How Many Solar Panels Do I Need?

Posted on 21 March 2024 by The Solar Co

How Many Solar Panels Do I Need?

In today's world, where the conversation around sustainable living is more prominent than ever, solar energy emerges as the best possible option. It's not just an alternative; for many, it has become the primary source of power, revolutionising how we think about and consume energy. This shift towards solar is not only beneficial for the environment but also offers a pathway to energy independence and financial savings in the long run.

Whether you're a homeowner looking to reduce your carbon footprint or a renter curious about solar energy's potential, understanding the number of solar panels required for your home involves more than just a simple calculation. It's about assessing your energy needs, understanding the capabilities of solar technology, and aligning these with your environmental goals and financial considerations.

Types of Solar Panels and Their Efficiencies

Monocrystalline Solar Panels: These are made from a single, continuous crystal structure and are known for their high efficiency and sleek appearance. They typically have the highest efficiency rates, ranging from 15% to 20%, because they're made from the highest-grade silicon. Their efficiency comes at a higher price, but they're a great choice for homes with limited roof space due to their higher power output per square metre.

Polycrystalline Solar Panels: Constructed from multiple silicon crystals, polycrystalline panels have a distinctive blue hue and a somewhat lower efficiency rate than monocrystalline panels, usually between 13% and 16%. They are less expensive and offer a good balance between cost and performance, making them a popular choice for residential solar projects.

Thin-Film Solar Panels: These panels are made by depositing one or more thin layers of photovoltaic material on a substrate. They can be made from a variety of materials, including cadmium telluride (CdTe) and amorphous silicon (a-Si). Thin-film solar panels are the least efficient of the three main types, with efficiency rates generally between 10% and 13%. However, they are lightweight, flexible, and can be manufactured in large rolls, making them suitable for a wide range of applications, including unconventional surfaces.

The efficiency of a solar panel type is a critical factor because it determines how much of the sunlight that hits the panel can be converted into usable electricity. However, it's not the only factor to consider when determining how many panels you need. The available space for panels, your energy consumption, and the average sunlight hours in your location also play significant roles.

Factors Influencing Solar Panel Requirements

Several critical factors must be considered when calculating the number of solar panels needed:

Average Daily Sunlight Hours: Knowing the average number of sunlight hours your location receives each day is crucial. This figure varies significantly depending on geographical location, with some areas receiving more sunlight than others. The National Renewable Energy Laboratory (NREL) provides solar radiation maps and calculators that can help you determine this factor.

Solar Panel Wattage: The wattage of a solar panel indicates its power output under ideal conditions. Common residential solar panels range from 250 to 400 watts. Higher wattage panels can generate more electricity and may reduce the total number of panels needed.

Efficiency of Solar Panels: This refers to the percentage of sunlight that can be converted into usable electricity. As discussed previously, monocrystalline, polycrystalline, and thin-film panels have different efficiency rates, which will affect the overall system size.

Roof Space and Orientation: The available space on your roof and its orientation towards the sun play significant roles in determining how many panels can be installed and how effectively they will generate power.

Understanding the Quantity of Solar Panels Required for Your Home

When planning to transition to solar energy, it's essential to ascertain the number of solar panels necessary to meet your electricity needs adequately. An elementary formula to estimate your required solar system capacity is to divide your yearly kWh usage by 1200, yielding the system size in kilowatts (kW). While this formula provides a preliminary estimate, several other variables will influence the final calculation, such as roof space, ground mounting preferences, and budget constraints.

For locations with limited space, opting for high-efficiency panels is prudent to maximise production within a small area. Conversely, if space is abundant and budget is tight, less costly panels may be used to fill the area.

Performing the calculations yourself can give a rough estimate of your needs, but the examples we've drafted below will offer a clearer picture. It's advisable to engage with a solar installation expert to obtain a precise assessment tailored to your specific situation. In the interim, the following table serves as a useful guide.

Average Monthly Electric Bill

Solar System Size

Number of Panels (330W)

Estimated Space Needed


5 kW

16 Panels

312 sq. ft


10 kW

32 Panels

624 sq. ft


20 kW

61 Panels

1189 sq. ft


50 kW

157 Panels

3061 sq. ft


100 kW

438 Panels

8541 sq. ft


200 kW

556 Panels

10842 sq. ft


Embracing solar energy represents a pivotal shift towards a more sustainable and self-sufficient lifestyle. By harnessing the power of the sun, homeowners can significantly reduce their carbon footprint, decrease their reliance on fossil fuels, and enjoy considerable savings on energy costs over time. The journey to solar energy is unique for each household. The number of solar panels you need depends on various factors, including your energy consumption, the efficiency of the chosen panels, local sunlight conditions, and the available space for panels. By conducting a thorough analysis and consulting with professionals, you can design a solar system that perfectly matches your needs.


Can solar panels fully power a house?

Yes, solar panels can fully power a house, but this depends on several factors, including the household's energy consumption, the solar panel system's size and efficiency, and the location's average sunlight exposure.

What maintenance do solar panels require?

Solar panels require minimal maintenance to keep them operating efficiently. The main requirement is keeping the panels clean and free of debris, such as leaves or dust, which can block sunlight and reduce efficiency.

How long do solar panels last?

Solar panels are designed to be durable and long-lasting. Most manufacturers guarantee their panels will operate at or above a certain efficiency level for 25 to 30 years.

Are solar panels effective during winter?

Solar panels can still produce electricity during winter, although their output may decrease due to shorter daylight hours and potentially snow coverage.

Back to Blog