Is it worth investing in a photovoltaic battery? Cost-benefit analysis

Added: Tuesday, 1/7/2025


Energy storage significantly increases the efficiency and functionality of a photovoltaic installation. What are the arguments for implementing this solution? How to choose the right batteries? We explain this in a new guide.

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Do photovoltaics work better with batteries?

The combination of photovoltaics with an energy storage allows for the storage of surplus energy produced during the day, when the solar panels generate more energy than the users demand. In systems without batteries, this energy is sent to the grid, which is not always cost-effective. Thanks to the storage, the investor can store this energy for later, when demand increases.

Photovoltaic installations with batteries also provide independence from the power grid. In the event of a power outage or interruption, the energy stored in the batteries can power a household or company, ensuring continuity of power supply. This is especially important in regions where power outages are frequent or long-lasting.

How to choose a battery for the PV installation parameters?

When choosing an energy storage for photovoltaics, you should consider several factors. The specifics of the installation and the energy demand of your household are of primary importance. You can choose individual battery parameters in this respect:

Construction

Qoltec AGM battery 6V 1.3Ah max. 19.5A 53041 In photovoltaic installations, lithium-ion, lead-acid and sodium-ion batteries are most commonly used. The former are characterized by high efficiency, long service life (up to 10-15 years) and the possibility of deep discharge (up to 90 percent). They are lightweight and take up less space than lead-acid batteries. They are also more expensive, but their longevity and higher energy efficiency make them a cost-effective solution.

  1. Lead-acid batteries are cheaper, but they may be a less advantageous choice. They have a shorter service life, usually 3 to 5 years. They also fare worse in terms of maximum depth of discharge (usually to about 50 percent of capacity). They also require more frequent maintenance – they are susceptible to corrosion and have a tendency to leak electrolyte.
  2. Sodium-ion batteries are even less popular, but they can be an interesting alternative to lithium-ion and lead-acid. These types of batteries are cheaper and can have a longer life than lead-acid batteries, but you won't find many models on the market right now.

Capacity

This parameter is measured in kilowatt-hours (kWh) and determines how much energy the battery can store. When choosing it, you should consider:

  • household energy consumption : estimate the average daily energy consumption of your household or business and select a battery that will be able to meet these needs (especially at night or on cloudy days when the PV installation will not be producing energy) for a given period;
  • PV system power : the battery capacity must be adapted to the installed power of the photovoltaic system. A conversion factor is usually used suggesting that the battery capacity should correspond to approximately twice the daily energy production. So if the system generates 10 kWh of energy per day, a battery with a capacity of 10-20 kWh will be recommended.

Energy efficiency

Battery AKU_7 Gazex It determines the ratio of energy that the battery is able to give off to the energy that it has taken in. The efficiency of lithium-ion batteries is usually higher than that of lead-acid batteries, usually in the range of 90 to 95 percent.

Durability

Each battery has a certain number of charge and discharge cycles. Lithium-ion batteries can withstand 3,000 to 5,000 full charge cycles. In the case of lead-acid batteries, the number of charge cycles is much smaller (around 500-1,000), which may mean that the battery needs to be replaced after just a few years of use. Lithium-ion batteries are also characterized by greater resistance to temperature changes and better properties in extreme conditions.

In what types of installations is photovoltaics with a battery best suited?

Photovoltaics with energy storage will work well both in households and commercial facilities. In home installations, it allows for greater energy independence and better use of the energy generated by the panels. In the event of a power grid failure, a photovoltaic installation with a battery can act as an emergency power supply system. The energy can also be used to power a heat pump.

Energy storage is also very cost-effective in summer homes – especially those located in remote or mountainous areas where access to the power grid is difficult. Batteries allow for the storage of energy, thanks to which summer homes can function even in the event of a long lack of sunlight.

Volt AGM 12V 200 Ah 6AKUXAG200 battery In small and medium-sized enterprises, a photovoltaic system with a battery can bring significant benefits in the form of energy cost savings and improved energy efficiency. Companies that operate around the clock or have irregular working hours can optimize their power consumption and use it at night as well.

In farms that also draw energy at night or during periods when solar energy production is limited, an energy storage will allow full use of energy from the panels. This solution ensures the stability of operations, making the farm independent of the energy supplier and enabling work even in the event of a failure, for example.

Thanks to batteries, it is possible to store surplus energy produced during the day, which allows it to be used during periods of lower sunlight, as well as in emergency situations when access to the power grid is difficult. This is an excellent solution for various investors - both individual and business.

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