How many solar panels do I need for 1200 kWh per month?

When looking to install solar panels for your home, one of the first questions to answer is how many solar panels you will need. The number of solar panels needed depends on several factors – most importantly, how much electricity you use per month. For a typical home using around 1200 kWh per month, you will likely need 20-28 standard sized solar panels to offset your entire electricity usage.

How much electricity does the average home use?

As a baseline, the average U.S. home uses around 900 kWh per month. However, electricity usage can vary greatly depending on the size of your home, number of residents, appliances, climate where you live, and efficiency. Larger homes or those with electric heating and cooling systems may use 1500-3000 kWh per month. More energy efficient homes may use as little as 500-800 kWh. Checking your monthly utility bills will show your actual average electricity usage.

How much electricity can one solar panel produce?

The amount of electricity generated by a single solar panel (also known as its output) is measured in watts. Standard residential solar panels today have power ratings ranging from 250 to 400 watts, with an average of around 320 watts per panel.

To estimate how much energy a solar panel will generate per month, you need to consider the panel’s wattage rating, sunlight hours available in your area, and panel efficiency losses. As a general rule of thumb for most U.S. climates, you can expect around 30 kWh per month per 250 watts of solar panel power capacity. So on average, a standard 320 watt solar panel can generate approximately 96 kWh of electricity per month under ideal sunlight conditions.

How many solar panels for 1200 kWh per month?

By dividing your needed monthly energy production by the estimated output per panel, you can calculate how many solar panels are needed for your home. In this case, with an average usage of 1200 kWh per month, and standard 320 watt, 96 kWh per month solar panels, you would need approximately:

1200 kWh monthly usage / 96 kWh per panel = 12.5 panels

However, this does not account for inefficiencies in the system. Real world energy losses from temperature, dirt on panels, angling, and equipment can reduce energy production by 20% or more. So it’s best to add an extra 20-30% more panels to reach your target energy output. Factoring in this buffer, you would need closer to 15 to 16 panels for a 1200 kWh per month usage.

Recommendation for 1200 kWh per month usage

For a home needing 1200 kWh of electricity per month, with average sunshine and standard efficiency solar panels, we recommend installing a system with:

  • 20 to 28 x 320 watt solar panels
  • 6-8 kW total solar array size

This properly oversizes the system to account for real-world efficiency losses and ensures you can produce sufficient electricity to offset 100% of your usage throughout the year.

Factors that influence solar panel system size

When designing your solar system, there are a few key factors that will determine exactly how many solar panels you need:

Location and average sunlight

The hours and intensity of sunlight in your area impacts how much energy your panels can produce. Sunnier locations will require fewer panels than shadier ones for the same energy usage. Check your regional climate data for monthly sunlight hours.

Roof space and layout

Your available unshaded roof space will ultimately limit the number of panels you can install. Layout and spacing requirements also impact capacity. Consider if you will need to split the system across multiple roof sections.

Efficiency of solar panels

Higher efficiency solar panels (with power ratings of 360W or more) will require fewer panels than standard models. But they are typically more expensive. Calculate costs vs. benefits when choosing panels.

Home energy efficiency

Reducing your home’s overall energy usage through efficiency measures will also decrease the solar system size required. Do an energy audit first before installing solar panels.

Future energy needs

It’s recommended to oversize your solar array by 20-30% above your current usage to account for future energy increases from an EV, appliance upgrades, etc. This prevents having to expand the system later.

Battery storage

Adding solar batteries will increase the number of panels needed to charge the battery capacity for overnight use. Factor in your storage needs.

Estimating your system size

The table below provides an quick reference for the approximate number of solar panels (320 watt rating) needed based on your monthly energy requirements:

Monthly Energy Usage Panels Needed
500 kWh 5-7 panels
800 kWh 8-10 panels
1100 kWh 12-14 panels
1500 kWh 16-20 panels
1800 kWh 20-24 panels
2100 kWh 24-28 panels
2400 kWh 28-32 panels

These are estimates only – your actual needs will depend on the specific factors mentioned above. Consult a qualified solar installer to model your home’s energy usage and design an appropriately sized solar system.

Cost of solar panels

For a typical 5 kW solar system size suitable for 1200 kWh per month usage, you can expect to pay $9,000 to $15,000 for panel equipment and installation before any solar incentives or tax credits. Larger solar arrays will fall at the higher end of this price range. Key factors impacting solar panel system costs include:

  • Type of panels (standard, premium, high efficiency)
  • Number of panels needed
  • Power output size of the overall system
  • Roof type and complexity – tile vs. shingle, pitch, number of levels
  • Add-ons like solar battery storage, wifi monitoring, etc.
  • Local labor and permitting costs

To get an accurate total price quote for purchasing and installing the number of solar panels needed for your specific home, always consult with multiple solar companies in your region to compare. Many homeowners can reduce out-of-pocket solar costs by taking advantage of federal and local solar incentives, utility rebates, solar tax credits, and low-interest solar loans.

DIY solar panel installation

While solar panel installation is possible as a DIY project, we strongly advise against homeowners attempting it themselves unless they have extensive electrical and construction experience. Mistakes in solar wiring and connections can cause fires or electrocution if not properly handled. And faulty roof penetrations can lead to dangerous leaks and water damage.

For a safe, code-compliant, and high performance solar array, it’s highly recommended to have your solar panels installed by NABCEP-certified solar professionals. Reputable solar companies have the experience, training, and liability coverage to properly assess your home, design a system to meet your energy needs, obtain permits, and install the equipment to manufacturer specifications.

Trying to save money by installing solar panels yourself not only puts your home at risk, but could void warranties from panel manufacturers if procedures are not followed. You also won’t be able to take advantage of solar tax credits and incentives unless your system passes inspection by the local permitting office, which DIY installations may fail.

Solar panel maintenance

Once your solar panel system is professionally installed, minimal maintenance is required to keep it running efficiently for decades. Basic solar panel maintenance includes:

  • Checking that panels are clear of debris, snow, leaves, bird droppings etc. and cleaning panels as needed. This is typically done 1-4 times per year.
  • Trim any trees that may be overhanging and shading the solar array.
  • Check cable connections to make sure they are secure.
  • Confirm solar inverter is operating properly.
  • Monitor production output compared to expected amounts.
  • Have a solar company perform a more thorough inspection every 3-5 years to check for damage, loose parts, corrosion etc. Most issues can be repaired or replaced if caught early.

It’s a good idea to wash solar panels whenever output appears lower than normal as dirt build-up can reduce energy production. But otherwise, modern solar panels are very low maintenance once installed correctly. Monitoring your solar system production data regularly (either through an app or your utility) allows you to quickly detect any potential problems.

Are solar panels worth it?

Installing solar panels on your home is a major investment, and determining if solar is ultimately worth the cost depends on many variables. For most homeowners needing at least 500 kWh of energy per month, solar can provide very good long-term value through:

  • Lower monthly electric bills by 40-100%
  • Zeroing out high cost tiered or peak pricing from utilities
  • 30% federal solar tax credit and additional state/local incentives
  • Added home resale value compared to non-solar homes
  • Hedge against rising energy costs over the system’s 25+ year lifespan
  • Lower lifetime carbon footprint

Figuring your specific return on investment timeline and calculating the years to break even on your solar panel cost depends on state and local electricity costs, the size of system you need, and available incentives. For many homeowners, the payback period now ranges from 5-10 years for a professionally installed solar system. Maintenance costs are also very low over this timeframe. This makes solar energy a smart long-term investment for most homes with adequate sun exposure and roof space.


Installing solar panels is a big commitment that requires carefully planning out the system size and equipment needed for your unique home energy requirements. For a typical single family home using around 1200 kWh per month, you will need a solar array with 20-28 panels rated around 320 watts to offset your entire electricity usage. The total cost will be around $9,000-$15,000 depending on your specific location, roof type, and components chosen. While not inexpensive upfront, solar panels can provide decades of free renewable energy and financial savings in the long run. If you have the appropriate roof space and sun exposure, solar energy is a smart way to take control of your electricity costs while also going green.

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