How Many Photovoltaic Panels Are Needed for a House?

Are you wondering how many solar panels are needed for a house? Are you also considering solar panels as a good energy-saving solution for your home?

In this article, we will try to answer these questions. We hope to convince you to choose this type of green energy source.

Energie Verde

More and more Romanians are interested in solar panels for their homes and commercial spaces. We assure you that you are not the only person with numerous questions regarding this new energy source. However, the one mentioned above is just one of them.

But let’s see together how many solar panels are needed for a house and which are the best panels.

How many solar panels are needed for a house?

To determine the required number of solar panels for a house, we need to know the current monthly electricity consumption.

ATTENTION: We do not need the house’s surface area or the number of residents to determine this.

The simplest way to find out the current monthly energy consumption is to look at the last bill and check the total amount paid for one month. Then we divide this amount by the cost per kWh.

Panouri fotovoltaice

To make it easier, let’s use the following example: 180 RON (last month’s bill), 0.60 RON (cost per kWh). In this case, the energy consumed in one month is 300 kWh.

We divide the 300 kWh by 30 days (average monthly) and get a result of 10 kWh per day, which is the daily energy requirement.

So, we now know how much energy we consume daily. But how do we find out how many solar panels are needed for a house?

We divide the 10 kWh by a coefficient of 3.3 (explained below) and determine the INSTALLED POWER, which in our case is 3 kW.

ATTENTION: Energy is measured in kWh, and installed power is measured in kW.

Considering that most solar panels are 250W, we find that we need a total of 12 solar panels (1 kW = 1000W). If you are considering panels that produce less energy, adjust the calculation accordingly.


To determine an approximate price of a photovoltaic kit, in addition to the panels, take into account the other necessary elements:

  • Inverter
  • Cabels
  • Battery
  • Grip structure
  • Wiring

Coefficient of 3.3: Annual Daily Average

The installed power produces energy based on the intensity of sunlight: less in the morning, more at noon. This also applies to summer vs. winter.

In our example, even though the 12 panels have an installed power of 3 kW, they will not produce 3 kWh (energy) every hour and every day. Considering that in summer, these 12 panels (installed power) can produce even 5-6 times more energy, the ANNUAL DAILY AVERAGE has a coefficient of 3.3.