9 JUNIO 2020
Battery calculation for an isolated Solar Energy system
ARTICLE - UNIVERGY SOLAR | By Javier Martínez, design engineer at Univergy Solar
A battery is an energy-storage system that transforms the energy stored inside into electric power by way of electrochemical processes.
ARTICLE – UNIVERGY SOLAR | By Javier Martínez, design engineer at Univergy Solar
In systems where there is no power grid, it is vital to store energy for when we do not have the sun’s resource to generate electric power.
A battery is an energy storage system that transforms the energy stored inside into electric power by way of electrochemical processes. This generation of electricity is produced by a movement of ions between positive and negative electrodes (anode and cathode).
Batteries for solar power systems can both extract energy as well as obtain energy. This is achieved by simply reversing the chemical process as we apply an electrical charge or when extracting it from the battery.
How can we determine if our battery is correct for our solar power system?
The first thing we need to know is the type of battery we are going to use. The most common for solar power systems are the following:
- LEAD ACID
- AGM (these are also lead-acid but with a different configuration)
- GEL (because they have a type of gel inside)
- STATIONARY (OPZS) (for continuous use applications, ideal for solar power systems)
- LITHIUM (like those used in cell phones or laptops, but larger).
It is important to know the type of battery, given that it defines the depth of discharge (DOD) or how aggressive we can be when drawing energy from the battery.
To be able to calculate our system, we must start with the consumption (kWh energy) in order to determine size; it is also important to know the total power (kW), since this will be the maximum consumption peak that can be produced instantly in this power system.
With the above data, we must apply the following formulas obtained from the Technical Specifications for Off-grid Systems.
To find out how many solar panels to install:
This will give us the result in kilowatts to install per panel.
To find out what battery capacity we need to install:
In this case, we must find the value of C which is the battery capacity in amps hour (Ah).
With this data, we will now move on to select the components for our photovoltaic solar power system, panels, inverters, chargers, load regulators, battery capacity…
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