An inverter is a device that uses DC power to convert solar energy into AC. It’s commonly used to convert solar energy into electricity.
Divide the inverter’s watts by the battery voltage to get the amps, and then divide the result by the inverter efficiency rating to get the runtime.
How To Calculate How Long A Battery Will Last On An Inverter
The battery’s capacity and power load are the two factors that determine the longevity of an inverter.
Watt load / volts = amps
Amps / inverter efficiency percentage = amps
Amps / available battery amps = inverter runtime
Using this calculation, a 24V inverter with a 100ah battery and 93% efficiency can run a 500W load for 2.3 hours.
How long can a 24 V inverter with a 150ah deep cycle battery, at 700 watts and 93% efficiency?
700 watts / 24 volts = 29.1 amps
29.1 amps / .93 = 31.2 amps
75ah / 31.2 = 2.4
After testing, the inverter was able to run a 700W load for 2.4 hours. However, since the battery’s discharge rate is only 50%, it only has a 150ah capacity.
If you have a new battery, you can usually reach 70% discharge rate without damaging the unit. Just replace the usable amps with anything that works for your battery.
Inverter Efficiency Rating
The efficiency rating of an inverter is a key factor that determines how much electricity it can convert from DC to AC.
There are two types of inverters, pure sine and modified sine waves. The former has a higher efficiency rating and is ideal for high powered loads.
Pure sine waves are commonly used for low-power loads and modern appliances. On the other hand, modified sine waves are good for high-power loads.
Note that the efficiency ratings of pure sine and modified sine waves are different. The former has a higher efficiency rating and is better for high-power loads.
How Many Batteries Are Needed For My Inverter?
So if the inverter powers appliances using the battery, how many do you need? Well it depends on how long you want to run the load.
Let’s say that you’re planning on running a 1000W load for 4 hours. You’re using a 1500W capacity inverter.
To run the full 1000W load, the inverter will need four 100ah batteries. You’ll then need to make sure that the batteries have a 50% discharge rate.
Here is how we came up with these numbers:
100ah x 24V= 2400 watts
But only half of this can be used in a deep cycle battery, so:
2400 watts / 2 = 1200 watts
Factor the inverter efficiency rating and the available capacity will be around 1000 watts.
1000 watts is enough to run your load for an hour. To run it in four hours, you need four x 100ah 24V batteries.
If you prefer to use amps instead of watts, the formula is:
Total amps drawn per hour x operating hours + 100% = battery size
If the total power supply is 30 amps an hour, you need to run the load for 4 hours. You need 240ah deep cycle batteries to power the machine.
How Much Battery Reserve Is Needed?
The battery should be at least 50ah 24V to provide the maximum output of the solar array.
If you’re planning on using the inverter for multiple days, it’s recommended that you have a capacity of at least 3000 watts. This is to cover the day-to-day needs of the system.
On-grid systems are also known to work seamlessly without batteries. They allow you to generate and receive credits for the excess solar power.
If you’re not on the grid, then you’ll need a battery bank or a generator to recharge the inverter. However, if your RV is regularly used, then you don’t need to worry about this issue.
What Inverter Size Do I Need?
The capacity of the inverter should be at least 25% bigger than the amount of electricity that the system is designed to consume.
Total watt load + 25% = inverter size. If you are going to run a 400 watt load that would be 400 watts + 25% = 500 watts.
Of course, you can increase the capacity of the inverter, but only if you’re planning on needing more power in the future.
To increase the voltage of the solar panels, use 24V or 12V panels. You can also connect the various components of the system together to get the desired voltage.