Solar home battery systems can be used both as a component for storing electricity, produced in excess by photovoltaic panels at times of lower energy demand and also as an emergency supply. In the latter case, however, the question arises as to how long there will be enough electricity in the home solar battery storage during an emergency and what this depends on. So we decided to take a closer look at this topic.
Solar home battery system as a backup battery power supply
The use of solar home battery systems for energy storage and backup battery power supply is a solution that works well for businesses, farms, and private homes alike.
What does the duration of the power supply provided by a solar home battery system depend on?
As you can see, the use of solar home battery systems also in the role of emergency power supply is an extremely cost-effective solution for both economic and convenience reasons. Deciding on them, however, you need to select them appropriately to your needs, so that the time for which power will be maintained by the solar home battery system meets them in full. And to check whether they are certainly equipped with appropriate technology that allows not only to store energy from surplus and use it at times when the photovoltaic installation does not work or works less efficiently, such as at night or in winter, but also to solar battery backup for home devices.
Power and capacity are the key parameters
How much is enough, on the other hand, depends on its two parameters of power and capacity. A device with a large capacity and low power rating is able to power a small number of the most necessary household appliances, such as a refrigerator or heating control. On the other hand, those with a small capacity but high power can successfully supply backup power to all devices in the house, but for a short time. Therefore, it is so important to choose these parameters for individual needs.
What is the capacity of a solar home battery system?
The capacity of a solar home battery system defines how much electrical energy can be stored in it. It is usually measured in kilowatt-hours (kWh) or ampere-hours (Ah), similar to car batteries. It is calculated from the voltage at which the energy storage device works and the capacity of the battery expressed in Ah. This means that energy stores with a 200 Ah battery operating at 48 V can store around 10 kWh.
What is the power of a home solar battery storage facility?
The power (rating) of a home solar battery storage facility tells you how much energy it is capable of supplying at any given time. It is expressed in kilowatts (kW).
How do I calculate the power and capacity of a home solar battery storage facility?
In order to calculate how long the home solar battery storage will last, you first have to decide which appliances you want to power and then calculate their total maximum output and their daily energy consumption in kWh. In this way, it can be seen whether a particular home solar battery storage model with lead-acid or lithium-ion batteries is capable of supplying all appliances, or only selected ones, and for how long.
Solar home battery system capacity and supply time
For example, if for a total output of 200 watts of power to the appliances, via photovoltaic installations, and their power consumption of 1.5 kWh per day, an energy storage capacity of:
● 2 kWh - will provide power for about 1.5 days,
● 3 kWh to provide power for 2 days,
● 6 kWh to provide power for 4 days,
● 9 kWh will provide power for 8 days.
As you can see, proper selection of their power and capacity is able to provide backup power supply even during several days of network failures.
Additional conditions for an solar home battery system facility to be used as an uninterruptible power supply
To use solar home battery system for emergency power, it must meet three basic conditions that also affect its price. The first is that the devices will operate when the grid is not working. This is because, for safety reasons, both photovoltaic installations and batteries in many countries have anti-spike protection, which means that when the grid is not working, they do not work either. Therefore, to use them in emergency situations, you need an additional function implemented by electronics that disconnects the installation from the grid and allows the battery inverters to draw power from them without patterns.
Another issue is that devices operating on the basis of lithium ion (li-ion) or lead acid batteries, must operate at full power even without the grid. Cheap models have it that in off-grid mode, their nominal power decreases and even by 80%. Therefore, battery backup power supply with their use is ineffective or creates significant limitations.
In addition, an interesting solution that allows unlimited use of solar home battery system is an electronic system that allows you to charge lithium ion batteries with the energy produced by the photovoltaic installation even in a situation of power grid failure. In this way, devices can be continuously powered by solar home battery system without any limitation in terms of number of days. However, such installations are more expensive than standard solutions.
To sum up, how much power is enough from the solar home battery systems depends primarily on what devices they are to power, what batteries they are equipped with, as well as their power and capacity, also important is the efficiency of batteries, which is influenced by the number of charging cycles. In addition, deciding to connect them to the photovoltaic installation, it is also worth taking care that they allow you to fully use them as backup battery power supplies. Thus, their installation will not only avoid unfavorable settlements with power companies for both homes and businesses, but also gives a guarantee of full independence in case of network failure.