How many kW of photovoltaic are needed for a 100 sqm house?

Install a photovoltaic system It is one of the smartest choices for those who want to save on their electricity bill and invest in Green energy. If we have a large, well-exposed roof, the main question is: How many kW of photovoltaic is it really worth installing?

The answer is not unambiguous, but it depends on several factors: the consumption of the family, the size of the roof, the habits of energy use and the characteristics of the solar panels. Let's see how to calculate in a simple and realistic way the necessary power and the economic advantages of this choice.

Why is it important to calculate the right power

Un photovoltaic system it's a significant investment. Sizing it correctly means:

• avoid a system oversized, too expensive and difficult to amortize;
• Prevent an implant undersized, which is unable to cover household consumption;
• get a clear picture on costs, inducements and Return times.

Given these factors, let's now do the calculation in practice.

How to calculate the power needed per 100 square meters

To understand how many kW photovoltaic we need, we need a measurement for our home: 100 square meters they can be an optimal starting point to make the calculation easier and more understandable, corresponding to the size of a typical house of an average family.

But is it really that important to do this calculation? In reality, yes, because it is important to make the most of the space we have available. In fact, if we install an excessive power system, we risk incurring purchase and maintenance costs that are too high. If, on the other hand, “we are low”, the risk is that production will not be able to meet the energy needs of our home: so we will find ourselves having made a substantially useless expense.

To correctly calculate how many kW of photovoltaic energy we need, however, we must take into account some factors, which have an important influence on this value.

The factors that influence the sizing of the photovoltaic system

The factors that make it possible to determine how many kW of photovoltaic we need are different. There are some that we can define as' key 'and that we absolutely cannot ignore in our calculation:

1. Electricity consumption: it's not difficult to calculate what our average daily electricity consumption is, we simply need a recent bill and a calculator. We divide the total kWh consumed by the number of days we have consumed them and that's it. Normally, a family consisting of 3 or 4 people, with a house of 100 square meters, has an average daily consumption that ranges between 10 and 15 kWh;
2. Features of the house: if our home is equipped with classic appliances (washing machine, dishwasher, electric oven) a power equal to 3 kW may be sufficient. If, on the other hand, the house is highly “electric”, with energy-intensive devices, such as electric boilers, induction plates and heat pump heating systems, the necessary power is at least 4.5 kW; in addition, modern and isolated homes reduce the need for electrical power;
3. Family habits: such as the frequency and use of electrical and electronic appliances and devices.

How many panels are needed and how much energy do they produce

After calculating how much energy we need, we must understand how many panels we need to meet the needs of our home. Even in this case, there is no single answer, because we must consider different factors: first of all, how much energy they can produce, given that we can derive the number necessary for our plant.

Let's arm ourselves with a calculator again (or use one of the many simulators that are available online) and let's start from the assumption that our home needs a 3 kW power system. Considering that the average power of the most popular panels on the market ranges from 300 to 400 watts, let's imagine choosing 350-watt panels.

At this point we only need to apply a mathematical formula, so: 350 watts (power of the single panel) * 9 = 3150 watts = 3.15 kWp.

The kWp abbreviation indicates the “peak kilowatt”, that is, the power of all the modules under ideal radiation and temperature conditions: and 3.15 kWp are more than enough to cover the needs of a consumption of 3 kW.

Obviously, even in this case, several factors come into play, including:

1. the roof exposure conditions: which can make us focus on different types of panels;
2. the size of the roof: which may determine the need for a smaller number of panels, which must therefore be more powerful.

Final costs and conclusions

At this point, having calculated the number and type of panels we need, we can also know the cost of our photovoltaic system. Always wanting to make an average between the different products, we can start from a cost of 6000 euros, destined to rise if we choose particularly high-performance photovoltaic panels.

Once the cost has been calculated, we can also see what incentives we are entitled to for the installation of a photovoltaic system: for 2025 there is a deduction of 50% of the amount spent (for the first home), up to 96,000 euros. Deduction that provides for an annual personal income tax refund in 10 installments of the same amount.

And how soon could we return the expenses incurred? Also in this case, we can use a fairly simple formula: the cost of the plant (net of deductions), which must be divided by the savings in the bill (and any income derived from the sale of unconsumed energy). The result allows us to understand in how many years we could recover expenses, even if the calculation may be more accurate taking into account other factors, such as the degradation of the panels and the geographical position of our home.

Too many calculations to do and too many variations to consider to understand how many kW photovoltaic should be installed for our home? Or don't we have a roof available? The simple solution available to everyone is there and it is that of shared solar systems built by GridShare: a step forward for the democratization of access to photovoltaic, with the aim of reaching an increasingly large and widespread audience of users.