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How to connect solar panel to battery

In many cases it happens that we have a photovoltaic system without battery bank as backup, but we want to add one to our system, here I will explain How to connect solar panel to battery

How to connect solar panel to battery

Before explaining how to connect a solar panel to a battery, it seems correct to clarify what a solar battery is, since it is one of the elements present in many solar installations, but the one that is least often talked about.

What is a solar battery and what function does it have?

Solar batteries are special energy accumulators that can store the energy that is produced in the solar panels and that is not consumed instantly in the house. The solar battery is used to have a reserve of energy for when the plates do not work or to compensate for the difference between what is consumed and what is produced at certain times.

We also find batteries in special equipment, such as some traffic signals or isolated night cameras. Here, the battery is accumulating energy throughout the day so that the lights or cameras can work at night.

The ignorance on the part of the general public of what a solar battery is may be due to the fact that it is a more discreet element. He is usually out of sight and less talked about in the media. Solar installation is synonymous with solar panels for many. But a photovoltaic installation is much more than the panels that capture the energy, although these are the protagonists.

How to connect solar panel to battery

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In some installations, solar batteries are not present. But this is not always so. In photovoltaic installations connected to the network with the sale of surpluses , they are not usually mounted, since here the objective is to have as many panels as possible. Consume almost all the energy needed and pour the rest into the network. The night goes into the background, because the energy needs are less and, normally, the energy of the network is pulled.

But it would also be possible to mount solar batteries in these cases and consume the energy stored in the batteries at night or when we have cloudy days. Having batteries always allows us to take more advantage of solar energy and depend less on the energy of the distribution network.

The solar battery is essential in isolated homes that are not connected to the electricity grid. Without batteries we would not have light neither at night nor when the day is very cloudy. At night, solar panels cannot capture energy, and on cloudy days they capture much less than what we usually need. Well, to compensate for these deficits, batteries connected to solar panels are installed.

How to connect solar panel to battery

Thus, once it has been clarified that the option of connecting solar batteries is profitable in many circumstances. With them we can take more advantage of the capacity of our solar panels, reserving what we do not consume, or ensure a continuous supply of energy in any circumstance.

Connecting a battery to solar panels is a relatively simple task. But if you do not see yourself capable of it or you cannot calculate the number of batteries you need, it is advisable that you put yourself in the hands of professionals . There are different battery technologies and brands that are better and some that are worse. It is always good to be well informed before making the purchase decision.

How to connect solar panel to battery

Calculate the amperage

Before purchasing a battery we need to calculate the amperage of the battery to know how many panels we have to connect so that they can recharge.

The first thing we need to find out is the amp-hour rating of the battery we want to recharge. We have to take into account that batteries lose 1% of their amperage when they are not being used. So if we want to keep a 50 amp battery fully charged, we need a solar panel that can produce half an amp hour.

Since solar panels offer information on their capacity in watts, we have to know how to convert those watts to amps . To calculate the Ah of a battery, it is necessary to know the energy generated in a panel per hour Wh (power delivered in one hour) and then divide this energy by the system voltage, in isolated systems 12, 24 or 48V.

Calculate daily sunshine hours

Now we have to take into account the hours of sunshine we have in a day. Depending on the meteorological circumstances or the season of the year, the number of hours a day that we have sun varies. If we have a 100W panel running for 6 hours, we have 60 Wh (watts*hour). To get the Ah (Amps*hour), you have to divide 60 by the voltage, in small applications 12V, that is, we will have 5Ah.


To connect solar panels to the battery we need charge regulators, these can be of the PWM or MPPT type. These regulate the charging and discharging of the battery in the correct parameters. The electrical protections described are fine.

If we have to install several panels to power the battery, it is advisable to do it through a parallel circuit. This way we can use lower cost panels and also further optimize the power of the panels.

The installation of panels in parallel consists of joining the positive poles of each panel with each other with a cable and the negative poles with another different cable (positive with positive and negative with negative). The ends of these positive and negative cables go to the battery, also in parallel (+ with + and – with -).

Panels connected in parallel maintain the same electrical voltage, but the amperages of the panels add up. Thus, continuing with the example, if we place 5 panels like the ones described above in our installation, we will obtain a total amperage of 33.3 (5 x 6.66).

We have explained how to connect the solar panel to the battery . But remember that there is an electrical risk when handling the panels and batteries. If you are not trained, you should always go to professionals. And if you do, you must take all the necessary preventive measures to carry out these works.

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