How many kWh does a solar panel produce?

So let’s see in detail how many kWh a solar panel produces, what that power depends on and everything we must take into account .

As we will see, the panels have different numbers in this regard, but we have to understand what they really mean.

How many kWh does a typical solar panel produce?

The answer to how many kWh a solar panel produces is that it depends, because the panels have different powers , just as cars or computers have different capacities.

In addition, over time, the power of solar panels has also been rising, while their prices have been falling.

The generation power of a solar panel is measured in watts (W) and you will find it specified in the panel you are looking at for your installation.

A typical solar panel can provide between 250W and 300W of power . However, it is increasingly common to see domestic panels with higher power, such as 500W, and also some with lower capacity (such as 150W).

This can help us easily know the kWh that a solar panel produces each day. 

If we take a typical panel of about 300W, this means that for every hour of sunshine it will generate that power .

Thus, if we calculate a sunny spring day, for example, in a warm area, the calculation would be:

300W x 5 hours of sunshine per day = 1500W or what is the same, 1.5 kWh per day.

If we assume (greatly simplifying) that these 5 hours are the average annual sunshine (compensating the fewer hours of winter with the greater hours of summer), it would give us:

1.5 kWh per day x 365 days per year = 547 kWh per year per typical 300W solar panel.

In this way, looking at the consumption of kWh that we need (an average Spanish home has a consumption of about 8,000 kWh per year), we can size the installation according to our needs and calculate how many panels it must have.

However, these calculations reveal something very important to keep in mind when we want to answer how many kWh a solar panel produces.

The importance of the hours of sunshine and its impact on the kWh produced by a solar panel

In our simple example we have calculated 5 hours of sunshine in a warm area during a spring-summer season. Isn’t that not enough for places like Valencia, Seville or Malaga, for example?

Actually, we have to keep in mind that when we look at the wattage of the solar panel and we see 300W or 500W, the manufacturer is talking about the power that the solar panel generates in optimal conditions .

However, these optimal conditions do not exist equally in all areas or all the time.

In this way, there can be up to 8, 10 or 12 hours of sunshine in both Bilbao and Valencia in summer, but they are very different hours of sunshine .

The incidence is more powerful in warmer areas , so it is likely that in them the solar panel does approach that optimum power of 300W more often during the year. But in other cases, no.

The advantage of new materials and innovations in solar panels mean that, even on a cloudy day, they can extract energy. However, it will not be all that they can.

Therefore, when it comes to knowing how much power a solar panel actually generates, we should take into account:

1. The power of the panel on paper (the watts that we see in the catalog or on the label).
2. The hours of sunshine that it will receive in the place where it is installed.
3. The incidence of the sun in that place and, therefore, the radiation it emits.

This is so important that even the European Union has designed a tool that calculates the radiation and energy that can be generated with photovoltaic panels, depending on where you are located.

Of course, to use it correctly we will have to have some technical knowledge about these issues.

As we can see, a solar panel has a nominal generation power of which it is capable in optimal conditions and we must be guided by it.

However, it is very possible that many days, depending on the area, it will not reach it. That is why we must always take into account the 3 previous points. Without them, we will not be able to calculate well how many kWh that panel can generate.

What power in kWh should we choose in a solar panel?

Again the answer is that it depends. In this case of:

• Our budget .
• Our energy consumption and how much we want to cover with solar self-consumption.
• The installation space .

Obviously, higher wattage panels, while they can be larger, can also take up less space in total. However, they will also be more expensive, although they may be cheaper on the whole than a greater number of lower power panels.

How many we will need and how much the solar installation will cost us per kWh we already told you about in its day.