How much does it cost to install 400 watt solar panels?

National Average Range:
$5,000 - $9,000

Get free estimates from solar energy contractors near you

Get local cost

Updated: August 18, 2022

Reviewed by Cristina Miguelez remodeling expert. Written by

To provide you with the most accurate and up-to-date cost figures, we gather information from a variety of pricing databases, licensed contractors, and industry experts.

Most people who install solar panels need a total of 3,000 to 5,000 kW, and those who want to go off-grid need even more. For this reason, many people choose to install 400-watt solar panels. While panels come in watts as low as 250, 400-watt panels can mean you need fewer of them. This is beneficial for those with smaller roofs or less space in a sunny area. 400-watt solar panels come in many types, from polycrystalline to thin film. This means these panels may have a wide range of associated costs.

The national average cost range for installing 400-watt solar panels is $5,000 to $9,000, with most people spending around $7,000 for 10 mono-si 400-watt panels fully installed. This project’s low cost is $4,000 to install 10 cadmium telluride thin-film panels. The high cost is $10,000 for 10 PERC monocrystalline 400-watt panels installed.

400-Watt Solar Panel Cost Calculator

400-watt solar panels can be found in nearly all types, including thin film, polycrystalline, and monocrystalline cells. Each type typically has a range of costs based on efficiency, performance, and production difficulty. Of these, some types of thin-film and polycrystalline panels are the lowest cost, while other thin film and polycrystalline panels, along with mono-si monocrystalline panels, have moderate costs. The highest quality is generally reserved for PERC monocrystalline cells. Below are the average costs for 10 400-watt solar panels of varying qualities.

400 watts is the upper end of what many panels can hold. While you can find panels with more, these are typically bifacial, with cells on both sides of the panel. This makes 400-watt panels more costly than others. However, you often need fewer panels to run your system because each panel has more watts, resulting in space-saving and lower maintenance.

What Will a 400-Watt Solar System Run?

If you have a single panel containing 400 watts or a few much smaller panels that add up to 400 watts, this system can run some small appliances. You could simultaneously run a laptop computer, coffee maker, and toaster. You could also run a TV and a ceiling fan or other combination of two to four small appliances. You could also run a small to midsize window air conditioner on this system or a small refrigerator. This system cannot support anything that requires more than 380 watts to run because some wattage is lost to the inverter.

Compare prices from 400-watt solar panel installers near me

Additional Considerations and Costs

  • Top manufacturers. Most manufacturers make 400-watt panels. This includes LG, Tesla, Canadian Solar, and Solaria.
  • Batteries. If you have several panels, you may want to invest in a solar battery. This can store extra energy for when the sun is not as strong. The cost of adding batteries to a 10-panel system ranges from $7,000 to $14,000.
  • Inverters. All solar panels need inverters. This converts solar energy into energy you can use. Inverters add $400 to $3,000 to your project.
  • Accreditation. Make sure that your contractor is accredited with the NABCEP, which offers board certification for installers, to know if the person you hire is qualified.
  • Maintenance. Solar panels are fairly low maintenance. Keep them free of debris and snow, and gently wash them to keep them clean. Have them inspected regularly for the best results.
  • Mounting. Solar panels are commonly mounted on the roof, but they can be mounted on the ground. There are different mounts available for the roof to get the best angle. Some mounts may increase the project cost.


  • How much power does a 400-watt solar panel produce per hour?

A 400-watt solar panel produces between 50 and 125-kilowatt hours each hour. The amount depends on the panel type and the conditions it is installed in.

  • How fast will a 400-watt solar panel charge a 12-volt battery?

It takes between 5 and 8 hours for a 400-watt solar panel to charge a 12-volt battery. The time differs based on the panel type and location.

  • How big is a 400 W solar panel?

The average dimensions of a 400-watt solar panel are 79” X 39” X 1.4”. This varies by brand and panel type, however.