What Size Solar Power System?

Follow these procedures to calculate your home’s average electricity consumption and PV needs before you start sizing a solar system:

Calculate Your kWh Usage

  • Take a look at your electric bill to see how many kilowatt-hours (kWh) you used. To look at peaks and valleys in usage across a year, you’ll need a complete year’s worth of data. The use of your A/C and heating systems increases your energy consumption in the summer and winter.
  • Calculate your average monthly kWh consumption. To calculate your average monthly use, add up your kWh usage over the last 12 months and divide by 12. In the summer, when the sun is at its strongest, your grid-tied system will likely to overproduce.

Use our home appliances power consumption table to find out how many kWh your appliances would use per month to better evaluate your home’s energy usage.

The energy your system creates can be banked with your utility as a credit that can be used later if your utility has a favorable net metering policy. Check with your local utility company to see if they will give you credit.

Look Up Your Peak Sun Hours

The average peak solar hours vary a lot depending on where you live and how hot it is. To get the most of solar electricity, you’ll need to figure out how many peak hours of sunlight you’ll get:

  • Look up your peak sun hours on a sun hours chart to see how many hours per day the sun produces the most sunshine.
  • Write down the daily average of peak solar hours in the city closest to you.

Calculate the Size of Your Solar System

To determine the size of your solar system, multiply your daily kWh energy need by your peak sun hours to get the kW output. Then divide the kW output by the efficiency of your solar panels to get an estimate of how many solar panels you’ll need for your system.

How big should a solar system be?

We can estimate a general system size for you based on your annual electricity and monthly use patterns. To do so, we utilize a rule-of-thumb value for solar production in North Carolina to estimate the size of the system you’ll require. Our rule of thumb is that 1 kilowatt (kW) of solar installed in North Carolina will provide 1,300 kilowatt hours (kWh) per year, based on our experience. So, if your home consumes 12,000 kWh per year, a 9.2 kW solar system would be required to supply 100 percent of your energy needs (12,000/1,300 = 9.2).

What is the typical solar system size for a home?

The three inputs above can be used to calculate how many solar panels you need, but there are many more aspects to consider when choosing the size of your ideal solar panel system. When it comes to planning your optimal solar panel setup, it’s crucial to understand production ratios, the relationship between system size and number of panels, and the impact of home size.

How many kWh can your solar panels produce?

The quantity of power (kWh) that your solar energy system can generate is determined by the amount of sunshine that your roof receives, which determines your production ratio. The amount of sunlight you receive in a year is determined by both your location in the country and the time of year. California, for example, has more sunny days per year than New England. However, regardless of where you live, you’ll be able to generate enough energy to meet your demands and eliminate your utility billsif you live in an area with fewer peak sunlight hours, you’ll simply need a larger solar array system placed at your home. As a result, production ratios vary by location, and a lower production ratio (due to less sunlight) implies you’ll need more solar panels to produce the amount of energy you require.

Here’s an example: two similarly sized families in California and Massachusetts use the same amount of power as an average American household, which is 10,715 kWh per year. To meet 100 percent of their energy consumption, a California family would require a 6.8 kW system. In Massachusetts, a comparable home would require an 8.2 kW system to meet their energy needs. Solar panel systems in California are smaller than those in Massachusetts, yet they produce the same amount of energy since they receive more peak sunlight hours each year. Homeowners in less sunny places, such as Massachusetts, can compensate by utilizing more efficient panels or expanding the size of their solar energy system, resulting in somewhat more solar panels on their roof.

How many solar panels do you need for specific system sizes?

We estimated that a 6.8 kW system would probably cover the average energy use for an American household if you reside in a region with a production ratio of 1.6, which would be a reasonable value for homes in most parts of California, in our extended example at the beginning of this essay.

Number of solar panels needed for specific system sizes

The table above assumes you’re using a 340 solar panel once more; however, the number of panels you’ll need to power your home and the amount of space your system will take up on your roof will differ depending on whether you’re using lower-efficiency panels or high-efficiency panels (which generally correlates to low and high power rating, respectively). Based on the electricity output of the solar panels you choose, the table below will show you how much space your system will take up on your roof:

Square footage of different size solar panel systems

Estimating your household’s annual energy demand is perhaps one of the most difficult components of sizing a solar panel installation. A variety of larger consumer products or add-ons might drastically alter your annual kWh requirements and, as a result, the quantity of panels you’ll need. If you have central air conditioning or a heated swimming pool in your backyard, the size of your solar panel array may need to be adjusted significantly. You should examine the energy effect of various things you own or are considering for your home to obtain a sense of the size you’ll require.

The size of solar panels is particularly crucial to consider if your property is small or has a uniquely shaped roof. While homeowners with a wide roof may be able to sacrifice some efficiency and purchase larger panels to obtain the ideal energy output, individuals with a smaller roof must be able to utilize fewer small high-efficiency panels such as those from SunPower, LG, or REC to achieve the best results. For such unusual roofs, you can wind up with something like this:

Solar panels for a residential home nowadays are typically 65 inches by 39 inches, or 5.4 feet by 3.25 feet.

How does my home size affect the amount of solar panels I need?

While the size of solar panels has remained relatively constant throughout the years, the power production from the same area has improved substantially. SunPower, for example, has reduced the size of gaps between panels and uses invisible frame and mounting hardware to make the panels compact, efficient, and aesthetically beautiful. Based on your home’s square footage, use the table below to get a rough idea of how many solar panels you’ll need.

How many solar panels do I need for common appliances?

When you look at the various kWh requirements for common household appliances and products, one thing becomes clear: certain add-ons may drastically alter your monthly energy use, and can have a significant impact on the size of the solar panel system you should install. Combining an electric vehicle with solar panels, for example, is a terrific method to cut carbon emissions and improve energy efficiency; but, it should be planned carefully, since it may quadruple the size of your PV system.

Though it is feasible to construct a solar system and then have extra panels added later to meet rising energy needs, the most practical alternative is to size your system as exactly as possible based on your anticipated purchasessuch as an electric vehicle, swimming pool, or central air system. Any new solar homeowner should make it a practice to ask themselves, “How many solar panels will I need for my refrigerator, hot tub, and other appliances?”

For a residence of 2000 square feet, how many solar panels do I need?

People frequently inquire about the number of solar panels they will require dependent on the size of their property. However, for solar electric system design, the amount of electricity you use is more significant than the size of your home. This is primarily due to the wide range of ways in which people consume power.

Let’s imagine two family dwell in 2,000 square foot houses next door to each other. A young man and his fiance live in Home A; they both work long hours and frequently socialize with friends in the evenings. As a result, they use very little electricity and only pay around $40 each month.

Two parents and their two teenage children live in Home B. They are either using power to filter their pool or operating the heater or air conditioner, while the teenagers are always on their iPads, opening the refrigerator, or watching TV. Because there are more people living in the residence and their lifestyle necessitates more energy, their monthly electricity expenses are around $325.

Despite the fact that they live in identical homes, the family in Home B would most likely need to invest in more solar panels to reduce their electricity consumption than the couple in Home A.

Even if the residences consumed the same amount of electricity, one may have better solar exposure or less shade than the other, resulting in more or less panels.

The quantity of energy you use now is also significant because most utility companies in Los Angeles and Orange County limit the size of your solar system based on how much energy you use now. This figure is usually calculated by looking at how much electricity you used in the previous year.

There are, of course, certain exceptions to the rule. If you’ve just been in your home for a few months or want to put solar panels on a property that’s still being built, most utility companies will let us estimate your usage based on the square footage of your home.

The Los Angeles Department of Water and Power, for example, calculates this type of average as 2 watts per square foot. A 4,000-watt solar array would be authorized for a 2,000-square-foot residence. A system of this size could range from 12 to 18 solar panels, depending on the type of panel you choose. Keep in mind that the formula for estimating usage differs based on your electrical provider.

Another exception is sometimes allowed for persons who anticipate an increase in their electricity consumption. We can estimate the additional demand and put it into the solar panel design and cost if you plan to buy an EV (electric car) or install central air, for example. The utilities, on the other hand, are finicky! They’ll require proof of purchase in addition to the solar system application.

How much kWh of solar power do I require?

So, how many solar panels do you need to power a home based on these factors? You’ll need to figure out two things to estimate how many solar panels you’ll need without a professional assessment: how much energy you use and how much electricity your panels will produce.

Calculating How Many Kilowatt-Hours Your Home Uses

The average American home uses 10,649 kWh of energy per year, according to the latest figures from the US Energy Information Administration (EIA). This, however, differs from state to state. Consider the following scenario:

Add up the kWh indicated on your last 12 power bills to get a better idea of how much energy you consume annually. The size of your home, the number of occupants, your electricity usage patterns, and the energy efficiency rating of your home gadgets will all influence these figures.

Solar Panel Specific Yield

After you’ve calculated how many kWh your home needs annually, you’ll need to calculate how many kWh each of your solar panels produces over the course of a year. This will vary depending on the type of solar panel used, the roof’s characteristics, and the location’s peak sunlight hours.

In the solar power industry, a common metric used to estimate system capacity is “specific yield or “specific production. This is the annual kWh of energy produced for each kilowatt of installed solar capacity. The amount of sunshine accessible in your location has a big impact on your yield.

Check credible sources like the World Bank solar maps or the National Renewable Energy Laboratory’s solar radiation database to obtain a better sense of the specific yield that can be attained in your location. Divide your annual kWh usage by the specific yield per kilowatt of solar capacity to find how many kW are required to power a home.

For example, if your home uses 15,000 kWh of energy per year and solar panels in your area produce 1,500 kWh/kWp, you’ll need a system with a capacity of roughly 10 kilowatts. Paradise Energy Solutions has also devised a general formula for estimating the size of solar panel system you’ll require.

Simply multiply your annual kWh by 1,200 to get the required solar capacity in kilowatts. So, if your total energy consumption during the last 12 months is 24,000 kWh, you’ll require a 20 kW system (24,000 / 1,200 = 20).

Should I go for a larger solar system?

A reasonable rule of thumb when constructing your system is that your solar panels should be 10-20% larger than your inverter. Due to higher efficiency losses from heat in warmer climes, this can be extended up to 30%.

We commonly couple the 290W Enphase IQ7+ micro-inverter with a solar panel in the 320W-350W range for micro-inverters.

The SolarEdge HDWave 7.6kW string inverter can be used with a solar array ranging from 8360W to 9120W. On a 7,600-watt inverter, for example, you might utilize three strings of 335W panels, each with nine panels, for a total of 9,045 watts.

In both situations, the manufacturers offer a considerably wider range of panelsEnphase recommends 235W-440W panels for the IQ7+, while SolarEdge specifies a maximum of 11,800 watts for their 7.6kW HD-Wave. These parameters specify what the inverters can safely handle, however we propose the tighter ranges above to assist users get the most out of their system for the money they spend. Keep in mind that this will vary based on your environment and other production-related factors.

To get off the grid, how big of a solar system do I need?

As you shop, you’ll see that panels and inverters are often available in 12, 24, or 48 volt configurations. Because most RVs and boats have 12V battery banks, 12V panels are commonly used. Many bigger household systems are now rated at 24v or 48v, whereas 12 volt systems were once the norm.

RVs/motorhomes/vans, camper trailers, and small cottages or tiny homes are all suitable candidates for 12v solar systems. Choose a 24 volt system if your energy needs are between 1,000 and 5,000 watts. If you need more than 3,000 watts of power, a 48 volt system is the way to go. 48 volt systems are commonly used in large off-grid homes.

What is the output of a 15kW solar system?

SunWatts offers a large selection of low-cost 15 kW PV systems. Solar panels, DC-to-AC inverter, rack mounting system, hardware, cabling, permit plans, and instructions are included in these 15 kW grid-connected solar kits. These are comprehensive PV solar power systems that can be used for either a home or a business, and include almost everything you’ll need to get the system up and operating quickly. The prices listed are simply for the hardware components; click on any kit to add full-service installation for rooftop or ground mount.

A 15kW Solar Kit will take up to 1,200 square feet. 15kW, or 15 kilowatts, is a DC direct current power output of 15,000 watts. With at least 5 sun hours per day and the solar array oriented south, this might create 1,000 to 2,500 kilowatt hours (kWh) of alternating current (AC) power each month. For greatest solar power, an unobstructed south-facing view of the sun will yield the highest production. The amount of power generated depends on the location, equipment, and installation. Compare how much power these low-cost 15kW PV systems can generate to the actual kWh used each month on your electric utility bill.

For 1000 kWh per month, how many solar panels do I need?

A solar panel system that produces 1,000 kWh per month is required. 24.69 solar panels = 1000 kWh / 40.5 kWh Whew! We arrived at our conclusion after a lot of arithmetic.

Why are solar panels a waste of money?

Because solar panels cannot store electricity, their production will be reduced in overcast conditions and will be nil at night. As a result, most home solar systems necessitate the usage of a solar battery. When evaluating if solar panels are worth it for you, keep this additional expense in mind.