# solar panel sizes and wattage

In this article we will discuss the solar panel sizes and wattgae, which are important factors in choosing the best solar panels. Solar panels are devices created to take advantage of solar energy and transform it into electricity.

If we are going to install a series of solar panels on the roof of our property, we must take into account how many are going to fit, if the roof is going to support the weight of the panels, etc. That is why I have decided to do some research and make an article that will prove useful.

## Solar panel sizes and wattage

What are the dimensions of the solar panels? The length and width of the solar panels can vary from one brand to another. In general, the most used dimensions for solar panels are 60 cells for residential use with 164cm x 99cm and 72 cells for industrial use with 196cm x 99cm.

These are the most used measures although there are others that must also be taken into account. Knowing these technical data can be decisive when choosing a type of plates. Weight, dimensions, and capabilities may vary from model to model. Later I will explain everything you need to know.

## How to Calculate the Dimensions of Solar Panels According to their Voltage and Number of Cells

Solar panels are made of silicon blocks which are cut in their manufacturing process. With them, a series of cubes are created that are called cells.

These cells are the squares that we see in the solar panels once they are finished. Each of them can produce 0.5 volts and once connected to each other and placed in a solar panel they add up what that panel is capable of producing.

By connecting a certain number of cells we increase the voltage that a solar panel is capable of producing. Therefore, the more cells that are connected in series, the higher the voltage it produces and therefore the larger the size of the plate in question.

Now that we know how to obtain the dimensions of a solar panel, we must know what it is for us to know this information and if it will help us in our decision-making about our solar installation.

## What is the use of knowing the dimension of a solar panel?

Knowing the dimensions of a solar panel will provide us with a series of very useful data when determining the most important aspects of our solar installation, so pay attention:

As we have already seen, knowing the size and the number of cells that a solar panel has will help us to know its voltage .

Knowing the power that we are going to generate, we will need to know the type of battery that will house the energy produced in case we want an installation 100% disconnected from the electrical network.

For example: If we have a panel with 36 cells, we will obtain a result of 36 cells x 0.5 Vw each cell = 18 Volts.

Now, an 18 volt solar panel is perfect for a 12Vw battery since we will always need a higher power to charge a lower voltage battery.

If we have a 24Vw battery, double that of the previous one, we will need a solar panel that produces about 36Vw, which will translate into a 72-cell solar panel.

But what if we have a 48Vw battery? Normally manufacturers do not usually produce solar panels larger than 72 cells, therefore the solution that is reached is to connect the solar panels to each other. These can be either 2 of 72 cells or 4 of 36.

On the other hand, if what we want is a solar installation that is not necessarily disconnected from the electricity grid and therefore does not depend on the use of batteries, we will use electricity inverters, which make it possible to connect the energy produced by the panels solar panels to the property, so the battery restrictions disappear.

This allows solar panel manufacturers to play more with the number of cells in each panel and therefore with the dimensions. That is the reason why the size of each solar panel can vary from one manufacturer to another despite there being a general standard (60 cells for residential use and 72 for industrial use).

## What is the weight of the solar panels?

Before carrying out a solar installation on the roof of our property, we must take into account whether it will support the weight of the installation.

The weight of the solar panels varies according to the number of cells it has and therefore its size.

Depending on the charging power produced by each solar panel, you can see the weight of each of them in the following table:

As you can see, these measurements can vary a lot and a smaller size can also be used to charge batteries of the same voltage. What does change for each size are the Watts that are capable of injecting into the electrical network, so we must take this into account when choosing our solar panels.

## How many solar panels can I put on my roof?

To know how many solar panels will fit on my roof, we must know its dimensions and characteristics.

A sloping roof to a greater or lesser degree, a flat roof, a gabled or 4-pitch roof, etc. will not be the same.

Knowing the total surface of our roof, we can divide it by the dimensions of the solar panels that we are going to choose. In this way we will be able to know what are the dimensions of the solar panels that will allow us to put the maximum number on our roof.

Similarly, if we plan to put solar thermal panels we will have to take into account the space reserved for them and therefore we will put a smaller number of photovoltaic ones.

## Dimensions and Weight of Solar Thermal Panels

If, on the other hand, what you want is to make a solar hot water installation, the dimensions and weights are totally different from photovoltaic panels.

One variable to take into account will be that the net weight of the panels must be added to the water that will run through the interior pipes. Therefore, its weight can be multiplied x2 once installed.

The dimensions are as follows:

Once again these dimensions may vary from one manufacturer to another but we can take these measurements as the general rule.

## Cómo calcular la potencia y el tamaño de un panel solar

¿Deseas tener electricidad en una caseta aislada o para irte de camping? En estos casos la instalación de un panel solar es evidente, sólo hay que calcular la potencia necesaria y el tamaño del panel solar. He aquí las fórmulas de cálculo que debes aplicar.

## Características importantes

• Energía eléctrica producida y consumida
• Potencia
• Incidencia del sol
• Rendimiento
• Pérdida de rendimiento

La cantidad de energía eléctrica se expresa en vatios hora o Wh. Se trata simplemente de multiplicar la potencia en vatios, por el tiempo durante el cual se consume o se carga. Por ejemplo, un radiador de 1000 vatios encendido durante una hora habrá consumido 1000 Wh o 1 kWh. El kWh es la unidad de medida estándar que puede encontrarse en las facturas de tu proveedor de energía.

Para estimar la necesidad de energía de cada uno de tus aparatos, basta con multiplicar la potencia nominal en vatios por el tiempo de uso en horas. Obtendrás en Wh la cantidad de energía mínima a producir para alimentar tus aparatos.

Cabe señalar que la potencia producida por un panel solar es mayor a mediodía que al comienzo de la mañana o a última hora de la tarde, necesitarás seguramente recurrir a una batería para almacenar la electricidad y a un conversor para alimentar tus aparatos.

## Qué factores influyen en la producción de electricidad de un panel fotovoltaico

La producción de energía de un panel fotovoltaico depende tanto de la calidad del equipo, como de su entorno y del circuito que alimente.

### La potencia del panel solar

Expresada en kWp o kilovatio-pico, se trata de la potencia eléctrica producida en condiciones ideales. Según la tecnología, un metro cuadrado de panel solar puede producir de 60 a 150 Wp. Una vez conocida la potencia pico podrás calcular la superficie total de paneles solares que necesitarás.

### La radiación solar de la zona

Se producen menos de kilovatios hora (kWh) por kw pico (kWp) en Galicia que en Málaga. Esta magnitud, el sol, es interesante porque permite evaluar la producción anual teniendo en cuenta el lugar donde se instala el panel a partir de la potencia pico de los paneles.

### Rendimiento de la instalación

Si el panel no está orientado al sur y con un ángulo de 30-35° con respecto a la horizontal, produce menos electricidad de la que es capaz, ya que la superficie soleada es menor. Tener en cuenta este rendimiento permite mejorar la instalación.

## Cómo calcular la energía producida

La energía total producida E_p representa el número de kilovatios hora (kWh) producido por el panel en un año. Se calcula utilizando la siguiente fórmula:

Ep=r*Ens*PC

Pero lo que te interesa es calcular la potencia pico del panel que deseas comprar para cubrir tus necesidades de electricidad o vender una cierta cantidad de energía a un proveedor de electricidad.

Al transformar la fórmula anterior, se obtiene :

P_C≥(E_p*F_CO)/E_ns

con F_CO=1/r con un coeficiente de corrección para compensar las pérdidas de rendimiento.

### Rendimiento de un panel

El rendimiento de un panel depende de sus componentes:

• 6% para silicio amorfo;
• 15% para silicio policristalino;
• 16 a 24% para silicim monocristalino.

• kWh : kilovatio hora
• kWp : kilovatio-pico
• E_p : energía total producida
• r : rendimiento
• Ens : sol
• P_c : potencia de pico
• F_co : factor correctivo

## Cómo determinar la radiación solar E_ns

Consulta el siguiente mapa. Localiza el lugar donde vayas a instalar los paneles solares, mira de qué color es la zona donde te encuentras y consulta la leyenda. En caso de duda, toma el valor de radiación solar más pequeño para mayor seguridad.

### Atlas de Radiación Solar en España. Fuente AEMET(c) Agencia Estatal de Meterología

Cómo compensar las pérdidas de rendimiento

In the following table you can find by  what factor to multiply the annual production of the panel to compensate for losses related to orientation problems .

 West Southwest On Southeast East 0° 1,075 1,075 1,075 1,075 1,075 33° 1,111 1,042 1 1,042 1,111 45° 1,190 1,087 1,042 1,087 1,190 60° 1,282 1,136 1,099 1,136 1,282 90° 1,818 1,515 1,471 1,515 1,818

Correction factor F_CO=1/r

The losses in  the conversion, the storage in the battery or the passage through the cables , suppose an order of ten percent. They depend on your installation and are difficult to assess accurately without knowing the nature of each installation. Choose a sufficient margin if you are not sure.

## Summary of the different abbreviations and their meaning

 Abbreviation Definition IN watt Wh watt hour kWh kilowatt hour kWp Peak Kilowatts P Power P_p peak power AND Energy E_p Total energy produced r Performance F_CO Correction factor E_ns solar irradiation

## conclusion

Knowing the dimensions of the solar panels will help us to better understand the characteristics and restrictions that we have to accept when putting them on our roof.

Decisions like What voltage do we need? What are our energy needs? Do we want an installation connected or disconnected from the electrical network? And if so, what batteries will we need according to the type of solar panels that we will install?

All those questions can be answered by taking into account everything you have learned in this article.

I hope it has been helpful and that you now know how to best choose the solar panels for your installation.