If you are interested in solar power but don’t know how many panels will fit on your roof – or even how many solar panels you need – this guide is for you! 

When considering your home’s roof space, there are 3 things we take into consideration:  

Your Energy Usage 

Your solar system size is determined by your energy usage, not the size of your home. We’ve seen small homes with many panels and large homes with only a few panels.  

In Wisconsin, there is no financial benefit for oversizing your system. We currently have net metering policies, which means your overproduction is sold back to the grid at a reduced rate (much lower than the rate you sell your direct production offset for).  

For this reason, energy usage determines system size. When you get a free, customized quote from Arch, we maximize 100% offset using the roof space you have. 

Click here to see a ballpark pricing and size list for your system. Please note: every system is different and customized in design and price. 

Your Roof’s Orientation 

The most ideal roof for solar is an unshaded, south-facing roof. It’s still possible to put panels on an east/west-facing roof structure, but you might need more panels to offset your total electricity usage.  

For instance, if you have a 6kW system (roughly 15 panels), it’s possible all 15 panels could fit on the south-side roof and cover your electricity usage for the month.  

If you have an east and west-facing set-up, those 15 panels may be split between the two roof faces to reach maximum sun potential throughout the day.  

So, the amount of roof space will be determined by how many panels and the cardinal orientation of your roof.  

Here are some examples: 

Southern roof, all panels fit on one unobstructed space. 

East/West roof with some obstructions. 

Obstructions and Setback Requirements.  

If your home has vents, gables, or other obstructions, those will impact the overall design of your solar array.  

Each Wisconsin municipality has different rules to follow, and our team of energy experts and engineers works with each jurisdiction to design your array to code. 

If a roof face has too many obstructions, we may need to split panels on multiple roof faces to fit the amount of solar needed to offset your usage.  

Southern roof with split panels due to obstructions. 

As we consider these roof conditions for your solar array, we also make sure the panels will fit desirably. Some folks don’t like their panels to be visible from the street, which can also affect the roof space we can use for solar installation. 

How big are solar panels? 

The size of solar panels can vary, but many solar panels are about 5ft in length and 3 feet in width. One of our preferred panels – The REC Alpha Pure 410s – measures 71.7 x 40 x 1.2 in. 

Your roof needs enough space to accommodate these 5×3 ft panels and leave enough room on the edge of the roof for fire code. 

Every house is different, so cookie-cutter solar proposals are never a good option. If you are curious how much roof space you need for solar, it all starts with the size of your system.  

Reach out to Arch today for a low-pressure, free proposal. We’ll show you the best placement for maximum sun exposure on your roof.  

If you aren’t sure about a roof install, there’s always an opportunity to explore ground mount solar as well!