Solar Panels

Best 400 Watt Solar Panel (Reviews & Buying Guide)

By:Michael Johns

400 watt solar panel

If you’re looking for a way to add off-grid power to your life, then a 400 watt solar panel might be for you.

It is a powerful way to generate electricity directly from the sun, even in the most remote locations.

A 400 watt solar panel is one of the largest sizes available on the market which makes them popular with people who rely heavily on solar power.

Whether you want it for your RV, house, cabin, boat, or elsewhere, you’re in the right place.

In this article, you’ll find the most in-depth information along with reviews of the best 400 watt solar panel available today.

So let’s dig in.

How Much Power Does a 400W Solar Panel Generate?

At best a 400 watt solar panel generates 1600Wh of energy based on 4 peak sun hours a day. Remember, you won’t be generating full power during low light conditions in the morning and evening. It would be safe to work on the basis of between 1.2kWh – 1.6kWH of energy a day. That’s around 100Ah – 130Ah a day from a 12V system. This means you will be able to keep a battery storage capacity of 200Ah pretty well charged, depending on how much power you draw.

What can a 400 Watt Solar Panel Run?

A 400 watt solar panel can power many different appliances and devices. When combined with a large leisure battery and 1500 watt power inverter you could easily run electronics like computers, TVs, laptops, slow cookers, phones, lighting, fridges, and other appliances with a wattage rating of fewer than 1200 watts.

Remember, you will only be able to replenish your battery at a maximum rate of 400 watts an hour during the day.

It is important to understand how an off-grid solar panel works to know what you can run. You will be very limited if you try to draw power directly from your solar panel. This is because output will vary based on the sunlight conditions and result in an erratic supply. 

If you are using a solar panel in this way, it is best to use it to charge electronics with a battery such as smartphones, tablets, and digital cameras.

What is a 400 Watt Solar Panel Used For?

Wondering whether a 400W solar panel is right for you? 

There’s a wide range of uses for a system like this including home and commercial buildings, RVs, caravans, camping, van, trucks, boats, and busses. 

They are very adaptable products and brilliant to use anywhere you have enough space and a need for off-grid electricity. 

The only downside is the size of these products, a single solar panel could need as much as 20 square feet of space. This means small vehicles and structures such as golf carts, tents, and sheds might not be big enough!

Best 400 Watt Solar Panel Reviews

1. Giosolar 400 Watts 12 Volts Monocrystalline Solar Panel Kit

Let’s start off this list with a complete starter kit that is perfect to get your solar journey started. This is an ideal kit for virtually any off-grid use including RVs, trucks, golf carts, boats, cabins, and more.

Included in the pack is a set of 400w solar panels, a solar charge controller, cables, and connectors. Basically, it’s ready to hook up with your leisure batteries.

The solar panels consist of four 100 watt units which offer industry-leading performance. The black monocrystalline cells efficiently absorb the sun’s energy and convert it into electricity. Multi-layer sheet lamination improves cell performance while making for a long life span. Super durable aluminum frames hold tempered glass for decades of protection.

A PWN charge controller helps to reduce the cost of the system while offering performance and safety. The controller automatically senses 12v and 24v systems to adjust accordingly. Easily monitor everything using the crisp LCD screen and even charge your phones from the dual USB ports. Rest easy knowing you’re protected against overcharging, reverse polarity, and short circuits.

The all-in-one pack is simple to install on arrival with predrilled holes in the metal frames. Plus the included cables allow you to connect the panels in series and into the charge controller with no worries.

Even a 25-year power output warranty is included for this durable high-performer.


  • Starter kit
  • Includes charge controller
  • Easy to mount
  • Monocrystalline cells
  • High-efficiency
  • Mount of rooftop or vehicle


  • Not portable

2. Renogy 400 Watt 12V Solar Panel Kit for RVs

Another brilliant option if you’re after a 400 watt solar panel kit for RVs.

Renogy’s start kit has everything you need to hook up to your leisure battery plus you can choose between various charge controller options.

The solar panels use the best monocrystalline cells to deliver a conversion efficiency of 21%. On a perfect do you could even generate up to a whopping 2000Wh! That means you could get a decent way to fully charge a 200Ah battery on a long summer’s day.

It’ll last you years too with the anti-corrosion aluminum frames and tempered glass which are impact resistant for your most adventurous journeys.

You can select your preferred charge controller, the Renogy Wanderer comes in 30A PWM or 40A MPPT. This will come down to your budget, as the MPPT option is far more expensive – you will get better performance and battery charging. To be honest, the PWM should be fine for this level of solar power. Be a little careful when selecting your controller, there are choices for positive or negative ground. Plus you will need the MPPT if you want to connect in series rather than parallel.

In terms of installation, you should be able to get everything mounted quickly with predrilled holes and z-mount brackets for a solid fix.

What’s not to like…


  • Monocrystalline cells
  • Durable aluminum and tempered glass
  • Rooftop mountable
  • Great for vehicles
  • Includes charge controller


  • Be careful selecting the right controller

Giosolar 400W Flexible Solar Panel Kit for Boat

Let’s take a look at a system from Giosolar.

This epic kit comes with four flexible solar panels, charge controller, and all the required cables. The panels feature a unique honeycomb design which offers a 10% enhancement of natural light. This enables it to deliver a whopping 23.5% conversion efficiency. That’s more than your traditional products.

With this performance comes incredible flexibility thanks to a 30 degree bend arc. You could happily mount these almost anywhere from a rooftop to curved boat deck. They’re incredibly resilient thanks to the ETFE wrapping which creates a durable weatherproof seal.

The charge controller is the ideal complement with a 12V/24V automatic sensor. Its 40A rating means it will handle your energy requirements without a problem. You can always keep check on everything using the clear digital display. Plus the USB ports are a handy addition for charging phones.

Wherever you need electricity, you can fix this system in place using the steel eyelets and even combine them with glue, velcro, zip ties, and bolts.


  • 23.5% Efficiency 
  • Monocrystalline
  • Flexible
  • Lightweight
  • Very Durable
  • Adaptable


  • Not rigid frame

XINPUGUANG 400W Flexible Solar Panel Kit

If you’re looking for a 400 watt flexible solar panel then check this out.

You’ll be getting efficient performance coupled with an adaptable set of panels. The brilliant thing about flexible panels is the ability to mount them almost anywhere, even on uneven or curved surfaces. This makes them very popular with many vehicle owners, including boats, trucks, trailers, and busses. 

This pack is the complete starter kit too with an included charge controller and cables. The panels offer up to a 30 degree flex arc and each 100w unit weighs just 4lbs, that’s 70% lighter than a traditional panel. Adding to this, they’re only 0.1 inches thick making them super low-profile for vehicles.

The pre-attached junction boxes automatically regulate energy flow with the bypass diodes to stop hot spotting. All of the components are highly waterproof meaning you’ll have no worries leaving it out in all weather conditions. And to mount the system you simply use the stainless steel rings to fix or hang in position.


  • Flexible to 30 degrees
  • Super lightweight
  • Low profile
  • Charge controller included


  • Less durability

AIZYR 400 Watt Portable Foldable Solar Panel

It’s hard to find portable solar panels in larger sizes but fear not, because I’ve got a solution.

Enter this epic folding design from AIZYR.

You’ll get a monstrous 400 watts from this folding panel so you can tap into some serious output on your adventures. When unfolded it becomes nearly 2 meters in length to absorb the sun with its monocrystalline cells. Even with its pleat design you still get a favorable 21% conversion efficiency.

When not in use it becomes pretty compact with a briefcase shape to make it easy to carry via the included handle. Plus you get a neat pocket for your cables. It will hold up on your biggest trips with a strong IP65 waterproof rating which keeps it safe from splashed, spills, and rain showers.

One important thing with this type of product is its ease of use. Happily, you do get alligator clips and cigarette lighter port cable so you can trickle charge car batteries effortlessly. In addition, a DC junction box and USB port allow for fast charging of portable gadgets like phones and tablets.

A monster of a portable solar panel. Although it is foldable, I wouldn’t fancy carrying it too far from a vehicle. A helpful option for car camping.


  • Portable and foldable
  • 400 watt panel
  • Monocrystalline cells
  • Waterproof
  • USB fast charging


  • Hard to carry very far on foot
  • Not for permanent mounting

WEIZE 200 Watt 12 Volt Monocrystalline Solar Panel

You’ll have probably noticed that most 400 watt systems use multiple solar panels. So don’t be afraid of building your own setup. You might find some better options such as this panel from WEIZE.

This option is a 200 watt product so you could hook up two sets to generate your desired output.

The highly efficient panel uses deep black monocrystalline cells for a 21% conversion efficiency for years of immense performance. Surrounding this are anodized aluminum frames and tempered glass for an impact and weather resistant build quality. This means you can freely use them on vehicles and buildings without a problem.

With a 400 watt setup like this, you could generate as much as 2kW of energy a day! 

As soon as you receive the panels they are ready to install with pre-drilled holes and junctions box. All you need to add is a solar charge controller to hook into your battery supply.


  • Add multiple to create your system
  • Durable aluminum and tempered glass
  • 21% efficiency
  • Monocrystalline
  • Weatherproof
  • Impact resistant


  • Need 2 sets for 400 watt
  • Not portable
  • Charge controller not included

RICH SOLAR 12 Volt Monocrystalline Solar Panel

Finishing up this list is an option from the reliable team at RICH SOLAR.

You can combine two of these 200W 12v solar panels for a 400W off-grid electricity supply. In my opinion, it’s a neat option to solve your problem as you can use their quick connect cables to combine them in series or parallel. 

Even on a cloudy day, you’ll still get a decent amount of performance thanks to the monocrystalline cell structure. When it comes to the durability side of things, the high transmission anti-reflective glass is reinforced and held in an aluminum frame. All the ingredients of a product will last for decades. 

If you have the space for these panels which each measure 58.7 by 26.8 inches, you can effortlessly mount them using the predrilled holes in the frame. Once fixed in position, you can forget about them knowing they’re built to withstand high wind, snow, and rain. Plus you get an epic 25 year power output warranty and a 5 year material warranty.


  • Monocrystalline cells
  • Aluminum and tempered glass
  • Combine panels in series
  • Quick connect
  • 25 year warranty


  • Need to buy 2 panels
  • No charge controller included
  • Not portable

Education: Choosing a 400 Watt Solar Panel

Let’s take a look at the factors to consider when buying a 400W solar panel.


As you might have seen, there are a number of different types of solar panels on the market. I like to split them up into three different categories – Rigid, flexible, and portable. Each of these offers a unique set of features that are suited to different uses. Here is the difference:

Rigid Solar Panels – This is the traditional panel that you’ll mostly see on building around the country. They offer tough aluminum frames and tempered glass that keep them working for decades.

Flexible Solar Panels – A modern invention that creates a bendable panel. This enables you to mount them on curved surfaces you often find on vehicles. Adding to this, they are 70% lighter and just 0.1” in height making them very low profile. With all of this, you don’t lose any efficiency either when using monocrystalline cells. They are less durable than rigid panels though.

Portable/Folding Solar Panels – These are ideal if you want to use your solar system in multiple positions and do not require it to be permanently mounted. Usually, they can be folded down and easily carried on foot using a carry handle. Ideal for cars and smaller vehicles plus they work well with solar generators. You do lose some durability with lower waterproof ratings so you can’t leave them out in bad weather.

Monocrystalline vs Polycrystalline

Let’s discuss the technical materials used to create solar panels. The part of the solar system that absorbs sunlight and converts it to electricity is called a solar cell. It is the main black or blue part that covers the majority of the surface area. This can be made up of either monocrystalline or polycrystalline.

Monocrystalline is the black colored cells that are more efficient in converting sunlight to electric energy.

Polycrystalline is blue in color and is a cheaper but less efficient technology.

Personally, I’d always opt for monocrystalline to get the most benefit out of solar power in the long run.


Solar panel system voltage is very important as you want to make sure all your different components are compatible. This includes the panel, controller, and battery. For example, if you have a 12V battery you will need a 12V solar panel or a charge controller that can match volatages. Be sure to check the product details to ensure your equipment works together. Usually, you will find 12V or 24V options.


The durability of any product is important. After all, I always say ‘Buy cheap, buy twice’. In my opinion, this is even more important when considering solar panels. The best products on the market should last for decades, over 40 years in some cases. This allows you to truly enjoy the financial benefit of free energy from the sun. 

Once you’ve bought your equipment there should be very little to no ongoing costs for your off-grid electricity. This is amazing because there are no energy bills to pay. But if you don’t purchase a durable system you will have to fix and replace parts which will be costly.

To find durable products you should look for some key elements including anti-rust aluminum frames, IP67 waterproof rating, tampered glass, ETFE covering, and multi-sheet lamination. Adding to this, the best companies will cover you with a 25 year power output warranty!


So how much do 400 watt solar panels cost?

For the panels and solar charge controller, you can expect to pay between $400 and $700. The price depends on a few elements including whether you use a PWM or MPPT charge controller. Anything cheaper than this then you should check carefully what you are getting as the product is unlikely to offer the best quality and performance.

Size and Space

Have you considered the size of 400W solar panels? They might be bigger than you expect. A single panel can measure over 5 feet in length and over 3 feet in width. This might make it tough to mount in some places. If you are using a house roof then there should be no problem, but smaller vehicles like golf carts or vans might be a problem.

Take the time to measure up the area you have available for your desired solar system and check the dimension of your panel. This can be found in the product description. 

To give you an idea you’ll need around 19 square feet per 400W panel.


For your solar system, you’ll need a number of components including a solar panel, charge controller, battery, and power inverter. Each of these pieces of equipment has a specific task in delivering you AC electricity as you get from the mains at home.

Charge controller – This connects between the panel and the battery to safely charge your battery. It helps to monitor the flow of current and protect from overcharging, reverse polarity, and short circuits.

Battery – This is needed to store the energy generated by your solar panel. Then you can draw a steady flow of electricity from the battery at any time. Without this, your power would ebb and flow with the sunlight conditions.

Power inverter – The inverter hooks up to your battery in order to convert the DC power into AC power which is needed to run most appliances. This is what you plug your devices and appliances into to make them run.

How Many 400 Watt Solar Panels Do I Need?

This really depends on your power requirements. If you just want off-grid power for an RV then 400 watts might be plenty. You’ll be able to produce over 2kWh of energy during a sunny day. That’s over 165Ah a day, so you could easily keep a set of 200Ah batteries topped up with electricity most of the time.

If you want to start powering a house you’ll need more power. Most houses will use at least 15 solar panels, and many will use 20 or 30 400W solar panels. That’s because the average daily energy consumption of a house can be around 30kWh.

Pros and Cons of 400W Solar Panels

If you’re still not sure if a 400 watt solar panel is right for you, let’s go through the advantages and disadvantages.

Produce of 2kWH daily per panelExpensive compared to smaller options
One of the highest power panels on the marketVery big for vehicles
Good for a large house roofsNot that portable (not many portable/folding product choices either)
Rigid panels last for decadesNeeds a more expensive charge controller
Fewer points of failure

Solar Panel Maintenance Tips

Most of the time solar panels need very little maintenance. You can set and forget.

That being said, there are still a few things you can do to help increase electricity output and extend the lifespan. Here’s some maintenance tips for you to consider:

  1. Clean your solar panels

It’s important to clean your solar panels when they get dirty. The simple reason is that anything blocking sunlight hitting the solar cell directly impacts performance. Often problems like dirt, dust, grime, leaves, snow, and bird droppings can cover your panels. Make sure to clean this off to restore performance. A tell-tale sign of dirty solar systems is a reduction in electricity output even on a sunny day.

  1. Fix errors

Any damage or errors in your solar kit should be fixed as soon as possible. You should regularly check your charge controller and power inverter for any error signal on the screen and LED lights. If you see a red light, don’t ignore it! Common issues can be fault/dead batteries, overloaded power inverters, broken wiring, and incompatible components. Not only will these problems lead to a drop in power and damage to your appliances, but they could also present a fire safety risk. If you’re not sure consult a professional to resolve your fault.


How many batteries for a 400 watt solar panel?

A 400w solar panel might generate up to 200Ah of energy on a very sunny summer’s day. This means it is best to have at least this amount of battery storage to fully take advantage. You might want between 200 – 300Ah worth of battery storage which would mean 2 or 3 100Ah batteries or 6 50Ah batteries.

What charge controller is best for a 400W solar panel?

A 12V 400W solar panel can generate a maximum of 33A so it is best to use a 40A solar charge controller. If you want to connect more solar panels you will require bigger-sized controllers. To calculate amps you divide watts by voltage. So 400w / 12v = 33.3A.

What power inverter to use with a 400W solar panel?

With a 400 watt solar panel, you should use at least a 400 watt power inverter. In reality, you will want a bigger inverter than this. It depends on how much power your appliances will draw. It is best to use at least a 1500 watt inverter so that you can run a number of devices at once such as mini-fridges, computers, phones, TVs, games consoles, and cooking appliances. Bear in mind, you will be able to store a lot of energy in large 100Ah+ (1.2kWh) batteries but you can only replenish at a maxim of 400 watts from each panel per hour. If you want more information read ‘What is a Watt?’ for a simple guide.

Final Words on 400 Watt Solar Panel

By now you should be an expert on 400 watt solar panels. 

Together we’ve been through everything you need to know from how much power you can generate to the best 400 watt solar panels available today.

Whatever you decide, the benefits of adding solar energy to your off-grid electricity supply will be a big benefit. 

You can happily select from the products listed above to best suit your needs.

I hope you enjoyed this in-depth guide to 400 watt solar panels.