Solar power is one of the very best things you can invest in as a homesteader. Assuming the weather cooperates, you can count on the sun’s endless energy always being there for you. It’s a great way to go off-grid or just cut down on everyday usage.
But planning your solar array to accommodate your lifestyle and requirements can be tricky and requires some math. Let’s look at one of the higher-output solar panels out there, 300 watts. What can you run with a 300-watt solar panel?
A 300-watt solar panel can run a variety of high-drain devices and appliances. In the kitchen, this means things like coffee makers, toasters, stove tops, blenders, and electric kettles. You can also run personal electronics like gaming consoles, laptops and PCs, printers, routers, and more.
A 300-watt solar panel is a big step up in capability compared to 200 watt and 100 watt models.
If you have energy-hogging electronics and appliances you want to keep online, or just want to go on living as you always have even when you are off-grid or municipal power is out, 300-watt panels are definitely the way to go.
There’s a lot more you’ll want to learn, though, so keep reading and I’ll tell you everything you need to know to start harvesting that sunshine…
What are Some Things I Can Run on a 300W Solar Panel?
You can run a lot of stuff on a 300-watt solar panel, assuming, of course, that you have your power management system and batteries all in order. Check out the following table, but note this isn’t everything that you can run with it!
| ✓ Security Camera | ✓ Portable Fan |
| ✓ Clothes Iron | ✓ Wi-Fi Router |
| ✓ Coffee Maker | ✓ Ceiling Fan |
| ✓ Microwave | ✓ Printer |
| ✓ Clothes Washer | ✓ DVR Player |
| ✓ Stove Top | ✓ Game Console |
| ✓ Blender | ✓ Power Tools |
| ✓ Hair Dryer | ✓ Space Heater |
| ✓ Electric Shaver | ✓ Small LED TV |
| ✓ Cell Phone Charger | ✓ Laptop, Notebook, or Netbook |
| ✓ CRT Monitor | ✓ Vacuum Cleaner |
| ✓ Battery Charger | ✓ Small Speakers |
| ✓ Desktop Computer | ✓ Satellite Dish |
| ✓ Alarm Clock Radio | ✓ Toaster |
| ✓ LED/CFL Bulbs | ✓ Aquarium Water Pump |
| ✓ Cordless Phone | ✓ Electric Kettle |
| ✓ Satellite Receiver | ✓ Flashlight Charger |
What are Some Things That Won’t Run on a 300W Solar Panel?
As capable as they are, a 300-watt solar panel can’t handle everything, though this is usually limited to the most energy-intensive large appliances or fixtures in your home. Look into alternatives, or plan on seriously upgrading your solar system if you have to keep any of the following going.
| ✘ Clothes Dryer | ✘ Induction Cooktop |
| ✘ Well Pumps | ✘ Home Theater Systems |
Solar Panels Deliver Power Over Time, Not All At Once
If you’re new to solar power, this can all seem very overwhelming. Will you only be able to run certain things when the sun is out? Or when the sun is out on a clear day?
No, not exactly! For most of the things on the “okay” table above you couldn’t run them with a solar panel even in ideal conditions without the benefit of power management technology of one kind or another.
That’s because solar panels generate power relatively slowly and over time. This is usually calculated as a function of their stated wattage, and in this case, 300 watts, over a time scale, typically hours.
Said another way, your 300-watt solar panel doesn’t crank out 300 watts of instantly available electricity on demand when you flip a switch or plug in. It’s not like the usual power grid you’re thinking of, or a generator!
Instead, assuming conditions are right, you’ll get 300 watts of power generated, in total, every hour of sunlight that it absorbs. Does that make sense?
This means that in a single hour of ideal daylight conditions, your 300-watt panel will give you a net total of 300 watts of usable electricity. In 2 hours, you’ll have 600 watts. In 4 hours, 1200 watts.
A whole day of sunshine, assuming it is full-value sunshine, at 8 hours will give you 2400 watts.
Batteries are Needed to “Bank” the Generated Electricity
Since these panels don’t create their stated wattage instantly and make it available on demand, how are we supposed to power these high-drain devices I listed on the table up above? Easily: we need to store that power using a battery, or a battery bank.
This serves as a reservoir, or source, of stored electricity that we can then use with all of our devices and fixtures in our home, assuming of course we have our home wired up to the battery or can plug our gadgets and appliances into it directly.
In a way, it’s exactly like drawing water from a tank. If you have a hose or pressure washer that uses water and have it stored, you can draw water directly from that source. And, carrying on that analogy further, that pressure washer, hose, sprinkler, or whatever will use or consume a certain amount of water over time.
That consumption over time is the next thing we need to talk about if you really want to put solar panels to work for you.
Understanding Watthours is Key
The power requirements of your devices, fixtures, and anything else that is going to draw electricity from your power bank will determine how long your power will last.
- High-drain devices will use up your electricity more quickly.
- Low-drain devices will use it more slowly.
- Using multiple low-drain devices could drain it quite quickly.
- Using multiple high-drain devices could leave you on empty in no time!
So how do we figure this out? Simply enough, figure out the running wattage of your appliance, device, gadget, tool, or whatever. This is easy enough to do by consulting the manual, manufacturer’s info plate, or contacting the manufacturer directly.
For instance, let’s say you have a desktop PC that uses about 100 watts of energy per hour and a monitor that goes with it using about 30 watts per hour. And, of course, you’ll need internet which means you need a router online. They use an average of about 10 watts per hour. Total that up and you have 140 watts per hour demand.
Assuming your battery bank has the capacity and your 300-watt panel had ideal conditions all day, call it 8 hours, you’d have 2,400 watts of stored electricity. We then simply divide the total watts per hour, or watt-hours demand against how much power we have stored.
Dividing 140 into 2,400, we get a result of 17.14, meaning we have a hair over 17 hours’ worth of computer time on hand, or a little less than a whole day.
You can change this formula and figure out your requirements easily enough by adding or taking away the running wattage of all the different fixtures, appliances, and so forth.
Light bulbs, phone chargers, toasters, microwaves, etc., all have an associated cost that should be deducted from your power budget.
Weather and Other Conditions Make a Difference
Now, everything we’ve talked about to this point is the nominal output of a 300-watt panel. It assumes the panel is in good repair, clean, and has bright, clear skies and full-value exposure to sunlight.
Naturally, out here in the real world, things are often not ideal. Improper alignment, damage, wear and tear, and weather, including atmospheric dust and debris, can reduce somewhat the overall output of your panel.
This is an entirely separate conversation unto itself, but it’s something to keep in mind if you are counting on squeezing every last watt from your system for whatever reason.
Good controllers and other management technology can give you a readout on how much power is actually being generated hour to hour.
For this reason, it’s often a good idea to invest in a slightly larger or more capable system than you think you’ll need so you don’t have to split hairs when it comes to your electricity budget.
Device and Appliance Consumption Varies!
One more thing to complicate matters even further: every kind of device out here, and I’m talking about different makes and models of the same thing, have different power requirements.
This could be due to differences in materials, more or less efficient designs, additional capability, etc.
Estimates for a given deivce are good for initial planning, but it’s up to you to get down to the brass tacks and figure out exactly what your appliances and other gear require. That’s the only way to truly plan effectively.
Some examples of typical power requirements for a few common items are below This will at least give you a good estimate of what’s possible using a 300-watt solar panel.
Cell Phone / Tablet Charger
These devices usually have extremely energy-dense batteries, but the chargers themselves are more efficient than you might think.
If you leave the device plugged into your system while it’s not charging, it will still nibble away at your energy reserves at a rate of 0.1 to 0.5 watts per hour. Once actually charging, expect it to consume anywhere from 2 to 6 watts.
Using those figures, we see that we can charge an awful lot of modern smart devices using a 300-watt panel alone! Unless you’re redlining your system, you won’t have to worry about charging while you do other things.
Space Heater
While electric furnaces have power consumption rates that are usually measured in kilowatts per hour, and so are out of the question for anything but the largest and most capable solar systems, space heaters are another story. They are still quite energy-intensive, however.
Typical radiant space heaters will use around 1,500 watts of energy every hour. Using our example above of a 2,400-watt reserve of energy, you’ll only have a couple of hours of use if the system isn’t actively charging. You might want to look at other means of heating your space!
Electric Stove Top or Griddle.
These appliances are highly variable in terms of consumption, typically using anywhere from 900 watts to over 3,000 watts per hour, though this varies as the element is alternately turned on or off to maintain a steady cooking temperature.
It’s possible to run one using a 300-watt panel in the example given above, but it is going to gobble up some electricity. If the system isn’t charging, you might only get two and a half hours out of an average element set on medium. A single 300s-watt panel alone cannot deliver enough power to run even a single one of these devices; you’d need multiple panels, a much larger array, to directly power one.
Coffee Maker
Let’s get real; do we even want to go on living if we can’t have coffee when off the grid? I didn’t think so, so this is important.
Coffee makers and percolators are appliances with radically different requirements depending on the type and maker. And also remember that the longer they run the more power they use.
A good rule of thumb is to account for your coffee maker using anywhere from 700 to 900 watts every 10 minutes. A 300-watt panel can handle this easily as long as you aren’t brewing coffee continuously throughout the day.
CFL Light bulbs
Say what you want about government overreach when it comes to mandating these things, they are way more efficient compared to older incandescent bulbs.
Consumption is based on output, or lumens, but they typically use anywhere between 10 and 15 watts of power an hour. Remember, this is per bulb!
Leaving lights on can really nibble into your energy budget, so use only what you need and turn them off the moment you aren’t using them if you are relying on solar power. Turns out Dad was right when he was always screaming about lights being left on…
Tom has built and remodeled homes, generated his own electricity, grown his own food and more, all in quest of remaining as independent of society as possible. Now he shares his experiences and hard-earned lessons with readers around the country.
Find out more about the team here.