What is the yield of a solar panel? Truth and calculation, yield of a solar panel: explanations and calculation | Hellio

Yield of solar panels: how to calculate it


Loss of yield can also be explained by a shady On the surface of your roof. By pushing, some branches of trees can for example hinder the sun, when this was not the case at the time of the pose. So remember to check this element very regularly.

What is the yield of a solar panel ? Truth and calculation

When you install photovoltaic panels at home, a question is quickly asked: what will be the performance of these solar panels ? It is indeed essential to know how much electricity they will create, in order to calculate the financial profitability of your project. The most commonly installed panels have a yield between 13 % and 24 %, but this yield can drop to less than 10 % for solar panels with amorphous silicon. Discover all the explanations and details of these calculations.

Install solar panels with Engie My Power
Save money on your electricity bill


  1. What is the yield of a solar panel ?
  2. Average yield and amount of energy observed
  3. The performance fluctuations of solar panels
  4. How to calculate the yield of a solar panel ?
  5. How to improve the performance of its solar installation ?
  6. What is the annual production of a solar panel ?

What is the yield of a solar panel ?

THE yield of a solar panel corresponds to the amount of light energy transformed into electricity compared to the amount of energy which is entered into the system. He expresses himself as a percentage.

The more yield an installation is high, the more the photovoltaic project is profitable. Indeed, this means that the losses are less and that you will produce more electricity for the same amount of sun stored.

Average yield and amount of energy observed

What is the average yield of a solar panel ?

A number of factors are to be taken into account to know the performance of your solar panels. However, some averages are observed according to the type of panels installed. The theoretical limit of yield of a panel is 31 %.

With some solar panels with amorphous silicon, the yield is generally between 6 and 9 %, which is quite low.

THE polycrystalline panels have a yield between 13 % and 18 %. This is the most commonly used panel type.

Finally, with Monocrystalline solar panels, yield can be 16 % to 24 %. They are therefore the most efficient on the market. This type of panel is generally more expensive than the others, but its profitability is for example twice higher than amorphous silicon panels: it therefore takes a surface half as important to produce the same quantity of electricity.

How much energy produces an average photovoltaic panel ?

A solar panel measures on average 1.6 m2. If its yield is 18 %, it transforms 18 % of solar energy into electrical energy. If the energy received is 1000 W/m2, the panel produced:

18 % x 1.6 x 1000 = 288 WC. PTo obtain a 3 kWc installation, so it takes a dozen solar panels. For a 100 m2 house, this is the number that is often advised.

The performance fluctuations of solar panels

The criteria that influence the performance of a photovoltaic panel

Many factors can influence the yield of a solar panel. Indeed, it can vary depending on:

  • There technology Used: monocrystalline, polycrystalline or amorphous panels do not have the same yield.
  • There power of your solar panels. This is expressed in KWC (Kilowatt-Rêête).
  • There geographical area implantation: all regions are unfortunately not sunny in the same way all year round. Photovoltaic production will therefore be different. Too high temperature can also negatively influence your performance
  • L’orientation and thetilt of your panels: a southern orientation and an inclination at 30 ° are optimal.
  • THE shaded areas around your installation (trees, buildings), which could reduce your production.
  • The different elements of Your solar kit : inverter or microphone, cables, etc. The more good quality you choose, the more likely you are to get a good performance.

How to explain yield losses ?

Unfortunately it may happen that your solar panels lose yield. Several factors can explain this.

External factors

One of the most frequent causes is dirtiness present on the surface of your panels. Dust, pollution, sand, bird droppings: rain is generally enough to sweep them, but sometimes, additional cleaning is necessary. Be careful not to damage them during the operation: use only soft rags and water to ambient temperature. Do not use any detergent. If the panels are not accessible with a telescopic broom, call a professional so as not to risk the slightest accident by going on your roof. Cleaning the solar panels can save you until 15 % electricity production. If after the operation, you do not notice any increase, the problem certainly comes from elsewhere.

Loss of yield can also be explained by a shady On the surface of your roof. By pushing, some branches of trees can for example hinder the sun, when this was not the case at the time of the pose. So remember to check this element very regularly.

Finally, the too hot harm the performance of photovoltaic panels. Indeed, beyond 25 ° C, it decreases. If this is the case with you, you should not particularly worry about the drop in yield of your panels.

Internal factors

Some causes can also be due to the panels themselves. Over time, it is not impossible that one of the elements that compose them deteriorates. This can for example be the case with protective glass. After a while, it may no longer allow as many solar rays as at the beginning, which greatly reduces electricity production.

If you observe brown spots on your modules, even after cleaning them, it may be a sign that Photovoltaic cells have grilled. The panel can then continue to operate, but produces less electricity.

Finally, it is possible to observe a electrical degradation installation. Do not worry: this case is observed in the vast majority of time on old installations. At the time, the cable connecting the inverter to the modules was not always put to the ground, which can cause high tensions and leakage currents. If you notice such a thing at home, have your installation checked by an authorized professional.

How to calculate the yield of a solar panel ?

The yield of a panel is expressed in percentage. As explained previously, this is the amount of light energy transformed into electricity compared to the amount of energy that is entering the system. The formula is therefore as follows:

Yield = electrical power produced/solar power received.

The electric power produced is expressed in Watt-Rête. The solar power received corresponds to the surface in M2 multiplied by 1000.

For example, if a polycrystalline solar panel has an electrical power of 250 WC and an area of ​​1.5 m2, its yield is:

250/(1.5 x 1000) = 16.66 %.

In this example, we can realize that the yield of this panel is in the average of polycrystalline panels.

How to improve the performance of its solar installation ?

It is difficult to very significantly increase the yield of a solar installation. However, some tips can still help you.

First of all, remember to clean the surface of your panels very regularly, especially when it hasn’t liked it for some time. In winter, you must be vigilant to remove the snow. In autumn, it is the dead leaves that can have an impact on your performance.

You must also regularly check the shade possible that can be present on your roof. Indeed, solar panels located in the shade can in some cases completely destroy your electricity production. So this is an element to check very regularly: it is not because there was no shadow at the time of their installation that it is always the case. Tree branches can for example have pushed after a few years. If you have the possibility, therefore prune these branches or the other elements that could alter your production.

Finally, we previously talked about the fact that solar panels are sensitive to high temperatures. Their yield decreases when the temperature exceeds 25 ° C. Know that a installation of over -prime of solar panels limits overheating. Indeed, this allows them not to be in contact directly with the roof. Thus, air circulates better.

A solar panel will therefore have a yield between 6 % and 24 % depending on many criteria: the type of panels, its orientation, its inclination, its geographic area of ​​location, etc. Be sure to install quality equipment if you don’t want to risk having a unpleasant surprise !

What is the annual production of a solar panel ?

Factors that influence solar production

The quantity of electricity produced annually by a solar panel depends on different factors. The most important are:

  • the power of the panel;
  • its orientation;
  • its inclination;
  • The sunshine rate of the region in which it is established;
  • its yield.

The more power, sunshine rate and yield are high and The more annual production is important. Regarding orientation and inclination, it is considered that production is maximum when the panel is placed south with a Angle from 30 to 45 °.

Calculate the annual production of a solar panel

Unfortunately, it is not possible to know precisely the Annual production of a solar panel based on the criteria that we have just stated. Indeed, the quantity of electricity produced depends on the quantity of solar rays which come into contact with your panel during the year. The weather therefore plays a decisive role, and it is not possible to predict it with certainty over such a long period. However, it is quite possible to Based on the observed averages for’obtain an estimate of annual production of your solar panels.

It is considered that in regions located in the north of France, a solar installation of 1 kWc produces on average 800 to 1,000 kWh every year. In the southeast, the average is rather between 1,200 and 1,400 kWh per year. Please note, if your installation is not south oriented, it is very likely that the annual production of your solar panels is lower.

To obtain a precise estimate according to your personal situation, you can call on an advisor Engie Mypower. By studying your project, he will be able to carry out a precise and detailed estimate.

A solar panel will therefore have a yield between 6 % and 24 % depending on many criteria: the type of panels, its orientation, its inclination, its geographic area of ​​location, etc. Be sure to install quality equipment if you don’t want to risk having a unpleasant surprise !

How to calculate the profitability of a solar panel ?

Many factors are to be taken into account to calculate the profitability of a solar installation : type of panels, power, consumption of the home, inclination, orientation, self -consumption, resale, etc. On average, we consider that the installation of photovoltaic panels is profitable at the end fifteen years. You can request the realization of a free personalized study in order to learn more about the profitability that you can hope for at home.

Is the photovoltaics profitable ?

Yes, Installing solar panels at home is profitable. The price of the panels has also dropped in recent years, which makes them more accessible to the purchase. You can optimize your profitability by calculating the savings made thanks to self -consumption or resale to EDF Buy. A certain number of aids and bonuses can also be given to you for your project, so ask as much as possible.

How to optimize its solar production ?

To optimize your solar production, choose panels, an inverter and quality cables. Try to have a southern orientation, an inclination at 30 ° and little shade. Maintain them by cleaning them: clean panels produce more. Finally, maintain your installation regularly.

Yield of solar panels: how to calculate it ?

Solar panel yield

The installation of solar panels is an attractive solution to produce your own electricity in self -consumption and at the same time make a gesture for the planet. However, the profitability of the project depends on the quantity of solar energy that the panels will be able to convert to electricity. How to calculate the yield of a solar panel, and especially how to optimize it effectively ? Our experts reveal the essentials to know to make your photovoltaic installation a complete success in 2023, and save in the long term.

Produce your own photovoltaic electricity with Helio

  • Definition of yield
  • How to maximize the yield of a panel ?
  • Calculation of production capacity
  • Some hazards to take into account

Reminder on the types of solar panels

The term “solar panel” in fact brings together several technologies and functions. All exploit the energy emanating from the sun (in the form of light or heat), but not for the same uses.

  • A photovoltaic solar panel produces electricity. This feeds the house or building circuit (we also find it more and more in industry, in parking lots, etc.)). Photovoltaic cells, generally composed of silicon, capture electrons and generate a direct current. Then, a inverter transforms it into alternating current, which can be consumed in the accommodation or reinjected into the electrical network.
  • A solar thermal panel produces heat. We find in particular individual solar water heaters (CESI). These facilities rarely be enough to cover 100 % of the needs of a home, which is why they are associated with another system such as a heat pump. Another fashionable equipment, and encouraged by bonuses: the combined solar system. The SSC is used for both heating and production of domestic hot water (DHW).
  • A hybrid solar panel combines the two uses: heat and electricity, thanks to small hot water pipes installed under the photovoltaic panels. This technology also has the interest of increasing the life of the product.

Today, solar thermal panels (water heaters and combined solar system) and hybrid are much more subsidized than their photovoltaic counterparts: Maprimerénov ‘, heat funds, energy savings certificates (EEC). Indeed, the public authorities want above all eradicate fossil energy heating devices, for the benefit of renewable energies (ENR). On the photovoltaic side, only the self -consumption premium encourages households to install them on their roof.

What is the yield of a solar panel ?

The more a solar panel is able to provide you with a large amount of energy from a given sunshine, the more profitable it will be . The question of the yield of your solar panels must therefore be at the heart of your choices in terms of technology or installation location.

How to define the yield of a solar panel ?

In the field of photovoltaic solar, the yield simply designates the ratio between the amount of energy produced and the amount of energy received . In other words, it is a question of determining the electrical power that the panel is able to produce, as a function of the power of the solar radiation reaching photovoltaic cells.

A 100 %yield, which would make it possible to convert all the solar energy received in electricity, constitutes a technical and theoretical impossibility. There are, in fact, necessarily losing energy during the transformation process. In practice, the real yield of a solar panel is generally located between 7 and 24 % (source: selectra).

This means, for example, that a panel displaying a yield of 15 % will be able to transform 15 % of the light into electricity received.

The yield of the solar panel should not be confused with its production capacity . The latter, which stems in particular from the number of panels on the house, designates the maximum electrical power that the device is able to provide, and is expressed in Watts-Cart (WC). The two concepts are therefore different, but linked. What you must remember :

  • A panel will be able to reach its maximum production capacity all the more easily as its yield is high ;
  • A very high theoretical yield will be Useless and “wasted” If production capacity does not follow.

Ask for a free study for your photovoltaic project

How to calculate the yield of a solar panel in 2023 ?

The formula for calculating the yield of a solar panel is established as follows:

Rate of yield = Power in WC / (area in m² x 1000)

A photovoltaic panel with a useful surface of 1.5 m² and whose maximum power is 275 toilets has a rate of return of:

275 / (1.5 x 1000) = 0.1833 = 18.33 %

A high rate of yield is always a desirable objective in itself to optimize your solar electricity production, but is particularly useful if you have a small roof surface . You make sure to obtain the maximum energy for each square meter of panel.

For more details, use a simulation tool or request a free study from Helio.

What type of photovoltaic solar panel for optimal efficiency ?

Hallio solar panels

There are different types of solar panels on the market. Depending on the technology retained, the silicon of the photovoltaic cells will be able to retain and transform a more or less large proportion of the solar energy received. The selection of the right model is therefore essential and must be made, preferably, in consultation with a professional installer .

  • THE Monocrystalline solar panels currently represent the most efficient offer. Their yield is generally located Between 14 and 19 % (Selectra). The higher cost of manufacturing a monocrystalline silicon lean, however € 8,000 For a power installation of 3,000 toilets (3 kwc).
  • THE Polycristalline solar panels are a little less complex and display an average efficiency of less good quality, included Between 11 and 15 % According to the case. In return, the owner can hope for an economy on the cost of purchase and installation. The latter is around € 6,500 For an equivalent production capacity.
  • THE Amorphous solar panels constitute the solution offering the less good yield (between 5 and 7 %). This generally excludes them from the domestic solar market. However, they have some advantages, including that of being more easily transportable and to work better in the event of low sunshine. Most of the time, these solar collectors are rather used for a nomadic use (outdoor hikes and excursions) or as a extra energy on a boat, for example.

The Hallio figure: 7 %

It is the additional energy efficiency that you can hope by carrying out a careful and regular maintenance of your photovoltaic installation (according to Selectra). Although the panels are not very demanding in this area, it is recommended at least to clean them at the raclette at least once or twice a year. Also take the opportunity to dust the inverter air inlets and check the different light witnesses.

Take advantage of the premiums for the installation of photovoltaic panels

Solar panels: how to optimize electricity yield and production ?

Beyond the technology used and the design quality specific to each solar panel, its environment and its installation conditions will also have an impact on its rate of return.

1- The sunshine rate

The sunshine rate in France is sufficient to make a photovoltaic installation profitable in any region . However, it goes without saying that the intensity and quality of solar radiation have an influence on the performance of the device, both in terms of performance and pure energy production. We can estimate:

  • A yield of 800 to 1,000 kWh per kwc for the northern half of the country, Ile-de-France included;
  • A yield of 1,000 to 1,100 kWh per kwc for the Brittany, THE Pays de la Loire or the Savoy ;
  • A yield of 1,100 to 1,200 kWh per kwc for theAquitaine and most of theOccitania ;
  • A yield of 1,200 to 1,400 kWh per kwc for the Côte d’Azur and the Corsica.

This estimate is carried out on the basis of optimal conditions in terms of inclination of the panels (30 °) and orientation (facing south).

2- The orientation of the panels

The orientation of solar panels is an important factor in determining their overall performance. It is best to adopt a south -facing angle to capture sunlight as much directly and as long as possible during the day. However, other orientations are quite possible depending on your constraints and the configuration of your home.

Still according to Otovo, a solar installation developing an annual production of 3,900 kWh in south orientation, with an optimal inclination of 30 °, would produce:

  • 3,744 kWh in the case of an orientation South East ;
  • 3,744 kWh in the case of an orientation South West ;
  • 3,510 kWh in the case of an orientation full -east ;
  • 3,510 kWh in the case of an orientation West west ;

In practice, a solar device facing south-east profitable in approximately 11 years (selectra). Another orientation increases the damping time to 14 years: the return on investment is therefore less rapid, but remains interesting.

On the other hand, forget the northern orientation: it is not profitable.

3- The inclination of solar panels

The solar energy received is optimized when the orientation of the panel makes it perpendicular to the radiation . However, the sun is not always at the same height in the sky; Furthermore, it depends on the latitude you live. In France, the optimal inclination is located between 30 and 35 degrees.

A bad tilt of the roof will however have a fairly limited impact on the performance of your installation. The decrease in production is limited to 10 % for a panel tilted to 10 degrees or, conversely, for a panel tilted at 60 degrees.

4- The outside temperature

Some high -efficiency and recent design panels are more resistant to high temperatures. They can limit the loss of yield to only 0.25 % per additional degree, half as much as a conventional panel.

Contrary to what one might think, photovoltaic modules do not particularly appreciate excessive heat. Beyond an outside temperature of 25 ° C, the yield of the panels even begins to fall, at the rate of 0.5 % per additional degree.

A scorching temperature of 35 ° C, for example, therefore results in a decrease of 5 %. If the rate of the theoretical yield of the panel is 19 %, the actual performance then increases to 95 %by 19 %, or 18.05 %.

An interesting technique to limit overheating is the sorreposition of the panels, so that they are not in direct contact with the roof and that the air circulates better.

Local RGE craftsmen set up your new solar panels

How is the production capacity of a solar panel determined ?

As indicated previously, the power of a solar panel is expressed in watts-key, or WC. It should be kept in mind that the figure announced by the manufacturers is obtained after a test carried out in standardized and optimized conditions, that is:

The installation of your solar panels can be subject to reduced VAT at the rate of 10 %. To benefit from it, you must use a RGE Qual’PV certified installer. The accommodation must also be completed for more than two years. Finally, the nominal power of your panels should not exceed 3 kWc (power-head). This also makes you eligible for income tax exemption for electricity sale.

  • An outside temperature of 25 ° C ;
  • An orientation directly south ;
  • An inclination of 30 degrees ;
  • A solar radiation of 1,000 watts per square meter, shading.

The power in WC then determines the production of electric current proper, which is expressed in kilowatt-hour (kWh) per year. The number of kilowatt hours produced per kilowatt-crew is variable and depends in particular on the sunshine in your region (see above).

Current solar panels display a power generally between 250 and 325 WC . Some particularly efficient models can go up to 400 toilets.


To find out all about solar panels, download our white paper !

Profitability of solar panels: what are the fixed costs ?

The cost linked to the purchase and installation of solar panels is, by far, the largest part of the investment to be made (remember to benefit from financial aid in photovoltaics). Count a little more than 10,000 euros in general.

You can then take advantage of your solar electricity for many years with a minimum of costs. Certain fixed costs are however to be expected, and in particular:

  • The replacement of the inverter must be considered at least once every ten years, so as to guarantee the proper functioning of the installation. The new equipment will be billed to you between 1,000 and 2,000 € each time (Engie). By choosing a guaranteed inverter 25 years as with Helio, you take advantage of a free change during this period. What to accelerate the profitability of the project !
  • THE Connection of panels to the public electricity network is subject to specific invoicing, for the price for use of the public electricity network (Turpe). These costs amount to around € 65 per year, still according to Engie.
  • If the installation develops a power greater than 3 kWc, the owner is indebted to income tax On the resale of solar electricity to EDF (total resale or surplus in the event of self-consumption).

Taking into account the price of the panels, annual expenses and especially the savings of electricity generated, your installation is profitable in ten years. Sometimes 8, sometimes 13. Make a precise simulation with Hellio !

Yield of solar panels: what hazards to be expected ?

Solar panels are a safe investment if you are addressing a confirmed and approved installer . A panel keeps an average of 80 % of its initial performance after 25 years of use (Picbleu), and also displays a life of 40 years . The different risks weighing on the sustainability of the yield are limited:

  • The panels are Climatic hazards resistant and especially in hail. Photovoltaic cells are protected by two armored glass sheets and can withstand projectiles launched at 140 km/h.
  • They cannot cause a fire, But can of course be damaged by a fire starting from another source.
  • Any damage suffered within 10 years of the installation can be covered under the decennial warranty, If it compromises the solidity of the work or makes it unfit to offer a good return.

By choosing to install panels with a good yield, you will benefit from an electrical production that is both abundant and renewable. However, pay attention to solar panel scams (false free offers or 1 euro). To do this, contact Helio and take advantage of the services of its network of certified installers, in order to choose the best equipment and ensure a installation that will make you benefit from optimal performance.

The three key points to remember:

  1. The yield of a solar panel is the relationship between the electricity produced and the solar energy received.
  2. It can vary depending on many parameters such as orientation, room temperature or level of maintenance.
  3. The damping of a high performance solar panel is significantly faster.

A project to install solar panels ? Helio accompanies you