How Many Solar Panels Do I Need For 1000 kWh Per Month?

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A common goal in residential green energy is to develop a solar panel system that can provide 1000 kWh of power per month, and it’s not just because 1K is a nice, big round number.

How Many Solar Panels Do I Need For 1000 kWh Per Month

The average American household consumes roughly 900 kWh per month, so establishing a 1K kWh solar system covers the entirety of that usage, with the excess accounting for power losses and overcast days.

Yep, the 1K solar energy threshold is based on pretty airtight logic, but it may leave you wondering how many solar panels you’d need to achieve such a robust energy yield. So, let’s look into the matter in more detail, shall we?

How Many Solar Panels Does It Take To Generate 1000 kWh Per Month?

Now, I know you were probably looking for a quick answer when you looked out this article, and I will try to keep things lean here, but there isn’t really a one-size-fits-all answer for the following reasons:

  • Solar panels are not made equal.

Panels can be rated for different outputs, and some will be kitted out with more efficient technologies than others. As such, the size of a 1K kWh array will differ from panel to panel.

  • Certain properties and places are more suitable than others for solar panels. 

Houses that fall into the average 900 kWh per month zone may need to super-size their solar array if their house or general location doesn’t lend itself all that well to solar augmentation.

For example, properties without south-facing roofs or those shrouded in the shade of a larger neighboring building or tree won’t be able to pull in 1K kWh per month, even with a system that is technically capable of such a feat.

Another example would be houses in cities and states that don’t get a lot of sun. Generally speaking, more cloud cover means you’ll need a few more panels to keep up with the demands of your lifestyle.

… Don’t worry, though, friend, as I’m going to tell you how you’d figure out exactly how many solar panels you’d need to suit your situation.

How To Calculate How Much Solar Energy You Will Need Per Month To Run Your Household

To calculate the number of solar panels you’d need to produce 1000 kWh per month, you first need to figure out:

  1. Your home energy consumption is kWh per day.
  2. The irradiance value (kW/m2/day) of your location. In other words, how much sun do you expect to receive per day?
  3. The wattage of one of the panels you intend to purchase.
  4. How many solar panels you’d need to produce 1 kWh per day?

Then, simply multiply the number of panels required to produce 1 kWh per day, by the kWh you consume in a day, and voilà; that’s the baseline number of panels you’d need to hit 1000 kWh per month, in ideal conditions, that is.

Let’s take a hypothetical home to illustrate how these calculations work in practice. Here are the details of our imaginary homestead:

  • Energy used per month: 1000 kWh, per week: 250 kWh, per day: 36 kWh (rounded up)
  • Irradiance value: 4 kWh/m2/day (average across the US), meaning solar panels would be exposed to four hours of bright sun per day.
  • Individual panel output: 250 watts

A single 250-watt solar panel would require 4 hours of sunlight to produce 1 kWh of energy, as 4 x 250 watts = 1000 watts. That means that 1 panel = 1 kWh per day, but we need to produce 36 per day to meet our monthly energy demands, meaning we need 36 panels in total.

However, it’s important to bear in mind that solar panels rarely perform as well as they’re advertised to, so if you truly want to bring in 1000 kWh of solar energy, consider the following:

  • Account for energy loss an inevitability of solar power. A good rule of thumb is to boost your system by between 20–25%. So, if you’re looking to pull in 1000 kWh, you should be aiming for a system rated for 1200–1250 kWh.
  • To finish things up, simply add another 10% to the size of the array to account for gloomy weather.

So, let’s say we wanted to compensate for power loss and bad weather by adding a full 35% buffer, we’d need another 13 solar panels in our hypothetical array to truly yield 1000 kWh per month. That brings our panel total to 49.

How To Calculate kWh Energy Usage Per Day

Unfortunately, it can be quite arduous figuring out how many kWh you use per day, as the energy bill only informs you of the amount you owe, rather than what the money equates to in watts or kilowatts.

Unless you have something like the amazing Sense Energy Monitor that tracks your power usage for you, you’re stuck doing things the old-fashioned way:

  • Multiplying the wattage of every appliance you use throughout the day by the hours you use them for.
  • Add the totals together.
  • Divide the sum total by 1000 to convert watts into kilowatts.

Of course, if you know for a fact that you’re using 1000 kWh per month, things are a lot easier. All you’d need to do is divide 1000 by 4 to find your weekly kWh use, then divide that by 7 to find your daily kWh use.

How To Calculate Irradiance Value Of A Location

Unless you’re an actual scientist, calculating solar irradiance can be tricky, which is why I praise Ra for the existence of the Fluke IRR1 Solar Irradiance Meter.

Simply set this little gadget down in the spot where you want your solar panels to sit, wait for a moment, and it will provide a reading of the solar irradiance in the area — perfect!

Final Thoughts

In summation, the number of solar panels you’d need to pull 1000 kWh per month depends on the suitability of your property for solar system installation, and where the property is located.

As long as you factor those variables into your calculations, you’ll be able to drum up a super accurate estimation of the number of solar panels required to cover your monthly energy consumption.