How Many Solar Panels Do I Need?

The number of solar panels required for your home will be determined by how much and how you consume. The table below shows an indicative table based on consumption level (low, medium or high).

Number of solar panels according to consumption:

Number of panelsConsumption
2 – 4Up to 2,000 kWh
5 – 72,000 – 5,000 kWh
From 7More than 5,000 kWh

How many solar panels do I need based on the cost of my invoice?

Similarly, we can estimate the number of solar panels required for our photovoltaic installation based on the cost of our monthly electricity bill. It is important to remember that the price of the bill is determined by the amount of electricity consumed, but the rate that we have contracted also has a significant impact. To give you an idea of what you’ll need, based on average spending, you’ll need:

Number of Panels

Cost of My Invoice

3 – 4Up to € 50
5 – 9Between € 50 and € 100
9-10More than € 100

A photovoltaic self-consumption installation in a single-family home, for example, will require an average of three 320W solar panels for every 2,000 kWh of annual consumption. To properly select the number of plates required in our home, we must consider the characteristics of the panel as well as the characteristics of the home.

What are the factors that influence the size of solar panels?

The characteristics of each module determine the amount of energy produced by solar panels. The following are the most important considerations:

1. Capacity

The ability of the solar panels indicates how much electricity the modules can generate from solar energy. The power produced by the plates is calculated as follows:

Theoretical power * Panel count * HSP * percent

2. Performance and quality

The quality of the solar panels used in our installation will affect not only the cost of the solar self-consumption system, but also its performance and durability, and thus the payback period. As a result, it is critical to assess the type of solar panels we will use and select a manufacturer with extensive experience and a good reputation in the photovoltaic market.

Microinverters in high-end panels enable energy production to be optimized when there are shadows.

3. Orientation and proclivity

The optimal inclination of the solar panels will differ depending on the month and province. For example, in January, the ideal angle for a self-contained facility in Córdoba is 62o, and in June, it is 4o. Changing the inclination of the solar panels every month is costly; therefore, it is best to use an optimal global inclination, which in the case of Córdoba is 34o.

On the other hand, the orientation of the solar panels is critical to optimizing the installation’s performance. To maximize electricity generation, photovoltaic modules must be well oriented to the south.

What if my installation is not oriented southward?

You should not be concerned if your photovoltaic installation deviates from the south by 30 – 40o. Solar panel systems facing southeast or southwest experience losses of only 1-4 percent.

4. Solar panel type

There are numerous types of photovoltaic solar panels available on the market. We distinguish three types of materials based on their technology: monocrystalline, polycrystalline, and amorphous. The installation’s performance will be affected by the model chosen:

  1. The yield of monocrystalline panels ranges between 18 and 23 percent.
  2. Polycrystalline panels have a yield of 14 to 17 percent.
  3. Amorphous panel yield: 8 to 12 percent

Although amorphous photovoltaic panels are less expensive than crystalline ones, they require a greater number of modules and more space to generate the same amount of electricity.

5. Situation geographically

Each province in Ireland receives a different amount of solar radiation, which has a direct impact on the amount of electricity that solar modules can generate. Locations with more hours of sunlight per year will require fewer panels than less sunny locations.

Using housing factors to calculate the number of solar panels

The type of home and its characteristics must be considered when calculating the number of solar panels required for our self-consumption system. The most important aspects are as follows:

1. Roof measurements

The solar panels have a surface area of about 1.5 – 2 m2. As a result, we must ensure that we have enough surface area on our roof to complete the installation. If we have a limited amount of space, it is best to look for higher power panels that allow us to produce the same amount of electricity in the smallest amount of space.

Solar panel dimensions and performance depending on its power:

200 – 250 W1.5 m 214 – 15.5%
250 – 300 W1.7 m 215.5 – 17%
300 – 350 W1.8 m 217 – 18%
350 – 400 W2 m 218 – 20%

2. Electricity usage

The size of the installation will be determined by the amount of electrical energy consumed per month. You can check your electricity bill to find out how much electricity you use. It will show you the electricity costs for the most recent period (1 or 2 months) as well as the total for the year.

The amount of energy consumed in a given time period is expressed in kWh.

3. Working hours at home

The amount of energy that we can consume will be determined by the hourly distribution of our electricity consumption. The maximum performance of the self-consumption system is obtained when electricity is consumed while the solar panels are in use, i.e. during daylight hours.

Who should be in charge of dimensioning my solar installation?

The sizing of a self-consumption system should be performed by a qualified technician who has the necessary knowledge to evaluate the number of solar panels that the house requires based on the energy needs and the house’s characteristics. It is preferable to be aware of the factors that influence; however, an extensive study must be conducted to ensure that the project can be completed without incident.

How do I request that a solar study be conducted in my home?

1. If you are considering switching to self-consumption, the first step is to request an indicative budget. To do so, you must provide a number of details in order for us to offer you a home and consumption-specific alternative. A utility bill is the most appropriate piece of information for making the most competitive offer possible.

2. Within 24 – 48 business hours, you will receive a proposal outlining your solar installation, how much it would cost, and how much you could save. If you find it appealing, you can request that a solar study be performed in your home in order to communicate the final price and learn more about your solar installation. This is what it is:

  • The number of solar panels needed
  • Where will the photovoltaic modules be placed? (in series, parallel or mixed)
  • The installation’s orientation and angle of inclination
  • Estimated self-consumed energy production Estimated surplus generation
  • Estimated amount of grid energy consumed
  • Estimated annual savings and payback period

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