As an Amazon Associate, this site earns commissions from qualifying purchases. For more details, click here.
Microwaves appeal to boondockers and those who live off the grid or in RVs for many reasons. They are compact, affordable and easy to use. But if you have a 100W inverter, can it run your microwave? At first, 1000 watts seems sufficient, but in fact, it is not enough for a 700 watt microwave.
A 1000 watt inverter cannot run a 700 watt microwave because the microwave uses up to 1200 watts to cook or heat food. The microwave needs 700 watts to start, but when in use requires much more power, so in this case, a 1200 or 1500 watt inverter is needed.
How to Find Microwave Solar Power Usage
Microwave solar power use is calculated this way: watts x time = energy used by microwave
Microwave power requirements range from 600W to 1200W. However, a 600W microwave and a 1000W microwave will use the same amount of solar power because of the cooking time.
Food that takes 5 and a half minutes to heat or cook on a 700W microwave is equivalent to 231,000 joules. On a 1100W microwave, the same food takes 3 and a half minutes or 210 seconds.
330 seconds x 700W = 231000 joules
210 seconds x 1100W = 231000 joules
Unlike a solar heat lamp which uses little power, microwaves can consume more than what the specs indicate. If a microwave is labeled 700W, that refers to the energy required to start the appliance.
The watts needed to cook food will be higher, which is why a 1000W inverter will not work. The easiest way to find out is to use a watt meter while running the microwave. Do not be surprised if the readings show 1000W+ even though it is rated at 700W only.
Keep in mind too that microwaves have different efficiency levels. The food you cook or heat also determines wattage use. Some of these microwaves may register 1000W, but others could be higher or just under 900W.
What Inverter Size For a 700W Microwave?
A 1200W inverter is enough to run a 700W microwave, though 1500W system like the Energizer Power Inverter better. However there are other factors that you have to consider before buying an inverter.
What Else Will be Running with the Microwave?
A 1200W inverter is for a 700W microwave, and only that. If you want to run a blender, that is another 400W. And if you want to use other appliances on solar power, you’ll need more than a 1200W inverter.
Decide what appliances you will use with the microwave and make sure to account for their running and starting watts. You may want to watch some TV while waiting for the food to heat up, or maybe turn on that coffee maker. Add up the watts and you get an idea of the inverter size.
For instance, you may want to run a coffee maker with your microwave while checking your laptop. Assume the coffee maker is 600W and the laptop is 100W. Add the 1200W for the microwave and that is 1900W. A 2000W inverter can all three appliances, but you should get a 2500W inverter instead so you do not push the system to the limit. Here is an in-depth guide about inverter sizes and how many appliances you can run with them.
Pure Sine Wave vs. Modified Sine Wave Inverters
There are two types of inverters, pure sine wave and modified sine wave. Modified sine wave inverters are cheaper but have a higher energy loss rate. Pure sine wave cost more but stores energy much better.
For light bulbs and small appliances, modified sine wave inverters are acceptable. But for microwaves, solar air conditioning units and high energy toasters , pure sine wave is ideal.
The larger the appliances, the more energy losses become critical. You need the most efficient inverter to maximize solar power, and that is what pure sine wave is for. A lot of new appliances are designed to run on pure sine wave inverters too. The Renogy 3000W Pure Sine Wave Inverter can run even the most power hungry microwaves without problems.
You can still use them on modified sine, but it won’t be as efficient and might not be good in the long term. It is better to invest in a pure sine wave inverter to ensure your microwave and other appliances run at optimum power.
With solar panels the reserve power recommended is around 20%-25%. For inverters the range is greater, from 25% to 100%. it really depends on how much power you need. The best way to find out is to observe your daily power use.
Just use the microwave and other appliances like you want to, then calculate the wattage. When you have the total, add at least 25% to the total and you have an ideal inverter size. Of course you should make adjustments in case your power requirement needs change.
Solar Battery Bank For Microwave
A 700W microwave requires at least a 300ah 12V battery. A larger battery is required if you are going to use other appliances alongside the microwave.
Battery capacity is measured in amp hours (ah). To convert amps to watts:
amp hours x volts = watts
watts / volts = amp hours
300ah x 12V = 3600 watts. Lead acid batteries only have a 50% usability rate, meaning at 50% you have to recharge it. So that 3600 watts is really 1500 watts, which is enough for the 1100 or 1200 watts your microwave requires.
If you are going to use other appliances as in the scenario mentioned earlier (laptop, fan, blender etc.), a 300ah battery is not enough. Just like with the inverter, calculate how many batteries you will need to go with your inverter. Remember to double the result if you use lead acid batteries because only half is usable per charge.
If you use a 700W-1200W microwave and a 600W coffee maker, that is 2000W. Solar panels cannot produce energy without sun, so if you want to use these appliances nightly, your battery bank must have at least 2000W available.
Note the 50% discharge rate is for lead acid batteries like AGM and gel. For lithium batteries you can run them for much longer. The actual number varies by manufacturer so check the company website for the specs.
An inverter draws power from the battery when it runs, so the battery bank has to meet the power requirements. Careful and thorough planning is a must, and you have to make allowances in case you suddenly need to use another appliance.
Factors to Consider For Using a Microwave with Inverter
1000W Inverter is Not Enough
There are not a lot of microwaves less than 700 watts. And if there are, they will not be as efficient in cooking so you will end up using fit or longer periods. In other words you end up using the same amount of energy, around 1100 to 1200 watts.
The easiest solution is to buy a bigger inverter. A 1500 inverter can run a microwave easily, and if you really want to go all in, there are 5000W inverters available that let you power a lot of appliances and devices.
Theoretically, is it possible for a 1000W inverter to run a 700W microwave? Yes. Some people say they can use a 1500W inverter with a 1000W microwave. The inverter may run, but over time the system will falter and might even damage the microwave. Do not take the risk and just purchase a more powerful inverter.
Lithium vs. Lead Acid Batteries
Lithium batteries can cost twice as much as lead acid, but their discharge rate is higher. You can use 70% or more of the battery before recharging. In contrast you can only avail of half the capacity a lead acid battery has. You have to buy twice the amount of amps needed because each is 505 usable.
If you only run the microwave for a few minutes a day, a lead acid battery bank may be enough. But if you have a lot of appliances hooked up to the system and want maximum mileage, better invest in a lithium battery.
This will be important for RVs. You have to maximize the space available so look for a microwave that is not only energy but space efficient too. The good news is a lot of microwaves now are built with space saving features without compromising power. Weight is important too, though your kitchen countertop should have no problems handling it.
There should be no problems running microwaves on solar power. That being said you want to make sure that the warranty has good coverage. Also check if it is designed to run with specific types of inverters. Even if does not say anything, the wattage should give you an idea of what inverter to use.
Whether you are off the grid, grid tied or living in a mobile home, the microwave has become indispensable. It just makes life easier, and with the right inverter size, it can work. Unfortunately a 1000W inverter is not enough, so get a 1200W or 1500W inverter, that should be enough.