Low Wattage Solar Panels (How To Choose)

When it comes to solar panels, many people may mistakenly believe that bigger is better, and this is not the case – as it is with most other things in life. While you can get larger wattage solar panels, the lower wattage ones often make more sense from an investment and ROI perspective.

Solar panels come in various wattages, from as little as 3W to 500W, and most residential PV installations average between 290W and 320W. Lower wattage mobile or portable panels are used for smaller devices like mobile phone chargers, laptops, and wifi routers.

Let’s look at the benefits of using lower wattage panels in different applications :

  • Why lower wattage panels for your home could save you big money
  • What is solar panel efficiency
  • What do you use low wattage solar panels for
  • What’s the best wattage for a solar panel

Let’s dive into this now so you can better understand more about low-wattage solar panels and the benefits they can offer.

Why Use Lower Wattage Solar Panels For Your Home?

Opting for the lower wattage panels for your residential installation can save as much as 50% on the generation costs of your system.

When considering what size solar panels to install for your home, you also need to consider the generation cost. This is the cost per watt incurred, and you work it out by taking the dollar price for the panel and dividing it by the wattage to get the cost/watt.

Cost Per Watt

So, for example, a 320W solar panel priced at $200 would equate to $0,625 per watt, which is the generation cost you need to look at. This price does not include the installation, mounting, or connection costs.

If your solar array has ten panels and each panel is 320W at $0,63 per watt, that will cost $2016- 3200W @$0.63/W.

If you take a bigger wattage panel of around 400W at approximately $420, the cost per watt there is $1,05!

If you extrapolate that to the same generation capacity of 3200W, that would be eight panels, which will increase the generation cost to $3360, which is 67% more expensive for the same power.

That’s a fair whack of cash overspent, and that money saved can be used for other components and installation.

See also: Solar Panel Sizes and Wattage: A Comprehensive Guide to Making the Right Choice

Picking The Best Wattage Panel For Your Home

As you’ll see when we look at panel efficiency, and as we’ve seen from the cost per watt, the bigger wattage panels are not always the best option, so you need to have that discussion with your installer or supplier when the energy requirement assessment is done.

The wattage and quantity of the panels you require will depend on the size of the system and the roof space available to determine the size of the panels required. It will also depend on the existing roofing structure and whether it can take the weight of the array.

So smaller wattage panels which are generally lighter, may work to distribute the weight of the array evenly and put less strain on the roof than larger, heavier panels would.

Another factor to consider when looking at low-wattage panels is their efficiency. Using panels that aren’t efficient will mean more panels and more money, with less generation capacity- and this applies equally to high and low wattage panels.

Why Is Solar Panel Efficiency Important?

The capacity and ability of solar panels to generate electricity are relative to how efficient they are at generating power using the available solar energy.

Modern-day solar panels have an efficiency of between 15% and 22%, improving all the time as technology develops. So whether you have eight 400W panels at $1.05 /W or ten 250W panels at $0.63/W rated at 22%,  you still get the same efficiency and generation, just at a lower price.

The highest efficiency of any panel is just under 23%, so most solar panels will be in the 20%-22% efficiency range.

Small solar panel in a garden

Where Are Low Wattage Solar Panels Used?

Low-wattage solar panels can have as little as 3W power generation, and these are typically used to trickle charge batteries that power small low voltage devices.

These panels are much smaller than those found on a residential PV array roof and are usually portable and easy to pack and store in vehicles, campers, and RVs. They can have their stand or simply be laid out on a table or roof of a car or trailer to generate electricity.

They don’t require an inverter, and low wattage panels like a 3W-10W are often used as trickle chargers for 12V batteries powering electric fences, vehicle batteries, or electric gates.

Even 10W panels are used for this purpose as they simply don’t generate enough current to power devices, even a mobile phone. Still, they are pretty efficient as trickle charges to maintain larger batteries’ voltage and current levels.

As the panel gets bigger, they can be used to provide power rather than acting as a trickle charger. A 20W solar panel can power small devices such as cellphones, LED lights, security cameras, and mini-pumps.

From 50W upwards, low wattage panels can charge batteries faster and power smaller devices such as DC TVs, laptops, LED lighting, and even small DC pumps found in camp showers.

You can even build an array of low-wattage panels connected to a charge controller and a battery to provide a source of AC power when outdoors, on a boat, or even at your home.

What Is The Best Wattage For A Solar Panel?

This is going to depend on the application. For home or residential systems, solar panels are usually rated at between 290W and 320W, but you can get panels of 500W or more if necessary.

Larger wattage panels that are efficient can reduce the number of panels needs and are helpful where roof space is limited, and power generation capacity needs to be met. So, for example, when a home needs 3kW of power but only has enough space for six panels, 6 x 500W panels can be used.

Where space is not restricted, the maximum number of panels at optimum cost per watt can be used, and for mobile applications like camping, the wattage would again depend on the power requirements.

When it comes to low-wattage solar panels, the applications are vast and offer the user various wattage and efficiency options to best match their desired power results.



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Elliot has 20+ years of experience in renewable technology, from conservation to efficient living. His passion is to help others achieve independent off-grid living.

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