Pv panel size: A complete guide

The Pv panel size is an issue to take into account when sizing our photovoltaic installation.

The ironic phrase “the big donkey, walk or not walk” is often used as a criticism of people who choose something simply because of its larger size. It is also used to make certain products more expensive: “if it is bigger, it necessarily has to be more expensive” ; ignoring the rest of benefits. It seems as if everything big is better than everything small. But like all popular sayings, they are not applicable to all circumstances.

Pv panel size

At Cambio Energético we know this well, we have been installing solar panels for many years and learning from the different pitfalls that we have encountered. An experience that we want to share with you, to make your transition to solar energy as easy as possible.

And one of these learnings is that we should not only look at one feature , be it price, capacity or size, to select a product. This is especially important in photovoltaic installations, with an estimated useful life that can exceed 25 years.

In this article we will see what size of solar panels may interest you , depending on the requirements of both your needs and the place where you are going to install your solar panels.

How much space do you have for your solar panels?

To be able to decide on the type and size of solar panels you need, it is important to first know how much surface area you have for your photovoltaic installation.

And here, especially when we talk about roof installations, it is essential to take into account the obstacles that you can find on your roof.

These obstacles can be of two types:

• Physical: from chimneys, ventilation elements, to an elevator or window in the attic, among others. These are elements that physically prevent the placement of panels.
• Shadows: one of the main things to avoid is shadows that can affect your installation; since these can limit the power of the affected solar panel and the rest of the panels in the same chain connected in series, if you do not have power optimizers or microinverters.

However, there are installations in which there is no other choice but to install solar panels in places where occasionally and during certain times of the day they may have shadows with the aim of achieving greater total photovoltaic production. In those cases, there are ways to reduce their impact using, for example, solar optimizers, as we explain in this blog post on how shades affect solar panels .

What size of solar panels may interest you for your installation?

Solar panels of larger physical size generate, in general terms, more photovoltaic energy than others of smaller size. Or put another way, plates with higher peak power (Wp) tend to be larger in size than those with lower power.

This is something that should not surprise anyone, since the larger the panel frame, the more photovoltaic cells it can include, or they will be larger. And, since the cells are responsible for capturing sunlight, the greater the number or the larger they are, the more energy your panel will be capable of producing.

In this sense, if you want to install solar panels in your company , and it has large roof surfaces (for example, industrial buildings), it may be convenient to install 490 Wp or 530 Wp solar panels. This considering that we are talking about a pitched roof in which the recommendation may be to carry out the installation with coplanar structures .

Now, what happens if you want to install photovoltaic self-consumption in your home ? In this case, you may not have large surfaces to locate the solar panels.

This is when you should pay special attention to the size of the modules. Why? Because although large solar panels produce more than smaller ones, when you have limited space, you may find it more difficult to make good use of the space and, therefore, to install a greater number of plates, making your roof not reach produce what it really could by not being able to take full advantage of its surface.

That is why large solar panels in residential self-consumption may not make much sense . For this type of installation, a suitable size would be that of 450 Wp solar panels , around 14 cm smaller than those of 490 Wp. In this way, you will be able to take better advantage of the space, installing a greater number of solar panels.

But let’s see it with an example:

Comparison using different sizes of solar panels on a residential roof

Imagine that you want to install solar panels in your house and you don’t know whether to opt for 490 Wp or 450 Wp modules.

With our installation design program we have prepared a simulation of the number of solar panels of both powers that we could place on the same surface.

On the one hand, we have selected a 490 Wp monocrystalline solar panel , whose dimensions are 225 cm high by 104.8 cm wide and 3.5 cm thick.

As you can see in the previous image, in the right half of the sloping roof we can place 8 solar panels of 490 W. This would mean an installed power of 3.92 kWp .

On the other hand, we have done the test with a 450 Wp monocrystalline solar panel , whose dimensions are 210.8 cm high, 104.8 cm wide and 4 cm thick. This supposes, as we said before, a 14.20 cm difference in the height of one and the other solar panel.

Therefore, even producing more 490 Wp panels, in this case we see how it suits us for residential self-consumption to install 450 Wp solar panels . In the example, this choice would give you 1 kWp more power in your installation; reaching 2 kWp if we talk about the entire southern part of the roof.

Common problems of large solar panels in residential installations

structural weakness

Large solar panels have the problem that today they have a greater structural weakness, that is, they are more exposed to hot spots, micro-cracks or discoloration.

The solar panels are anchored to their fixing structures according to the specifications set by the different manufacturers. For example, with regard to the distances that the fastening staples must have.

In the case of smaller panels, the distances usually range between 30 and 45 cm. With larger solar panels these margins when anchoring the panels are much smaller. By having the panel more vain, the staples have to grip it better to the structure.

What does this mean? Basically what it means is that larger panels can be bent more easily, thus producing micro-tears, hot spots or discoloration.

Increased security risks during installation

Installers of solar panels on roofs must have, in Cambio Energético it is like that, continuous and sufficient training in Occupational Risk Prevention, especially with regard to work at height and with electrical equipment.

That is why it is important to make their work as easy as possible so as not to put their safety at risk at any time.

The larger size and weight of the panels makes handling and placement by installers much more complex, thus increasing the risk for installers on pitched roofs, and also increasing installation costs as it is necessary to apply lifting element (baskets or cranes) with greater capacity.

Manufacturer Trends in Solar Panel Size

The size of solar panels will continue to increase. But, as we said, the application of these larger plates will be oriented more towards industrial self-consumption than residential. In other words, the increase in the sizes of photovoltaic modules will be directed, for example, at the installation of solar farms, but not for homes, given the space limitations that we have been commenting on in this article.

What residential self-consumption can benefit from is the tendency of some manufacturers to bet on improving the quality of compact solar panels , easily adaptable to homes with small roofs.

So if you don’t have enough space on the roof for the photovoltaic installation you had in mind, you can opt for high-efficiency solar panels . These, although they tend to cost more, generate more energy per square meter. They are particularly good at converting sunlight into electricity, offering conversion rates of around 20-22% (the industry standard is closer to 18%). So you can amortize them in the medium term with the savings on the electricity bill .