A typical American home needs around 28 to 34 solar panels to cover its energy consumption. If you need a close estimate for your home, though, you need to consider many factors.
You’ll need to learn your household’s energy consumption and your property’s peak sunlight hours. Other factors like the orientation of your roof and the solar panels’ wattage may also come into play.
It may seem overwhelming, but don’t worry; we’ll walk you through it with our energy guide. Keep on reading to know how to estimate how many solar panels you’ll need.
Know Your Energy Consumption
The best and easiest way to know how much power your household needs is to look at your bills. You need the number of kilowatt-hours your household uses in a year.
Some companies provide your total consumption in your bill. Otherwise, gather your 12 most recent monthly bills and add them up.
The bills have to be from January to December as your usage also depends on the weather. You’re more likely to use more electricity during the winter months, for example, for heating.
For reference, the average household uses around 10,649 kWh in a year. It can be lower or higher depending on your home’s size and location. In Louisiana, the average annual consumption of a residential customer is 14,787 kWh.
One kWh is 1,000 watts per hour. That’s the same as running ten 100-watt light bulbs for one hour.
Make sure to consider any house extension or major appliances you plan to buy soon. Adding a heated pool, for example, will add a huge chunk to your consumption. An electric vehicle would add around 3,000 kWh.
Remember that your consumption rate isn’t always what you’ll need from your solar energy system. For instance, some homeowners only aim to produce a percentage of their usage. This already gives them huge savings on top of the benefits of using renewable energy.
You can always choose to cover your whole consumption if you want sustainable living. However, note that you’ll need a bigger system the bigger your needs are.
How Much Energy Do Solar Panels Produce?
To gauge how many solar panels you’ll need, note that most residential units produce 250 to 400 watts per hour. However, many factors affect the actual production rate of these panels.
1. Peak Sunlight Hours
Solar panels won’t work in the shade or even in indirect light. They can only produce energy under direct sunlight, which we refer to as peak sunlight hours. To be specific, a peak sun-hour is an hour wherein the intensity of sunlight is at 1,000 watts per square meter.
This will depend on your location. For example, those in California enjoy more sun than in some states. As such, their solar panels have higher production.
Even though there are around 7 hours of daylight, the average peak sunlight hours are only at 3 to 4. The weather can affect this, so don’t expect the same production rate each day or month.
Another factor that can affect this is your environment. Is there a building nearby that limits your sunlight hours? Is there a tree on your property that provides shade on most of your roof?
Either way, you’ll get less out of your solar panels even if you’re in a sunny state. You’ll need more panels to hit your target energy production.
2. Solar Panel Production
Knowing the average production ratio in your state gives you a better idea of how many panels you need. In the Midwest, for instance, a solar panel system has a production ratio range of 1.1 to 1.3. On the West Coast, it’s higher at 1.4 to 1.8.
To estimate how many panels you’ll need for full coverage, you need to get your annual consumption in kWh. Combine this with the wattage of the solar panels you’re planning to use.
You then divide your annual consumption by the production ratio. Then, you divide the result by the wattage.
Let’s say you use 10,000 kWh per year, and you want to use 250-watt solar panels in the Midwest. The computation will look like this:
10,000 / 1.1 = 9,090 / 250 = 36.36.
Using this computation alone, you’ll need 37 solar panels to cover your whole consumption. Still, it can be hard for a homeowner to do a self-assessment. You’ll have to get a professional, like Blue Raven Solar, to get a more accurate assessment.
3. Roof Size and Orientation
The best orientation for roofs is true south. This allows roof-mounted solar panels to receive as much light as possible. East and west-facing roofs will work, but north-facing roofs aren’t ideal for energy production.
The size of your roof also matters. Your roof might not be able to fit 37 solar panels in a good area, for example. In general, 5-kW solar panels need around 250 square feet of space.
There’s the issue of whether your roof is suitable for solar panels. They’re a long-term commitment, so you first need to make sure your roof is up to the task.
Supplementing the Energy from the Grid
Your solar panels won’t be able to produce a consistent amount of energy all-year-round. The amount of sunlight is the primary factor. So, what happens if you have a low production?
With a grid-tied system, you can still draw power from your electric utility if your solar energy system can’t produce enough for your needs. You’ll only have to pay for what you use.
In case you produce more than you need, you might be able to sell it to the utility if they have a net metering policy. That means they’ll give you credits to use some other time towards your bills.
How to Get an Accurate Energy Guide
With our energy guide, you can estimate how much you’ll need for your home. However, it’s still better to get a professional for a more accurate assessment.
Solar companies will assess your location, the condition of your roof and give you an idea of how many solar panels you’ll need. Solar panels are a great first step towards more sustainable living, but you don’t have to stop here! Check out our other blog posts for more guides on how to live sustainably.