400 Watt Solar Panels: Are they Worth It?



Most residential and commercial solar power systems consist of 250-350 W modules. They are a good combination of power generated per panel and price, but they may take up too much space. If you have any space constraints, 400 watt solar panel are what you really need.

Every PV module is made up of smaller units called solar cells. For 250-350 W panels, their number is usually 60 or 72, while 400 watt solar modules can have 120 or even 144 cells. That doesn’t mean, however, that 400 W panels are twice as big as 300 W ones. In fact, they are the same size. Such compactness of high wattage solar panels is achieved due to the half-cell technology, which cuts full cells into half, reducing their resistance. Lower resistance means more energy is being captured and produced.

An average solar panel size is about 20 square feet. And here is where the advantage of buying 400 W panels becomes clear. For a typical 6 kW power system made of 400 W panel you’ll need about 300 square feet available on the roof of your house. If you decide to go for 300 W panels, you’ll need to find some more 100 square feet to install them all. The less panels you have, the bigger chances are that they fit into the sunniest side of the roof.

Such high wattage modules tend to be more efficient as well. Solar panel efficiency shows solar panel’s ability to convert sunlight into usable electricity. While ordinary solar panels’ efficiency is around 15-18%, 400 W modules typically exceed 19-20%. It means that more sunlight will be harvested by each module.

It would be a mistake to think that 400 W panels are absolute leaders in the market. They do have one significant drawback – the price. Such modules are normally 20% more expensive than lower wattage counterparts. On the other hand, as we have already mentioned, the more powerful the panels are, the less of them you need. It may turn out that the overall system cost is less when going for 400 W modules instead of conventional 300 W solar panels.


No matter how efficient 400 W solar panels are, the amount of electricity they generate will also depend on some general factors, such as:

  1.  Number of peak sun hours (PSH) in your area
  2.  System type: the most popular grid-tied systems cause about 15% electricity loss
  3.  Shaded conditions: clouds may decrease panel efficiency up to 25%
  4.  Direction solar panels face
  5.  Angle: a roof tilted at an angle of about 30 degrees is considered to give the best performance
  6.  Material used (monocrystalline or polycrystalline silicon), wiring and busing (busbars), reflection (glass layer on top of silicon solar cells).

To wrap it up, there are a lot of factors to keep in mind when choosing the right solar equipment. 400 watt solar panels can make sense for some property owners who have space limitations. While such options are more expensive than lower wattage modules, you will need less of them to cover your electricity needs.

400 Watt Solar Panels: Are they Worth It? was last modified: by