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How to build battery bank by using deep cycle batteries for solar power system

Table of Contents

What is solar power system ? and are Deep Cycle Batteries batter for Power bank?

there are 4 major types of solar power system according to its application – on grid solar, off grid solar, and hybrid solar power system.

1) On grid – solar farm

It is solar power plant, also called “solar farm”. This is mega-watt huge solar power system works as a power plant to generate electricity to publics or private use. Solar panels connect to DC- AC inverter and send electricity to the AC grid. In most cases, it doesn’t need any battery as energy storage since all solar energy is sent to grid.

2) On grid – net metering

It is home or office size solar power system. On Grid – net metering system can save your electricity bills. AC loads are directly supplied by solar power instead of grid. When solar panel generate more electricity than demand of AC loads, those surplus solar energy will be sold back to grid.

3) Off grid

This is independent stand-alone solar power system without connecting to AC grid. Our LWI high performance gel deep cycle solar battery can provide long service life for off-grid solar power solution. Off-Grid solar power system gives you completely self-sustainable solar energy anytime, anywhere.

4) Hybrid

Hybrid solar power system combines the advantages of “On Grid net metering ” and “Off grid” system. AC loads are supplied by solar power directly, the surplus solar energy can be used to charge batteries or sell back to grid. The batteries are charged by AC grid in cloudy day and night. Battery can be used to supply AC loads in day or night whenever grid electricity rate is expensive. AC loads also secured by LWI high quality gel deep cycle batteries when grid is failure (blackout).

What is battery bank for solar power system ?

After understanding 4 major types of solar power systems, let’s talking to battery bank. The battery bank means several batteries with parallel and series connection set up into an energy storage bank, which store solar energy from solar panel and provide electricity to loads via DC-AC inverter. Battery bank is core item in a solar power system as an energy storage.

What is the difference between a Standby battery and a deep cycle battery ?

First, we should talking about the application of battery Generally speaking, there are two major application of industrial battery : standby use and cycle use.

  • Standby use – emergency power backup for UPS, telecom base station, and security system. Battery is always fully charged and in standby condition as a power backup, the battery are used only when grid power failure, the battery power supply AC loads via DC-AC inverter during blackout.This kind of battery are being used, technically called “discharged”, only several times a year, the most of time they are just waiting and standby. When battery is being used as a power backup, it usually will not be deeply discharged. People are focus on its “standby life” than “cycle life”
  • deep Cycle use – power source for e-scooter, e-mobility, e-bike and renewable energyBattery is always being used every day as a power source. We call it “one cycle” when battery being fully charged and deeply discharged once.This kind of battery as a power source, it is expected to provide as much power as possible to extend the usage time, so it is usually being deeply discharged to provide more power. People are focus on its “cycle life” than “standby life”. Those batteries are designed for deep cycle applications are called deep cycle battery.

Why should we use deep cycle batteries for solar power system ?

Obviously, battery in a solar power system is being charged in daytime by sun and discharged in cloudy day or night. Battery is acting as a solar energy storage device, it reserve solar power in sunny time and provide power in raining time or night. So solar battery is always being fully charged and deeply discharged. We should choose deep cycle batteries for battery bank of solar power system.

How many battery should I have for my solar power system ?

it depends on how much AC loads, which are usually home electric appliance and how long they will be powered by batteries. For example, if you have 1500W AC loads and need to be powered by batteries for 3 hours. The calculation is :

1500W x 3 hours = 4500Wh, which means you need 4500Wh battery capacity If we use 12V 150Ah gel deep cycle batteries, ( Gel link ) The single battery capacity is 12V x 150Ah = 1800Wh 4500Wh / 1800Wh = 2.5, so we need at least 3 pcs battery to support AC loads.

However, the solar inverter system for household use is usually 48V system, It means solar panel and battery bank should be 48V. Single gel deep cycle battery is 12V, so we need a multiple number of 4 which make it into 48V system by series connection. In above case, we need to use 4 pcs 12V 150Ah batteries for the battery bank

What should I consider before choosing battery ?

There are several factors that should be taken into account when determining the total cost over the life of the battery.

  • Battery Price: low price is always attractive, but if low price comes at the expense of quality and battery life, the need for frequent battery replacements could boost the cost over time.
  • Battery Capacity: Capacity is important because it’s a measure of the amount of energy stored in the battery.
  • Battery Voltage: The battery bank voltage must be considered to ensure it matches the system requirements. The battery bank voltage is often determined by the inverter specifications if installing a DC-to-AC system or by the voltage of the loads in a DC system.
  • Battery Cycle Life: The most critical consideration is cycle life, which provides the number of discharge/charge cycles the battery can provide before capacity drops to a specified percentage of rated capacity. Batteries from different manufacturers may have the same capacity and energy content and be similar in weight. But design, materials, process and quality influence how long the battery will cycle.

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