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Circular saws are among the most popular power tools for home improvement. But what inverter size would you need to run it efficiently? Just like with any power tool this depends on the specs and how you intend to use it. But a good sized inverter can do the job.
A 3000 watt inverter can run a standard 7 1/4″ circular saw that requires 1200 running watts and 2400 starting watts. A 5 1/2 saw will use less running watts, but you should not settle for anything less than a 3000 watt inverter due to its starting power requirements.
Circular Saw Inverter Power Consumption
Circular saws come in different sizes and types, but the most commonly used are 5 1/2 and 7 1/4 inches, referring to the blade size.
Most circular saws need 2500 watts to start up and 1200 watts to run, so a 3000 watt inverter is ideal. Technically a 2500 watt inverter is enough, but there should be reserve capacity in case of a power surge. Our top choices are the PowerDrive PD3000 Power Inverter which comes with Bluetooth, or the Renogy 3000W Pure Sine Wave Inverter.
The calculation expression is:
Total watt consumption + 25% = inverter size
or like this:
Amps drawn + 25% = inverter size
Power consumption is measured two ways, by watts or amps drawn. Check the saw specs sheet and you should see how many watts and amps the tool requires. Using that info you can determine what inverter is suitable for it.
Here is a quick guide on what inverter size to get for a particular circular saw size.
|Circular Saw Size
|Makita 5 1/2″ Circular Saw
|Festool 6 1/2 Circular Saw
|Ryobi 7 1/4″ Circular Saw
These are just examples, because the specs could vary widely depending on the manufacturer. There are some 7 1/4″ circular saws that run on 900 watts. At the other end are tools like the Hitachi C7YAH that requires 1680 running watts and 3360 starting watts.
Some circular saws only list the running watts, not the starting watts which is higher. A safe assumption is that the startup watts is double that of the running wattage. If wattage is listed at 1200 watts, assume that the starting or surge watts required is 2500 to 3000 watts.
A 3000 watt inverter size is only for the circular saw. If your shed runs on solar power and the inverter runs other devices, you will need more than 3000 watts. Calculate how many watts you use plus the circular saw to find the right inverter.
How Long Will My Inverter Run a Circular Saw?
It depends on what type of power system you are using. An inverter can be used on the grid or off the grid.
Figuring out how much power a circular saw uses can be tricky because you do not use it continuously. Unlike a fridge, power tools are run for a few minutes then halted, used again, stop and so on.
So while a circular saw may require up to 1200 watts an hour, it will probably end up consuming less than that. If you used the saw for 30 minutes in a 60 minute span, that would be 600 watts only. Now if you run it for less than that, power usage could be 300 watts. Of course if you use the saw for 45 minutes, it would be closer to 1000 watts.
If your inverter is on the grid, it can use electrical power. You can run a circular saw or any power tool for as long as needed. This applies not just to power tools but any appliance.
But if the inverter is off the grid, use a cordless circular saw instead. These tools run on batteries and can run for several hours depending on the usage. Most power tools are available in cordless versions, so get these instead if you are not on any grid tied system.
It does not make sense to run a circular saw from solar batteries like lead acid, lithium or AGM. For one, most power tools are designed to run on 115V or 120V AC power. Second, they would require too much battery power to run from a battery bank. You are better off using the battery to run appliances and a cordless saw instead.
What Type of Inverter Should I Use For a Circular Saw?
Once you know what inverter size to get, you have to choose between a pure sine or modified sine wave inverter. While pure sine wave inverters are more expensive, they are worth the price for circular saws and other power tools.
A pure sine wave inverter draws amps as if you are using the grid, and they can reduce energy losses significantly. A modified sine wave inverter is cheaper but they do not handle motors well.
The rule of thumb is modified sine wave inverters are good for electronics only, while pure sine is for electronics and motors. But even that is no longer necessarily true as many electronics are optimized for pure sine wave inverters.
How Many Solar Panels Do I Need to Run a Circular Saw?
If you want to run a circular saw on solar panels, it must produce the same amount of power that your inverter does. Even if it can, solar panels are not really a practical choice, though it is doable.
At least ten 300 watt solar panels are needed to run a typical 7 1/4″ circular saw. With ten PV modules it can generate 3000 watts an hour, enough to start the saw and run it. However, you can only use the saw during a clear, sunny day. If the sun sky gets dark or it rains, power supply will be interrupted.
Another thing to point out: most circular saws run on AC power so you cannot connect it to a solar panel. A direct connection is possible if it is a DC motor. But many circular saws run on AC, and they should not be connected directly to solar panels.
if you have plenty of space and the sun is out, you can use a solar array. You would probably get 5 to 7 hours of sun depending on your location. As the afternoon sets and the sun goes down, solar output drops though.
Tips For Using a Circular Saw with an Inverter
If you are still not sure what inverter to use for a circular saw, here are some suggestions to ensure that you get the right one.
Amps, Watts and Volts. inverter capacity is measured in watts while circular saw power in amps. Multiply amps x volts to find its wattage. For example, a 15 amp, 115V circular saw uses 1725 running watts (15 x 115 = 17025). Rounded off that is 1800 watts. Double that to 2600 and you have the starting watts. A 3000 watt inverter is perfect.
Get newer circular saw models. These are more energy efficient than older units. Older power tools have triple or higher starting watts than running watts. They are not practical for modern inverters.
Use a pure sine inverter. This was mentioned earlier but needs to be stressed. The price difference between pure and modified sine is significant. But the fact is a lot of power tools will not even run on modified sine wave inverters.
More power is better. If you are going to use several power tools you will need more than a 3000 watt inverter. That inverter size could run a circular saw yes, but if you include a drill, orbital sander and others they will use up power quickly.
Buy from a quality inverter manufacturer. The inverter is the most delicate part of any solar system. It is the one that is most likely to break because it undergoes a lot of stress. This is one reason why we suggest you not run it to full capacity but have several hundred watts in reserve.
Buy a quality circular saw. Even the most effective inverter will run poorly with an inferior tool. Look for a circular saw that is designed to run on inverters. There are several well known manufacturers out there that you can rely on for these types of power tools.
If you are going to use circular saws or any power tool, it will always consume a lot of power. Whether you are going to run it on electrical power or a battery and inverter system, make sure there is sufficient capacity available, and some reserve as well. This will ensure you will not run out of power while doing work.
I am an advocate of solar power. Through portablesolarexpert.com I want to share with all of you what I have learned and cotinue to learn about renewable energy.