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An inverter allows you to run appliances, tools and other electronic devices from solar panels. It converts direct current from the panels into alternating current (AC) so appliances can use it. So how many of these devices can you power on an 800W inverter?
An 800 watt inverter can run a 16 cu ft. fridge, a 32 inch TV, a 500W microwave and several light bulbs. To run these appliances in an off-grid system, you will need at least a 100ah battery.
How Many Appliances Can an 800W Inverter Run?
Inverter load capacity is measured in watts, so an 800W model like the WZRELB Pure Sine Wave Solar Inverter can handle up to 800 watts simultaneously. Most inverters also have a surge capacity twice its running load limit, so an 800W inverter usually has a 1600W surge watt limit.
The math is simple. As long as the total watts used by the appliances is 800 watts or less, the inverter can run it.
Here is the average power consumption of some popular appliances that an 800W inverter can handle. These are general guidelines only and you should always check the actual wattage of each appliance and device.
- LED light bulbs 10W
- 42 inch TV 60W
- Fridge freezer 80W
- Ceiling fan 70W
- Curling iron 35W
- Desktop computer 100-500W
- Electric blanket 200W
- Food blender 400W
- Laptop 100W
- Slow cooker 180W
- Small washing machine 500W
- Router 20W
For more on running appliances on solar power, do not miss this DIY guide.
The number of appliances an inverter can operate depends on their power consumption. As long as it is under 800 watts an hour, the system will be fine.
Using the examples given here, you can use a laptop, a ceiling fan, several LED bulbs and a freezer and with plenty of power to spare. You can throw in a TV, phone charger and other small devices too.
The more power hungry an appliance the fewer you can run simultaneously. For instance you can only use two food blenders at the same time. If you load a 500W washing machine there is only 300 watts left available.
Please keep in mind that some manufacturers do not recommend running inverters at full capacity. While inverters can load to their maximum limit, it is better to have some spare capacity in case of a power surge. This is similar to not overloading a power outlet.
How Long Will an 800W Inverter Last?
Inverter running times depend on the source. The system will run continuously provided there is enough power available. In the following examples we will assume you have an 800 watt inverter and using deep cycle batteries as the power source.
The formula is: ah (battery capacity) x battery voltage / watts
So assume you have a 100ah 12V deep cycle battery like Battle Boom. You want to run a laptop computer, a freezer, 3 LED light bulbs, a router and a ceiling fan. How do you figure out how long the inverter lasts?
First, add the total watts:
Ceiling fan 70W
3 light bulbs 30W
Now let use the formula given earlier:
100ah x 12V / 320 = 3.75
An 800 watt inverter powered by a 12V 100ah battery can run a 320 watt load for approximately 3.75 hours.
The steps above can be used for any battery capacity or voltage. Solar batteries are available in different sizes and voltages, but the calculations remain the same.
Other Inverter Runtime Examples
Take the same 320 watt load but this time you have a 12V 220ah battery.
220 ah x 12V / 320 = 8.25
A 320 watt load will run for 8.25 hours on the inverter. Compare this to a 100ah battery with a running time of 3.75 hours.
The greater the battery capacity the longer the run time. Of course if you increase the load from 320 watts to 500 or more, the runtime shortens.
You are probably wondering why we have not used 24V inverter batteries in these examples. The reason is 24V batteries are optimized for 1000W-5000W systems. This guide focuses on 800 watt inverters where 12V batteries are most suitable.
But if you have an inverter for example and a 24V 200ah battery, the formula is still the same. Multiply the battery capacity by its voltage and divide by the power load.
Again using the same 320 watt load in our previous examples:
200 ah x 24V / 320 = 15
A 320 watt load can run for 15 hours with a 24V 200ah battery.
This formula makes it easy to determine the estimated runtime of any inverter and battery. One thing to keep in mind is that these are estimates only. In general it is best to be conservative with the runtime.
So if the runtime you get is 6.5 hours, assume the inverter is good for 6 hours and 15 minutes at most. The reason is that some capacity is lost when an inverter converts direct current into alternating current.
Inverters have become more efficient, but you should still expect some losses. As noted earlier too, it is not a good idea to run an inverter at maximum load capacity. But with these calculations you can get a good idea of how much an inverter is really capable of.
How Many Batteries Does an 800W Inverter Need?
Inverter battery requirements are proportional to the load it will carry. The longer you want to run appliances the greater the battery capacity.
To figure out how many batteries an 800 watt inverter needs, add the total watts. Next, divide the battery capacity (ah) by its voltage. The result is its watt capacity.
In the following examples we will use an 800 watt inverter, but you can replace this with any inverter size and use the same steps.
You want to load several appliances totaling 600 watts and run it for 6 hours. How many batteries will you need?
600 watts x 6 = 3600 watts
First you have to figure out the watt capacity of the battery Assume you picked a 12V 100ah battery.
Battery size is measured in ah (ampere hours). To convert this into watts, multiply it by the voltage. So with a 100ah 12V battery:
100×12 = 1200 watts
A 100ah battery has a capacity of 1200 watts. Your load is 600 watts, but deep cycle batteries should not be completely discharged. Even most lithium batteries should be recharged when capacity drops to 15-10%.
If a lithium battery has an 85% discharge rate, its capacity is about 1000 watts an hour. You need 4×100ah 12V lithium batteries to run a 600 watt load for 6 hours.
This calculation assumes the battery has a usable capacity of 85%. Lead acid batteries have a 50% discharge rate so you can only use 50ah at a time.
50×12 = 600, so to run a 600 watt load for 6 hours you need 6×100ah lead acid batteries. Before you decide what battery to use with your inverter, check its discharge rate. That tells you how much power is actually available.
How Many Amps Can an 800W Inverter Draw?
If you load 800 watts onto a 12V 800 watt inverter, it will draw 66.6 amps. Divide the total wattage by the voltage and you get the amps drawn.
Only the watts consumed should be used, not the inverter capacity. If you have a 600W inverter but only carrying 350 watts, use 350 in the calculation.
350 / 12 = 29.1
This is the same method to use for any inverter or battery. Because most appliances use watts, that is what we usually look for and calculate.
But there may be times when you have to figure out how many amps the inverter draws. In this case you can see, the steps are straightforward.
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