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Relationship between the number of solar panels, the inverter and the batteries in a solar installation

It is important to know exactly the relationship between the number of solar panels, the battery and the inverter when we think about installing a solar system.

For the correct dimensioning of a solar kit, it is necessary to calculate the number of solar panels, power and voltage, the type of inverter that must meet the expectations of the installation and the batteries, which must cover the storage needs to achieve maximum autonomy. .

All this while achieving amortization as quickly as possible, the expected energy savings and, of course, the compatibility between the elements. The following explains how to select each of the elements to make the solar kit that best suits specific needs.

Relationship between the number of solar panels, the inverter and the batteries in a solar installation

To begin with, the charging current produced by the panels cannot exceed 10% of the battery capacity expressed in C10 . The battery can be expressed in C10, C20 and C100.

 

For example, for a 550Ah battery, the maximum allowable charging current is 55A. The personalized photovoltaic study will always adjust to the daily consumption of the most unfavorable months, that is, with less solar radiation. For this calculation we will base ourselves on an average day in the winter months. It is very important when sizing, the use of the photovoltaic installation if it will be for weekends, summer house, permanent home. For this calculation we will base ourselves on an average day in the autumn months.

Peak Solar Hour (PSH) is a unit that measures solar irradiance and is defined as the energy per unit area that would be received with a hypothetical constant solar irradiance of 1000 W/m2. In each place there will be a series of HPS, therefore they will significantly influence the sizing calculation. Other aspects that are also important for the calculation will be losses such as:

– System losses

– Dirt losses

– Heating losses

We take all these aspects into account when adjusting a personalized solar kit so that it can self-supply its consumption. In such a way that on the most unfavorable days we can supply the necessary energy. In our kits that can be seen on the website, you can see the average energy produced by the panels, which is expressed in Wh/day, both in the summer and winter months.

Regarding the capacity of the batteries, the solar kit will depend on the capacity of the batteries to determine the autonomy of that installation. It is recommended that the battery is not discharged more than 50% depth of discharge. So we will multiply that battery capacity by 2 to avoid the depth of discharge and then multiply by the number of days we need to determine autonomy.

To adjust the days of autonomy, it will depend on the HPS of the geographical location of our installation. In areas where the HPS are lower, it is advisable to put batteries with more days of autonomy than in areas where the HPS are higher and therefore there is more solar radiation at the end of the day.

Examples at 12V:

A consumption of 3000 Wh/day for a range of 2 days

3000Wh/day x 2 days = 6000Wh/day

This energy produced will be divided by the terminal voltage to determine the battery capacity, in this case the battery is 12V.

6000Wh/day / 12V = 500 Ah

This battery capacity will be formed with different configurations:

– A 12V 500Ah battery

– Two 6V batteries in series

– Six 2V batteries in series

Example at 24V:

A consumption of 3000 Wh/day for a range of 2 days.

3000Wh/day x 2 days = 6000Wh/day

This energy produced will be divided by the terminal voltage to determine the battery capacity, in this case the battery is 24V.

6000Wh/day / 24V = 250 Ah

This battery capacity will be formed with different configurations:

– Two 12V batteries in series

– Four 6V batteries in series

– Twelve 2V batteries in series

Example at 48V:

A consumption of 3000 Wh/day for a range of 2 days.

3000Wh/day x 2 days = 6000Wh/day

This energy produced will be divided by the terminal voltage to determine the battery capacity, in this case the battery is 48V.

6000Wh/day / 48V = 125Ah

This battery capacity will be formed with different configurations:

– Four 12V batteries in series

– Eight 6V batteries in series

– Twenty four 2V batteries

Regarding the voltage and power of the inverter: for 12V installations, an inverter power of less than 1000W is advisable, for 24V installations, an inverter power of between 1000W and 3000W is advisable and for 48V installations, an inverter power of less than 1000W is advisable. greater than 3000W.

If you are thinking of buying a solar kit, contact us and our technical team will advise you without obligation on the necessary elements to make the kit that meets your needs.

Read more about: Connection of solar panels: types and points to consider