How To Know What Size Solar Battery You Need?

If you have finally decided to get a residential solar battery system for your home - congratulations on taking the first step in becoming self-sufficient. Now the second most important thing is to determine the solar battery size you would need to power your whole house, even when there’s no sun out there - and this is where most people run short.

To know the correct size of the solar battery for your home, there are a few factors that you need to consider before ordering your first residential solar battery system. If you’re struggling to calculate the right size of solar battery bank, this article will help you with it. 

Let’s start,

What Size Battery Do I Need?

 

The size of the battery storage that’ll be beneficial for you will depend upon:

•  The household daily energy consumption
• The amount of excess energy your home solar power system generates
• The panel array size
• The amount of independence you want from the grid

How To Calculate Solar Battery Bank Size

 

If you decide to build an off-grid system, it’s recommended to size your system based on the month, in which the panels receive the least amount of sunlight. This way, you will have a sufficient amount of energy to power your home at all times. 

It may sound a bit challenging, but there are a number of steps that you need to follow when calculating the size of solar battery storage.

Step 1:

Determine Your Daily Energy Consumption

You can find this information easily in your electricity bill. Usually, it’s printed as your monthly kilowatt per hour output. Divide that number by 30 and then multiply it by 1000 to get the consumption in watt-hours.

Becoming aware of the amount of energy you actually use is the first and foremost step in determining your solar battery bank size.

Step 2:

Get an Estimate of How Many Days The Panels Will be Without Sun

You can easily go to any weather forecasting site and look up the annual average of cloudy days for your local area. This step is necessary to ensure that you’ll have access to solar energy throughout the year.

 

A residential solar battery system with a large battery bank is best suitable for areas with more cloudy days, while a smaller one would be sufficient in areas that receive consistent and ample sunlight throughout the year. It’s better to size up rather than down.

Step 3:

Know the Lowest Temperature The Battery Bank Will Experience

Again, you get the average low temperature of your local area online. As the temperature goes down, battery capacity (the number of amp-hours it can hold) is reduced and capacity increases as the temperature goes up. Knowing the lowest will help you decide the adequate capacity of the battery bank you need.

Battery Bank Sizing Table

The below table shows what size of solar system can provide maximum returns based on your daily usage.

Best Residential Solar System in Alice Springs

Glossary for this table

Maximising returns’ – refers to the largest battery bank size that can be installed which the solar system can charge up to full capacity at least 60% of the days of the year. The figures are for the largest recommended sizes, smaller ones can offer better returns 

 

# days of energy autonomy’ – denotes the maximum estimated number of consecutive days that a home can go without drawing energy from the grid. You can use this as an approximation of how self-sufficient your system will be. If you want to go completely off-grid, make sure you always have at least  3-5 days of energy autonomy built into your system

 

# days blackout protection’  –  denotes the amount of time that you’d be able to continue consuming energy in the event of a grid outage 

Your daily energy consumption	Largest recommended battery size for…	Solar system size
		2kW	3kW	5kW	7kW	10kW
5-10kWh	Maximising returns:	5kWh	4kWh	4kWh	4kWh	4kWh
	Maximising energy independence:	–	22kWh (3 days of energy autonomy)	35kWh (5 days of energy autonomy)	35kWh (5 days of energy autonomy)	35kWh (5 days of energy autonomy)
11-15kWh	Maximising returns:	4kWh	7kWh	9kWh	8kWh	8kWh
	Maximising energy independence:	–	–	40kWh (3 days of energy autonomy)	65kWh (5 days of energy autonomy)	65kWh (5 days of energy autonomy)
16-20kWh	Maximising returns:	3kWh	6kWh	13kWh	12kWh	11kWh
	Maximising energy independence:	–	–	–	55kWh (3 days of energy autonomy)	90kWh (5 days of energy autonomy)
21-25kWh	Maximising returns:	2kWh	5kWh	12kWh	16kWh	15kWh
	Maximising energy independence:	–	–	–	23kWh (0.77 days of blackout protection)	70kWh (3 days of energy autonomy)
26-30kWh	Maximising returns:	1kWh	4kWh	11kWh	18kWh	18kWh
	Maximising energy independence:	–	–	–	–	40kWh (1.5 days of blackout protection)
31-40kWh	Maximising returns:	–	3kWh	10kWh	17kWh	23kWh
	Maximising energy independence:	–	–	–	–	27kWh (0.7 days of blackout protection)

 

Conclusion

With the above information you can quickly decide what battery size would be optimal for your household. If you have any doubt or want to know about the government subsidies and best offers to buy a residential solar battery system, contact Oneroof Solar. They are renowned for providing the best residential solar system in Alice Springs and all the neighbouring cities. 

Order your solar battery and keep a check on  your energy consumption starting today!