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Power tools have become more sophisticated and versatile. At the same their power consumption has increased. If you want to run a jig saw or drill on solar panels, how many will you need?
1500 watt solar panels can run most drills and routers, but circular saws require at least 3000 watts. If you are going to use several power tools, a 4000 watt solar array with batteries is the ideal setup.
How Many Solar Panels Do I Need to Run Power Tools?
We cannot cover every power tool, so we will go with the most widely used for home improvement and workshops. And no matter what tool you use, the calculation will be the same.
Power tool watt usage + 10% (or higher) = solar panel size
Suppose you want to use a 5 1/2 inch circular saw. Its running watts ranges from 1500-3000, but for our example it is 1500 watts.
If the saw has 1500 running watts, its starting or surge power requirement is about 3000 watts. The surge watts is what it takes to start the saw. It takes a second or less but your solar panels must be able to supply this.
Because solar power varies throughout the day , add 10% as reserve.
3000 + 10% = 3333 watts
Rounded off to the nearest solar panel size, that is 3500 watts. So the solar panels must generate 3500 watts to run a 5 1/2 inch circular saw.
The circular saw will not consume the entire 3500 watts when you use it. As we pointed out, it only needs 1500 watts to run continuously. But your solar array must provide 3500 watts to start the motor.
Once the saw is running, it frees up the rest of the solar array for other uses. This is also how solar power tools work if you run them on inverters.
To generate 3500 watts you need several solar panels. An array consisting of 5 x 300W solar panels can produce 1500 watts an hour, enough to power a circular saw. .You can star off with the Renogy 300 Watt Solar panel Kit and then add another three 100 watt solar panels.
While solar power fluctuates, this array should be enough since you probably won’t be using the saw continuously for an hour. For assurance of course you can always go with 6 x 300W.
While 300 watts is the most common, you can try other sizes like 200 or 350 watts. As long as the total matches or exceeds the watts required by the power tool, the array will be fine.
Power Tool Solar Power Guide
The following table lists some of the most commonly used power tools and their watt consumption. There are many types of power tools, so if yours is not included, please refer to its operating manual. There are many types for each, i.e. drill presses have varying specs so you have to account for that as well.
|Power Tool||Amps Draw Per Hour||Watts Per Hour||Inverter Size|
|Circular Saw 5 1/2||12-15||1500-3000||4000W|
|Orbital Disk Sander||3-5||360-500||1000W|
|Small Angle Grinder||7-10||840-1200||2000W|
Two things need to be kept in mind when using the table above. First, these figures are estimates. The actual specs for your power tool might be different.
Second, the wattage is on a per hour basis. But power tools, like solar powered welders, are used intermittently so the actual usage per hour will vary. However you should have an idea of how often you use each tool.
You can also use this guide for running power tools on inverters or solar generators.
This brings up the question of which is better for power tools, solar panels or generators. A 3500 watt solar array usually costs less than a 3500 watt solar generator, and it is less bulky.
However, solar generators provide consistent power since they use stored energy. They are basically batteries and will run whether the sun is out or not. Of course if it is summer solar panels will provide consistent results too, so it is your call.
How Long Can Solar Panels Run Power Tools?
The answer depends on how much sunlight is available and how often you use the tool. It also depends on how many power tools you have to use.
A 2000 watt solar array can run a 900W jigsaw nonstop for about two hours. Even if the jigsaw needs 2000 surge watts, that is only for a second so there is sufficient power available.
If you only use the jigsaw for 30 minutes, the runtime goes up to four hours. Like with most power tools you probably use this for a few minutes to make a cut, then stop and use it again and so on.
Using the table above, it is easy to figure out how many watts a power tool requires and how long a solar array lasts.
In the next section we take a look at the various factors that affect solar power output. No matter what power tool – or any electronic load for that matter – you want to run, knowing what elements affect solar power is essential.
Factors That Affect Solar Panel Power Output
Solar panels can run just about any appliance or power tool, but everything depends on sunlight. Solar panels will cease to run once the sun goes down.
If there are 5 hours of sun available, solar panels will run for 5 hours. However the output will not be consistent. A 300 watt solar panel is not going to produce 300 watts for each of those five hours.
The reason is the sun changes position in the sky relative to the solar panels. If you keep an eye on the PV system display you will see that output is highest at noon and drops later in the afternoon.
So the more hours available the longer you can use power tools. Depending on the season and your location, you could get 6 to 8 hours, or maybe less than 5.
This is primarily the reason why we recommend having at least 10% reserve power. There are other factors that influence PV power production like shading, rating efficiency, size etc. But mainly it is about the sun.
How Many Batteries Do I Need For Power Tools?
Battery capacity is measured in amps so you need to figure out how many amps your power tools draws per hour. Use the table above or check your tool manual for the specifications.
A 100ah battery can run a 15 amp circular saw for 8-9 hours continuously. Deep cycle batteries (except lithium) should be recharged at 50%, so the runtime will be 4 hours.
If you want the 8 to 9 hour runtime, use a lithium battery or buy a 200ah AGM battery. With the Ampere Time 200ah Lithium Battery you get even longer running time.
Power tools and deep cycle batteries both use amps so it is easy to estimate the runtime. Remember that batteries discharge faster when more amps are used, so be conservative when estimating capacity.
The number of batteries needed depends on how long you intend to use the tools. List all the tools you will use and add the watts. With that as a guide you can determine how many batteries and solar panels are required.
With a solar array and battery bank you have different options for power tools.
- You can use the solar panels for the tools, and when the sun goes down switch to the batteries.
- Or you can charge the batteries with solar panel and run the tools off them. In this case you are using the solar panels as battery chargers.
The advantage with option two is the consistent power supply. Even if the sky suddenly turns cloudy, your power tools will still run.
You can use this same approach with a solar generator. Some generators can connect to solar panels for extra power, or you can just use AC power to charge the system. Either way, a solar generator works the same way as a battery bank.
Power tools require a lot of well, power. However, modern solar panels are up to the challenge. With a bit of planning you can set up a PV system that can run any power tools you need regardless of its requirements.