How Much Power Does a 400W Solar Panel Produce?

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A lot of homes use 400W solar arrays with great results. But it can be just as effective on RVs, vans and campers. A single 400w panel produces plenty of power that RVers will appreciate, and it is easy to set up.

One 400w solar panel produces around 564kwh per year, 47kwh / month, 1.5kwh / day. 1.5 kwh is about 1500-1750 watts a day with 5 hours of sunlight. More sunlight and higher output efficiency leads to higher energy draws.

How to Calculate 400W Solar Panel Power Output

We arrived at the 1500-1750W figure by assuming the solar panel output is 320-360W with 5 hours of sunlight. The sun angle, panel efficiency, clouds, shading affect the amount of energy received. 320-360W is the typical output on a clear day. In exceptional conditions (summer, clear sky, lots of sun) the output could reach 400W.

Even if the panel reaches 400W it is unlikely to remain at that level. More likely it will fluctuate from 330-400W on a clear day, averaging to 360W. You can always adjust the value if your solar panel produces more or less. After 5 hours under the sun you will have a good idea of the watt hours. Multiply watt hours by number of sunlight hours and you have the daily output.

Do You Need 400W Solar Panels?

A 400w solar panel is ideal if you fall under any of the following categories.

Lives or Spends a Lot of time in an RV: living in an RV full time requires more than a typical 250W system. If you spend several weeks a year boondocking a 400W system can provide the extra power you need.

Have a large RV: a big RV means more space for appliances and devices. That also means more solar power is required. Rather than install multiple solar panels on your roof, you can try one 400W solar panel (maybe even two) and have all the power you need.

Need a lot of solar power: do you carry and use multiple gadgets? Do you microwave or use a coffee machine? These devices consume a lot of power and and a small solar panel will not last.

An array of 400W solar panels is ideal in homes too. It is easier to install a few 400W than dozens of 100-250W solar panels. The fewer panels to install the cheaper the installation and the cleaning service will be. Just like with RVs, you should calculate how much power you need. Once you have the number you can buy the required array.

What Can You Do With 400 Watts?

The following are some common appliances and devices you can use with a single 400W solar panel. Keep in mind that appliances have different energy consumptions, so check the product manual for specific details.

  • DVD players
  • Video game consoles
  • 32 inch TV
  • LED lights
  • Music players
  • Cameras
  • Smartphones
  • Laptop
  • Desktop computer
  • Tablet
  • Blender

Obviously your solar panel cannot run all these at the same time. But it is unlikely you will. Blenders are energy hogs but you only use it a few minutes a day. Same with coffee makers and other kitchen appliances. You probably won’t use the TV, laptop and video game console at the same either.

The bottom line is 400W is a lot especially for RV owners, who are always looking for ways to save energy. Combine this with a battery and you do not even have to run these on solar panel. You charge the battery and use that to run the appliances.

Your appliance list may be different from this. You just have to list down what devices you will use, total their watts and see if it fits under 350W-400W. Even easier is to just check your monthly bill and you will know if the solar panel is enough.

400W Solar Panel For RV Accessories List

Besides the solar panel you will need some components to get the highest possible output. If you bought a 400W solar panel kit most of the stuff you need are included. if this is what you want, we suggest the Renogy 400W Starter Kit as it comes with the essentials.

We recommend the following for a 400W solar panel system. This is for RVs, campers and vans. For homes, determine how many 400W solar panels you will need. If you are grid tied a solar battery is not necessary. If you are off the grid it is mandatory. And you will need a lot more than what is listed here.

400W Solar Panel Kit

A solar panel kit is ideal because it comes with all the connectors you will need.. Kits come with different components so you should look for the following.

400W monocrystalline panel: it can be 1 x 400, 2 x 200 or 1 x long as it is monocrystalline.
MPPT controller fuse: some kits include a charge controller. If not it should at least have an MPPT fuse.
Brackets; 4x Z brackets is enough to install solar panels on an RV.
Extension cable: check your setup to determine how long the cable should be. Inline fuses and MC4 connectors are a must.

1000-1200W Inverter

Inverters come in various sizes, but for most RV owners, 1200W is enough. Always err on the side of caution especially if you use consume a lot of power. The rule of thumb is to double the total watt usage and have a safety margin. For 400W you need an 800W inverter minimum.

We recommend going with 1000-1200W in case of emergency requirements. Some appliances have high surge watt usage so you have to account for that. If you have plans of using more solar power in the future, get a large inverter now.

There are two inverter options, pure sine wave or modified sine waver. Pure sine wave inverters are compatible with all AC appliances and have greater efficiency. Modified sine wave inverters work with 95% of AC electronics. They are more affordable but generate energy losses up to 25%. They also produce a hum when running.

200ah Lithium ion or 300ah Lead Acid Battery

Lead acid batteries have a 50% DOD so you can only use 150ah here. If you use 300ah every day, get a 600ah battery. Either way, there is enough power to charge your solar panel and run various devices at night. Of course you should get a higher capacity if necessary.

A 400W solar panel can produce 1500W a day. If you cannot use it all up the rest is stored in the battery. This way you can run electronics at night and recharge the battery in the morning. The reserve power will be put to use during the winter and overcast days. Note the solar panel and battery have to be the right distance for the best results.

For lead acid batteries, get 2 or 4 with a 100ah capacity each. The life cycle should be 150-300. For lithium ion, 3000-5000 life cycle is ideal. The depth of discharge can be 30% or even 1000%. If you want more power you can use a 400ah battery.

40A MPPT Charge Controller

For high powered solar panels an MPPT controller is better than a PWM. 40A can handle 400W and the controller ensures optimum energy transmission without damaging the battery or solar panel. Setting one up is easy, just make sure the controller is no more than 1 meter from the battery. Keep this in mind if you are computing the amps.

Keep Other 400W Solar Panel Components

You will need a copper wire to connect DC appliances, a battery to battery cable and an MC4 branch connector. Also get a battery monitor, solar panel mounts, charge controller circuit breaker (make sure it is for a 40A MPPT ) and a battery to inverter fuse. Most of these will probably be included when you buy the inverter or solar panel kit.


During the early days of solar technology, 400W solar panels were rare and expensive. Nowadays it is a necessity for many RV owners and homes. With this power you can be confident of running all your devices without fear of suddenly running out of power.