How Much Energy Does a 100 Watt Solar Panel Produce?

I recently tested a 100 watt solar panel for 10 days to shed insight on how much energy solar panels can produce.

The results?

My 100 watt solar panel output an average of 431 watt hours per day. The total energy produced over the course of my test was 4.31 kilowatt hours (or 4,310 watt hours).

Based on my test, I’d say that, on average, a 100 watt solar panel will output around 300-500 watt hours per day.

But solar panel output varies considerably based on factors like location, shading, weather conditions, and time of year. For instance, over the course of just 10 days of testing, my panel had days where it produced as low as 50 watt hours and upwards of 600 watt hours.

Keep reading for my full test results, as well as snapshots of the solar panel’s power output at various points during the test.

Video

I made a video of my power output test to accompany this article. Check it out below and consider subscribing to my YouTube channel if you like DIY solar videos like this!

Test: How Much Energy Does a 100 Watt Solar Panel Produce?

To answer this question, I connected a Renogy 100 Watt Monocrystalline Solar Panel to a Victron SmartSolar MPPT Charge Controller. I also connected a Victron BMV-712 Battery Monitor to the battery to monitor its state of charge to ensure the battery never reached full charge or entered absorption mode. (If it had, the charge controller would have cut the output from the solar panel to prevent overcharging.)

I mounted the panel at the optimal tilt and azimuth angle for my location (Georgia) and time of year (April), and placed it in a sunny spot in my backyard.

With my setup complete, I connected the solar panel at midnight on Day 1 to make sure that, come sunrise, the solar panel was in position to collect every possible watt hour of energy.

With that, the test was underway!

Day 1

Weather

• Conditions: Sunny all day
• Highest temperature: 81°F (27°C)
• Lowest temperature: 39°F (4°C)

Power Output

At 1pm on Day 1, I recorded the solar panel outputting 94 watts. That’s actually great output from a 100 watt solar panel. Solar panels only output their rated power in ideal conditions, so seeing anything close to 100 watts from a 100 watt solar panel is great.

At 3:30pm, the panel was outputting 82 watts.

By 5pm, branches from a nearby tree had started shading the panel and it’s output had dropped to 13 watts.

At 7pm, the sun had almost set and the panel was heavily shaded. It was outputting just 2 watts.

Results

• Total energy produced: 590 watt hours
• Max output: 95 watts

Day 2

Weather

• Conditions: Sunny all day
• Highest temperature: 82°F (28°C)
• Lowest temperature: 46°F (8°C)

Power Output

At 10am, the solar panel was outputting 49 watts. Though it was in direct sunlight, it was generating medium output due to the low angle of the sun.

At 1:30pm, the panel was outputting 90 watts.

At 4pm, the panel was still outputting a respectable 76 watts.

By 7pm, the output had again dropped to just a few watts.

Results

• Total energy produced: 560 watt hours
• Max output: 95 watts

Day 5

Note: Days 3 and 4 were similar to Days 1 and 2, so I’m skipping ahead here. From now on, I’ll just include snapshots from days with different weather conditions.

Weather

• Conditions: Cloudy in the early morning, mostly sunny for the rest of the day
• Highest temperature: 81°F (27°C)
• Lowest temperature: 57°F (14°C)

Power Output

It was a little cloudy at 10:30am, so the panel was only outputting 20 watts.

At 1pm, I recorded the panel outputting a whopping 103 watts! That was the highest output I captured on camera for the entire test.

How can a 100 watt solar panel produce more than 100 watts?

Well, the conditions have to be just right. The panel can’t be too hot, because solar panels output less power as they heat up. And, of course, it has to be very sunny. What’s interesting is that this is what the sky looked like at the time I recorded the output of 103 watts:

It looks to me like the sun is reflecting a bit off the nearby clouds. This is actually a common phenomenon called the cloud-edge effect that can produce spikes in solar panel output. Pretty cool!

At 4pm, the panel was outputting 80 watts.

At 5pm, the panel was partially shaded and outputting 16 watts.

Results

• Total energy produced: 470 watt hours
• Max output: 105 watts

Day 9

Weather

• Conditions: Cloudy all day
• Highest temperature: 61°F (16°C)
• Lowest temperature: 55°F (13°C)

Power Output

Day 9 was completely overcast all day, so the panel’s output was greatly reduced. At 9:30am, it was outputting 7 watts.

At 12pm, the panel was outputting 21 watts. That’s more or less typical for a 100 watt solar panel on a very cloudy day.

At 2:30pm, the panel was outputting 7 watts.

At 6:30pm, the panel was outputting 3 watts.

Results

• Total energy produced: 90 watt hours
• Max output: 39 watts

Day 10

Weather

• Conditions: Cloudy and rainy all day
• Highest temperature: 63°F (17°C)
• Lowest temperature: 55°F (13°C)

Power Output

Day 10, the final day of my test, had terrible weather. It was dreary and overcast the entire day. And it rained on and off for half the day.

At 9:30am, I recorded an output of 2 watts.

At 12pm, the panel was outputting just 7 watts.

At around 1pm, the rain started. I checked the panel’s output at 1:30pm: 4 watts. Keep in mind, it was around that time just 5 days ago when I measured an output of 103 watts.

It was still raining at 3pm. At that point, the panel was outputting 7 watts.

And, for the last power output check of the entire test, I checked the panel’s output at 6pm. I measured 4 watts.

At 11:59pm on Day 10, I disconnected the panel, thereby ending the test.

Results

• Total energy produced: 50 watt hours
• Max output: 29 watts

Test Results

Here are the final numbers from my test:

• Total energy produced: 4.31 kWh (4,310 Wh)
• Average daily energy production: 431 Wh
• Highest daily energy production: 590 Wh
• Lowest daily energy production: 50 Wh
• Highest solar panel output: 122 W (I wish I had caught this on camera…that’s crazy!)

So let’s circle back to the question I posed in the title of this post: how much energy does a 100 watt solar panel produce?

Based on this test, this is how I’ll answer the question: a 100 watt panel will produce, on average, around 300-500 watt hours per day.

And to that already wide range I’ll add a big stinking asterisk, because the actual value can vary widely based on a variety of factors like weather, shading, location, and time of year.

As we saw during my test, on a perfectly sunny day my 100 watt panel produced upwards of 600 watt hours. And on a day where it was cloudy and rainy all day, it produced as low as 50 watt hours.

Factors Affecting How Much Energy Solar Panels Produce

I ran this test to get a general idea of how much energy a 100 watt solar panel produces on an average day. But how much energy your solar panel produces will depend on a number of factors, such as:

1. Solar panel wattage: Obviously, the bigger your solar panel, the more energy it will produce. The data from my test applies to 100 watt solar panels.
2. Shading: Solar panel output drops when even a small part of the panel is shaded. The more time your panel spends partially or fully shaded, the less power it will output.
3. Weather and temperature: How cloudy or sunny it is will have a big effect on solar panel output. Also, solar panel output drops as temperature increases.
4. Sunlight intensity: How much energy the sun outputs over a day — often referred to as “solar irradiance” or “solar insolation” — naturally fluctuates over the course of a year. You can use our solar irradiance calculator to find out how much sunlight your location gets. Sometimes you’ll hear a location’s daily amount of sunlight referred to as “peak sun hours”, which is a similar unit of measurement as solar irradiance. We also have a peak sunlight hours calculator you can use if you prefer those units.
5. Tilt and azimuth angle: There is an optimal angle to mount solar panels at depending on location and time of year. The direction you face your panel, known as the azimuth angle, varies by location and also affects output.
6. Soiling: The dirtier a solar panel is, the less power it will output. To maximize your panel’s output, it’s helpful to clean the panel regularly.
7. Location: Some locations and latitudes naturally receive more sunlight than others. Florida is sunnier than Alaska, for instance.
8. Type of solar panel: Monocrystalline and polycrystalline solar panels respond differently to temperature and weather conditions.
9. Charge controller or inverter efficiency: In DIY solar systems, the type (PWM or MPPT) and efficiency of your charge controller play a big role in how much of the solar panel’s power output gets sent to the battery. In residential solar systems, the efficiency of your system’s microinverters affects the overall output.
10. Wiring configuration: If you’re using multiple solar panels, how you wire them together affects their power output and how they respond to shading.
11. Battery state of charge: In off-grid solar systems, the energy your solar panel produces gets stored in a battery. Charge controllers monitor the battery voltage to estimate the battery’s state of charge, and, depending on that (plus the battery type you’re using), they will increase or decrease the solar panel’s output. For instance, when a battery is mostly charged, the charge controller will usually enter an absorption stage where it doesn’t use all of the available power output by the solar panel. The more time your battery spends mostly or fully charged, the more your charge controller will throttle the solar panel’s output.
12. Solar panel age: Solar panel output drops over time, so if your panel isn’t outputting as much as you’d like, it may be due to reductions in power output due to aging.

7 Ways to Increase Solar Panel Output

Now that we know the main factors affecting solar panel output, we can cover some of the main ways to increase it.

1. Move the solar panel to a sunnier spot: Shading greatly reduces solar panel output, so, before mounting your solar panel, pay close attention to which of your available mounting locations gets the most direct sunlight over the course of the day. If possible, move the solar panel.
2. Reduce shading: If you can’t move your solar panel, consider trimming branches or moving objects that cast shade on the panel.
3. Optimize tilt and azimuth angle: Use our free solar panel angle calculator and solar azimuth angle calculator to find the optimal angle and direction to mount your panel.
4. Clean the solar panel: Over time, dirt, pollen, bird droppings, and other debris may collect on your solar panel. Solar installer Palmetto recommends using warm water, dish soap, and a soft cloth or sponge to clean the panel glass every so often.
5. Add more panels: If a single solar panel isn’t cutting producing enough energy, you can buy another and wire the panels in series or parallel to increase power output.
6. Upgrade your charge controller: If you’re using a PWM charge controller, consider switching to an MPPT charge controller. Depending on your location, this may have a smaller or larger effect on energy production.
7. Upgrade your panels: If you have older or low-efficiency solar panels, swap them for newer or higher-efficiency panels.

Of course, as a last resort, you can always just buy a bigger solar panel.

Tip: If you try the above and your solar panel is still producing significantly less energy than you expect, your panel may be damaged. At that point, I’d recommend testing your solar panel.

The Bottom Line

After 10 days of testing, I learned that, on average, a 100 watt solar panel will output around 300-500 watt hours per day. However, solar panel output can vary widely based on factors like shading, weather, location, and time of year.

For instance, the lowest output I measured in a day was 50 watt hours, while the highest I measured in a day was 590 watt hours.

If you want to increase your solar panel’s power output, the easiest ways to do this are by moving the solar panel to a sunnier location, reducing shading by trimming branches or moving objects that cast shade on the panel, optimizing the panel’s tilt and azimuth angle, and cleaning the solar panel when it gets dirty.

If those methods fail, you can increase output by buying another panel and wiring them in series or parallel. And, as a last resort, you can always buy a bigger solar panel.