How many solar panels for a house: calculate in 3 steps

Are you wondering how many solar panels you need for a house? Solar power is a great idea for your home, but knowing how many panels you need isn’t always obvious. There are quite a few things to consider, such as your electricity consumption, the size of your roof, and even where you live. This guide is here to help you see things more clearly. We’ll look together at how to calculate all this, so you can make the right choice for your solar installation.

Key Points

To know how many solar panels you need for a house, you first need to know your annual electricity consumption. Look at your bills, it helps a lot.
The power of the solar panels, called peak power (kWp), is an important element. It determines the amount of energy your panels can produce.
Calling on a qualified professional (RGE) for a feasibility study is an essential step. They will be able to give you precise advice tailored to your situation.
The orientation and inclination of your panels on the roof are very important to capture as much sun as possible and produce more energy.
There are financial aids and electricity buy-back tariffs that can make your solar project more profitable. Find out about these schemes.

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Assess the energy consumption of your home

It is essential to accurately assess the energy consumption of your home before considering the installation of solar panels. This step will allow you to correctly size your installation and optimise your investment. An accurate assessment will help you determine the number of panels needed to cover your needs and maximise energy savings.

Analyse your annual electricity bill

The first step is to carefully examine your electricity bills over a full year. This analysis will give you an overview of your total energy consumption in kWh. Identify the months when your consumption is highest, which may indicate greater heating or air conditioning needs. If you don’t yet have a year’s history, you can use an online consumption simulator to get an estimate.

Calculate the daily consumption of appliances

To refine your assessment, it is useful to calculate the daily consumption of your main electrical appliances. Here’s a simple method:

Identify the most energy-intensive appliances (heating, water heater, air conditioning, etc.).
Estimate the number of hours of daily use of each appliance.
Multiply the power of the appliance (in watts) by the number of hours of use, then divide by 1000 to get the consumption in kWh per day.
Add up the consumption of all appliances to get an estimate of your total daily consumption.

It is important to note that this method provides an estimate. Actual consumption may vary depending on your habits and weather conditions.

Determine the specific needs of your house

Several factors influence the energy consumption of a house. It is essential to take them into account for a precise sizing of your solar installation. These factors include:

The living area: A larger house will require more energy for heating and air conditioning. For a house of 150 m², the consumption will be higher than a house of 100 m².
Insulation: Good insulation reduces heat loss in winter and keeps you cool in summer, thus reducing energy consumption. A poorly insulated house will have higher consumption.
The number of occupants: The more occupants there are, the greater the consumption of hot water and electricity will be.
Consumption habits: Your daily habits (heating temperature, use of appliances, etc.) have a significant impact on your consumption.

By taking these elements into account, you will be better able to assess your actual energy needs and size your solar installation optimally. Don’t hesitate to call on an RGE professional for a precise feasibility study.

Understand the factors influencing the number of solar panels

It is essential to understand the different factors that influence the number of solar panels needed for your home. Several elements come into play, ranging from the available surface area on your roof to the power of the photovoltaic panels you choose. A precise assessment of these factors will allow you to optimise your installation and maximise your solar energy production.

The impact of living area on the installation

The living area of your house has a direct impact on your overall energy consumption. The larger your house, the greater your electricity needs. Therefore, a larger living area will require a greater number of solar panels to cover these needs. It is therefore important to accurately assess the area of your house in order to correctly size your solar installation. You must also take into account the elements of roofing, such as a chimney or windows, as they can reduce the surface area available for solar installation.

The importance of peak power (kWp)

The peak power, expressed in kilowatt-peak (kWp), represents the maximum power that a solar panel can produce under optimal conditions. This value is crucial for calculating the number of panels needed. The higher the peak power of a panel, the fewer panels you will need to achieve your energy production goal. It is therefore important to compare the different options available on the market and choose panels with a peak power adapted to your needs and your budget. For a quality solar installation, it is important to choose the power of the panels carefully.

The technical specificities of photovoltaic panels

In addition to peak power, other technical specificities of photovoltaic panels can influence the number of panels needed. The panel’s efficiency, its lifespan, and its price are all factors to consider. A panel with a high efficiency will produce more electricity than a panel with a lower efficiency, for the same surface area. Similarly, the lifespan of the panel is an important element to consider when assessing the long-term profitability of your installation. Finally, the price of the panel is a determining factor in the choice of your equipment.

It is important to note that the sizing of a solar installation is a complex process that requires technical expertise. It is therefore strongly recommended to call on an RGE (Reconnu Garant de l’Environnement – Recognised Guarantor of the Environment) professional to carry out a feasibility study and advise you on the choice of panels and the sizing of your installation. This professional will also be able to assist you with the administrative procedures and help you benefit from the financial aid available. The photovoltaic future is promising and it is important to be well informed.

Here are some elements to consider when choosing your panels:

The power of the panel
The efficiency of the panel
The lifespan of the panel
The price of the panel

Finally, it is important to take into account the sunshine in your region. The annual sunshine has a direct impact on the amount of solar energy captured by the panels. The overall efficiency of the system will therefore be sensitive to the geographical area in which you live. If your roof is well sunny, the yield will be optimal. During the study of your project, the meteorological data of annual sunshine must be analysed. It is important to properly assess the energy consumption of your home.

Carry out a precise solar sizing

Solar sizing is a bit like choosing the right size of clothes: it has to fit your needs. It’s a crucial step to ensure your solar installation works optimally and brings you the expected benefits. We can’t just make approximations, we need a methodical and rigorous approach.

The feasibility study by an RGE professional

The first step, and probably the most important, is to have a feasibility study carried out by an RGE (Reconnu Garant de l’Environnement – Recognised Guarantor of the Environment) professional. This isn’t just a quick glance, it’s an in-depth analysis of your specific situation. The professional will assess several factors, such as your energy consumption, the orientation and inclination of your roof, any shaded areas, and of course, your budget. This study determines the ideal size of your installation and ensures that it is technically feasible.

The optimal orientation and inclination of the panels

The orientation and inclination of the solar panels are key elements to maximise their efficiency. In France, a south-facing orientation is generally considered optimal, as it allows you to capture the maximum amount of solar radiation throughout the day. The ideal inclination depends on your latitude, but is often between 30 and 45 degrees. However, you must take into account the specificities of your house and your region. A slight deviation from the ideal orientation can be compensated for by a greater inclination, and vice versa. It is therefore important to have a precise study carried out to determine the optimal configuration for your situation. For a house of 150 m², the orientation of the roof must be carefully studied.

Maximise the efficiency of your installation

Maximising the efficiency of your solar installation is a bit like optimising the performance of a racing car: every detail counts. Here are some points to consider:

Choose quality panels: Opt for high-performance photovoltaic panels that are adapted to your budget. Monocrystalline panels are generally more efficient than polycrystalline panels, but they are also more expensive.
Use a high-performance inverter: The inverter is the brain of your solar installation. It converts the direct current produced by the panels into alternating current that can be used by your electrical appliances. A high-performance inverter minimises energy losses and optimises the efficiency of your installation.
Slightly oversize your installation: If you plan to increase your energy consumption in the future (for example, by buying an electric car or installing a heat pump), it may be wise to slightly oversize your solar installation. This will allow you to cover your future needs without having to add panels later. For an autonomous installation, the battery must be properly sized.

The precise sizing of your solar installation is an investment that can save you a lot of money in the long term. By calling on an RGE professional and taking into account all the relevant factors, you can be sure of obtaining a high-performance installation that is adapted to your needs.

Don’t forget to consider the cost of a solar installation when planning.

The different types of solar systems for your house

There are a variety of solar systems designed to meet the specific needs of each home. From heating water to producing electricity, to air conditioning, solar energy offers diversified and adapted solutions. It is important to understand the different options available in order to choose the most appropriate system for your house.

Active solar heating and its components

Active solar heating uses solar thermal collectors to capture heat from the sun. This heat is then transferred to a heat transfer fluid, which transports it to a distribution system in the house. This system may include a storage tank for later use. Active systems are more efficient at heating water and air, but require mechanical and electrical components to operate.

Solar thermal collectors: They absorb solar radiation and convert it into heat.
Heat transfer fluid: It transports heat from the collectors to the distribution system.
Storage tank: It allows heat to be stored for later use, even in the absence of sunshine.

Passive solar heating and building design

Passive solar heating relies on the very design of the building to capture, store and distribute solar heat. This involves strategic orientation of windows, the use of materials with high thermal inertia and effective insulation. The objective is to maximise solar gain in winter and minimise overheating in summer. It is a more integrated approach and less dependent on complex technologies.

Passive solar heating is a design approach that aims to reduce reliance on traditional heating systems. It is a sustainable and economical solution that can improve the thermal comfort of your house.

Innovative solar air conditioning systems

Solar air conditioning is an emerging technology that uses solar energy to power cooling systems. These systems can be based on absorption, desorption cycles or on mechanical systems powered by photovoltaic solar panels. Although less common than solar heating, solar air conditioning offers an ecological alternative to traditional air conditioners. It is important to note that the installation of photovoltaic solar panels can be coupled with an air conditioning system for a complete energy solution.

Absorption chillers: They use solar heat to power a cooling cycle.
Desiccant air conditioners: They use absorbent materials to dehumidify the air, reducing the cooling load.
Solar-powered mechanical systems: They use electricity produced by solar panels to power a traditional air conditioner.

In summary, the choice of the most suitable solar system for your house will depend on your specific needs, your budget and the design of your building. A thorough study and the advice of a professional are essential to make the right choice and optimise solar energy from your installation.

Consider the financial aspects of solar installation

Investing in solar panels represents a significant expense, but it is essential to consider all the financial aspects to assess its relevance. Several elements come into play, ranging from the initial cost of the installation to the financial aid available, to the long-term return on investment. An in-depth analysis will allow you to make an informed decision.

Estimate the cost of an installation for a house

The cost of a solar installation for a house varies considerably depending on several factors. The power of the installation, expressed in kilowatt-peak (kWp), is a determining element. The higher the power, the higher the cost will be. The type of solar panels chosen (monocrystalline, polycrystalline or thin-film) also influences the price. Finally, the complexity of the installation, linked to the configuration of your roof and accessibility, can impact the cost of labour.

On average, the cost of a solar installation can be estimated at between €8,000 and €15,000 for a detached house, but this figure can vary considerably. It is therefore crucial to request several quotes from qualified professionals to obtain an accurate estimate adapted to your situation.

Price variations according to characteristics

Several characteristics can influence the price of a solar installation. The type of solar panels, as mentioned previously, is an important factor. Monocrystalline panels, offering better efficiency, are generally more expensive than polycrystalline panels. The brand and quality of the solar panels also play a role. A higher quality inverter, ensuring efficient conversion of direct current to alternating current, can also increase the initial cost, but improve long-term performance. The complexity of the installation, especially if it requires roof reinforcement work or specific adaptations, can also lead to additional costs. It is wise to choose an air conditioning system adapted to the area to be cooled.

Financial aid and return on investment

Fortunately, there are several financial aids to reduce the cost of a solar installation. The government offers schemes such as the self-consumption bonus, which encourages the production and consumption of your own electricity. Regional and local aid may also be available. It is important to find out about the eligibility conditions and the steps to be taken to benefit from this aid.

The return on investment of a solar installation depends on several factors, including the initial cost, electricity production, the price of electricity and the financial aid received. In general, it is estimated that the return on investment is between 8 and 15 years, but this can vary considerably depending on your situation.

To maximise the profitability of your installation, it is essential to properly size your installation according to your energy needs, optimise the orientation and inclination of the solar panels, and choose a qualified installer. Don’t forget that the profitability of a solar installation is influenced by many factors. In addition, the property value of a house equipped with solar panels is often higher. Thus, you can benefit from a return on investment at the time of sale of the property. It is wise to obtain detailed quotes from several solar installers to obtain a precise estimate of the price of the installation adapted to your house.

The administrative procedures for the installation of solar panels

The installation of solar panels involves following certain administrative procedures. These procedures vary depending on the type of housing and the nature of the work. It is therefore important to find out as much as possible before starting your project to avoid any inconvenience.

The necessary authorisations for detached houses

For a detached house, the installation of solar panels generally requires a prior declaration of works. This declaration must be filed with the town hall of your municipality. It allows the town hall to verify that your project complies with the town planning regulations in force. The processing time is generally one month. If the town hall does not respond within this period, your application is considered accepted.

It is strongly advised to consult the Local Town Planning Plan (PLU) of your municipality before submitting your declaration. This document contains the specific rules to be respected for the installation of solar panels, in particular with regard to the aesthetic aspect and the integration into the landscape.

It is important to note that in some cases, especially if your house is located in a protected area (classified site, protected sector), the agreement of the Architecte des Bâtiments de France (ABF) may be required. In this case, the processing time may be longer.

The requirements for collective housing

In collective housing, the installation of solar panels is subject to specific rules. It is imperative to obtain the agreement of the co-ownership before starting the work. This request must be placed on the agenda of the general meeting of co-owners.

It is also necessary to check the co-ownership regulations, which may contain specific clauses concerning the installation of solar panels. These clauses may relate to the aesthetic aspect, the location of the panels, or the distribution of the costs and benefits of the installation.

In addition to the agreement of the co-ownership, a prior declaration of works may be necessary, as for detached houses. It is therefore important to check with the town hall of your municipality.

The prior declaration of works at the town hall

The prior declaration of works is an administrative form that allows the town hall to check the conformity of your project with the town planning regulations. This form must be accompanied by several documents, such as:

A site plan of the land
A floor plan of existing and planned constructions
A cross-sectional plan of the land and the construction
A descriptive note of the works
Photographs of the current state of the land and constructions

It is possible to download the prior declaration of works form from the public service website or to collect it directly from the town hall. Once completed, the file must be submitted to the town hall in several copies (usually 4). The town hall will issue you with a receipt, which certifies receipt of your application. Don’t forget to declare your solar panels to be in compliance with the law.

In the event of non-compliance with the town planning regulations, the town hall may ask you to modify your project or even to remove the solar panels. It is therefore essential to find out as much as possible and to respect the administrative procedures in force. For an installation of solar panels in La Rochelle, the procedures may be specific due to the proximity of the ocean and local town planning regulations. Calling on a photovoltaic installer can help you manage these administrative aspects.

Optimise the efficiency of your solar system

To get the most out of your photovoltaic installation, it is essential to adopt a proactive approach to optimisation. This involves paying particular attention to maintenance, adopting innovative technologies and managing the energy produced efficiently. A well-maintained and optimised solar installation will allow you to maximise your energy production and reduce your dependence on the traditional electricity grid. It is important to note that many factors influence the profitability of a solar installation, such as the weather, the insulation of the house, the living area, the type of electrical equipment used, the installation conditions (exposure to the sun, orientation and inclination), the nominal power and the maintenance of the solar panels.

The importance of regular panel maintenance

Regular maintenance is crucial to maintain the optimal performance of your solar panels. Dust, leaves, bird droppings and other debris can significantly reduce the amount of sunlight reaching the photovoltaic cells. Regular cleaning, ideally twice a year, ensures that your panels are operating at their full capacity. It is recommended to use fresh water and a soft brush to avoid damaging the surface of the panels. To simplify the task, you can use a solar simulator to discover the optimal size of your solar installation, depending on your electricity consumption and the location of your home.

Technologies improving energy efficiency

Technological innovation plays a major role in improving the efficiency of solar systems. New generation inverters, for example, optimise the conversion of direct current to alternating current, thus reducing energy losses. Similarly, solar panels with high-efficiency cells capture a greater amount of sunlight, even in low-light conditions. The integration of energy storage systems, such as batteries, allows you to store the surplus energy produced during the day for later use, thus increasing self-consumption and reducing dependence on the grid.

The adoption of smart technologies, such as energy management systems, allows you to monitor and control energy production and consumption in real time, optimising the use of solar energy and reducing energy costs.

The role of the inverter in performance

The inverter is an essential component of your solar system, as it converts the direct current (DC) produced by the panels into alternating current (AC) that can be used by your electrical appliances. A high-performance inverter ensures efficient energy conversion, minimising losses and maximising the amount of electricity available for your house. There are different types of inverters, each with its own advantages and disadvantages. The choice of inverter should be based on the specificities of your installation and your energy needs. It is advisable to carry out a thermal assessment with a professional for a custom installation.

Here is a simplified comparative table of inverter types:

Inverter type	Advantages	Disadvantages
Central inverter	Lower initial cost	Sensitivity to shading, impacting overall production
Micro-inverters	Individual optimisation of panels, better resistance to shading	Higher initial cost
Hybrid inverters	Easy integration with storage batteries	Increased complexity, potentially higher cost

To maximise the profitability of your solar panels, it may be relevant to oversize your installation, especially if you are planning to buy new electrical equipment (EV car, heat pump, solar charging station, etc.).

Choosing the right installer for your photovoltaic project

Selecting a competent installer is a determining step for the success of your solar project. A qualified professional will ensure you an installation that complies with standards, optimal performance and long-term peace of mind. It is therefore essential not to neglect this step.

The importance of using an RGE professional

Using a Reconnu Garant de l’Environnement (RGE – Recognised Guarantor of the Environment) professional is more than just a recommendation: it is a guarantee of quality and competence. An RGE installer has undergone specific training and is committed to respecting strict quality criteria. In addition, the use of an RGE professional is often a sine qua non condition for benefiting from state financial aid.

Request several quotes for an informed choice

Don’t rush into the first quote that comes along. It is strongly advised to request several offers from different installers. This will allow you to compare prices, services offered and guarantees offered.

Here are some points to check when comparing quotes:

The details of the equipment offered (panels, inverter, etc.).
The cost of labour.
The guarantees offered (on the equipment and on the installation).
The installer’s references.

It is wise to obtain detailed quotes from several solar installers to obtain an accurate estimate of the price of the installation adapted to your specific situation. This approach will allow you to compare the different offers and select the one that best suits your requirements and your budget.

The selection criteria for a specialised company

Beyond RGE certification and the comparison of quotes, other criteria can help you choose the company best suited to your project.

Experience: Choose a company with solid experience in the field of photovoltaics. You can consult customer reviews and ask for references.
Proximity: Choosing a local company makes it easier to monitor the site and intervene if necessary. You can find qualified tradesmen in your department in just a few clicks.
The quality of the equipment: Find out about the brand and quality of the solar panels offered. High-performance and durable equipment will ensure you better performance and greater longevity of your installation. Solencia, for example, specialises in photovoltaic projects and offers complete services for solar energy solutions.
After-sales service: Make sure that the company offers a responsive and efficient after-sales service. Good follow-up will allow you to quickly resolve any problems encountered.

The environmental impact and energy savings

Reduce your carbon footprint with solar power

Adopting solar panels is a concrete step towards reducing your environmental impact. By using solar energy, a renewable and clean resource, you reduce your dependence on fossil fuels, the main sources of greenhouse gas emissions. Solar energy is an effective solution to contribute to the fight against global warming.

The installation of solar panels allows you to reduce your carbon footprint and actively participate in the energy transition. It is a sustainable investment for the environment and for future generations.

The long-term benefits on energy bills

Beyond the ecological aspect, the installation of solar panels offers considerable financial advantages in the long term. Although the initial investment may seem significant, the production of solar electricity allows you to significantly reduce your energy bills. In addition, in the context of self-consumption, you can resell the surplus electricity produced, thus generating additional income. It is important to note that solar panels offer an excellent starting point for beginners.

Contribute to the energy transition

By choosing solar energy, you are actively participating in the energy transition, a major issue of our time. This transition aims to gradually replace fossil fuels with renewable energy sources that are more respectful of the environment. Solar energy, thanks to its abundance and availability, plays an essential role in this transition. In addition, the installation of a photovoltaic greenhouse can be a sustainable solution for agriculture.

Here are some concrete actions you can take to support the energy transition:

Give preference to green electricity suppliers.
Invest in energy-efficient equipment.
Adopt responsible consumption habits.

Together, we can build a more sustainable energy future.

Adapt the installation to the size of your house

It is essential to adapt your solar installation to the size of your house to optimise its efficiency and make your investment profitable. The surface area of your home directly influences the number of panels needed to cover your energy needs. A precise assessment is therefore essential.

Number of panels for a 100 m² house

For a 100 m² house, the estimation of the number of solar panels depends on several factors, including your annual energy consumption and the power of the panels chosen. In general, a house of this size requires an installation of 3 kWp to 5 kWp. Knowing that a standard solar panel has a power of about 300 to 400 Wp, it would take between 8 and 17 panels. It is important to note that these figures are indicative and that a personalised study is recommended to determine the exact number of panels needed. Don’t hesitate to use a solar simulator to get a more accurate estimate.

Estimate for a 150 m² house

A 150 m² house will naturally have greater energy needs than a 100 m² house. For this type of surface area, an installation of 5 kWp to 7.5 kWp is often recommended. This corresponds to approximately 13 to 25 solar panels, depending on their power. It is crucial to take into account the insulation of the house, the number of occupants and consumption habits to refine this estimate. Good insulation can significantly reduce the number of panels needed.

Calculation for specific surfaces

For specific surfaces, the calculation of the number of solar panels must be adapted. Here is a general approach:

Assess your annual consumption in kWh.
Determine the peak power (kWp) needed to cover this consumption.
Choose solar panels with a specific power (for example, 400 Wp).
Divide the peak power needed by the power of a panel to get the number of panels required.

It is strongly advised to have a feasibility study carried out by an RGE professional. This study will take into account the orientation of your roof, its inclination, any shaded areas and the specificities of your energy consumption. This will allow you to obtain an accurate estimate and optimise the performance of your installation. Don’t forget to consider the dimensions of a solar panel to plan the installation.

In conclusion, adapting the installation to the size of your house is a crucial step to maximise the benefits of solar energy. A precise assessment of your needs and a personalised study are essential for optimal sizing. Think about the size of the installation for a 150m2 house.

For your heating or air conditioning system to work at its best, it is crucial that it is well suited to the size of your home. An appliance that is too small will not heat enough, while one that is too large will consume unnecessarily. Find out how to choose the right size for your house by visiting our website now!

In summary: solar energy, a choice that pays off

Calculating the number of solar panels for your house isn’t just a matter of numbers. It’s above all a step towards a more autonomous and environmentally friendly house. By following these steps, you can have a clear idea of what you need. Don’t forget that a professional can help you refine all this. The initial investment may seem significant, but the long-term savings and the positive impact on the planet are very real. So, ready to go solar?