiling less frequently, or switching the TV off if no-ones watching it.
The alternative is to make sure that you thoroughly calculate how many panels you will need based on the calculations above, overcompensate for the demand when specifying the panels…and make sure you opt for high-quality panels, installed by a professional. Begin to calculate your cost for installing solar here.
Salient Solar Panel Points
When seriously considering going down the solar panel power route, it’s crucial to determine what your goal is, and understand what your current electricity demands are.
You should also make sure you understand what may influence or affect the amount of electricity you will be able to generate. Opting for solar panel power is an investment - so make sure it’s a sound one! Contact us today for more information or check out our solar page.
