What size solar battery do I need

With every type of battery, its capacity and ability to deliver that energy is king, so what size solar battery do I need.

The answer is determined upon the value you place on the source of energy. Without a value, people will always go for the lowest cost. But the lowest cost in battery circles will not always provide what is needed. We have all seen low cost batteries in shops, more often than not we have in time purchased them. Only to find that they have a limit to what they will provide. Therefore it is important to understand the needs your battery project requires.

There are many hundreds of batteries that all say that they are better than others. In some cases this is true, but identifying this to the uninitiated is almost impossible. So the quick answer is not to grab at the lower cost, but to visualize the common denominator that separates the wheat from the chaff. As a company we offer deep cycle batteries from original equipment manufacturers. That way we can be sure of the quality and originality. True deep cycle batteries are able to withstand many hundreds of full discharges, without creating damage to the internal makeup of those batteries. Standard leisure type batteries will carry a certain depth of discharge multiplied by cycle life before they fail. This is something to investigate before making a purchase. Our range of deep cycle batteries can work constantly for longer periods and deeper discharge capacities than standard batteries. Therefore the ability to last four times longer must be more appealing to the customer.

Types of deep cycle batteries, AGM asbestos glass matt construction offer a non spill life time maintenance free design. Our choice for this type of solar battery would be the Victron super cycle battery, that are designed to last the following amounts of depth of discharge; DOD.

  • 300 cycles @ 100% DoD
  • 700 @ 60% DoD
  • 1000 @ 40% DoD

The Gel Deep cycle battery type maintenance free flat plate solar batteries are designed to last between 7-10 years extra long life versions. These provide exceptional discharge recovery when working under a wide temperature range. They work within the following DOD.

Rated capacity: 20 hr. discharge at 25°C
Float design life: 7-10 years at 20°C
Cycle design life:
400 cycles at 80% discharge
600 cycles at 50% discharge
1500 cycles at 30% discharge

The ultimate battery at this time is the Lithium. This provides a superior DOD, down to 5% in most cases with cycle life between 2,000 and 5,000 cycles making it a high performance unit. The lithium battery of choice for renewable energy systems is the lithium phosphate type (LiFePo4). This style of battery has the ability to discharge and recharge large capacities of stored energy without damage to the internal structure. This type of battery for smaller projects @ 12v or 24v are best using this product. Victron lithium battery | li-ion phosphate solar storage. The capacity is and technical aspects can be found here:

  • Save weight and physical size compared to traditional batteries
  • IP54 ready
  • Charge between 14v-15v
  • Float voltage 13.6v
  • -20C up to +50C
  • LiFePO4 safe to use li-ion batteries
  • Victron lithium battery is available in the following kW hour sizes
  • 50Ah = 0.64kwh capacity @ 12v
  • 60Ah = 0.65kwh capacity @ 12v
  • 100Ah = 1.28kwh capacity @ 12v
  • 160Ah = 1.8kwh capacity @ 12v
  • 200Ah = 2.56kwh capacity @ 12v
  • 300Ah = 3.84kwh capacity @ 12v
  • 200Ah = 5.12kwh capacity @ 24v

Should the project require a larger capacity battery, then this usually make life easer to increase the voltage to 48v. That way, the battery more stable for higher load capacities. These type of battery are usually used for home or household energy storage facilities. We call these On grid battery storage systems for home owners to store power. They range from 2.4kwh up to 15kwh capacity.

To measure the capacity of the battery required it is important to understand the load being placed upon it. A simple method is to multiply the energy requirement of power being used. This can then provide a starting point towards understanding the requirement.

If you are in any doubt, then contact us and we will assist your request. Contact Us – Dragons Breath Solar