Well, maybe not YOUR roof, but you would be surprised at how many people we have to let down. Not every roof is great for solar panels. This can be a big disappointment to homeowners. Believe me – we are equally disappointed in knowing that we have an eager client’s goal that we cannot fulfill.
There are several things that can make roofs unsuitable for solar panels:
Lots of Chopped up Small Roof Sections
This is the most frustrating answer we have to give people. The larger and more expensive the house, the more chance you will have a lot of smaller roof facets. This is an architectural choice. It may look great, but solar panels are big and rectangular. Hip roofs and many small roof surfaces reduce the number of panels that can fit on any given roof surface. And it’s much more expensive to install solar panels on many roofs. You have to run electrical conduit through the attic to each roof surface. If that is not possible, which is often the case, surface mounted conduit must be used, which most people would rather not see.
Two-story roofs are much smaller when you consider the footprint of the house. A 2-story house has roughly half the roof space of a 1-story house of the same square footage.
Shading from Trees
This one is pretty obvious. Trees often shade rooftops. We don’t like recommending the removal of trees unless they are already a nuisance or dangerous. Many times it is a beautiful Royal Palm or very tall tree that casts a long shadow that wipes out large areas of usable space. Shade is devastating to solar panels. Frequently, neighbors’ trees can shade your roof. While you may have a friendly neighbor now, what happens if they move and the next owner has different ideas. It is important to take the future into consideration. And removing trees can be costly.
Shading from Other Building Surfaces
If you have a raised entryway, multi-story house, or split-story house, you will likely have shading on some roof surfaces from the building itself. While a roof surface might have full sun in the afternoon, what about the morning? These shading impacts must be considered. The return on investment goes down dramatically in partial shading situations.
Other surfaces that cast shade are chimneys, electrical service entrance masts, and even plumbing and range hood vents.
Shading from Other Man-Made Objects
Nearby towers, tall buildings, or even utility wires may cast shade. You might think that electrical wires are too small to matter, but they are not. We have ways of mitigating these effects, but these are considerations nonetheless when determining whether a roof is suitable.
There are building code offsets that may prevent solar panels from being installed in certain areas of your roof. This depends on the jurisdiction in which you live, but it can wipe out large areas of usable roof.
Solar panels placed near the edges of roofs, particularly roof gables, are subject to engineering design pressures that are extraordinary. The required structural spacing between attachments may make areas of the roof unusable, but more often the limitation is the solar panel itself. There are very few solar panels on the market that are tested to the highest wind ratings, and even those are off-limits for some roofs in some areas. If you are within 1,500 of the shoreline, the engineering challenge is difficult. If you are within 600 feet, the challenge becomes severe or impossible in some cases. Taller roofs and homes in areas sparsely populated also have increased requirements.
It’s Too Steep
Technically, no roof is too steep. You can install solar panels vertically. The question becomes whether it is economically viable. Installation on steep roofs is extremely dangerous and challenging, increasing costs. Steep roofs also perform relatively poorly in Florida and are more susceptible to shading impacts. Depending on the type of roof you have, it may be extremely difficult or impossible to work on it depending on the material.
The Roof Type Makes It Inadvisable
Certain roofs like glazed tile, metal tile, stone coat metal, slate, copper, and other specialty roof types are not conducive to solar panel installation, or it can be very expensive. There are exceptions, like installing solar panels before the final roof membrane is installed. However, for the most part we recommend you stay away from solar panels on certain roof types. There are serious considerations when installing on flat roofs, especially commercial flat roofs. Ballasted (weighted) racking systems are not popular in Florida due to the amount of ballast required to meet wind uplift requirements. Although, there have been advances in this technology that increase the viability of some roofs.
The Underlying Structure Is Not Suitable
If the underlying structure cannot sustain the dead weight or the wind uplift of solar panels, it will not be suitable. Certain structures like pole barns, open structures, sheds, aluminum enclosures, some manufactured homes, and other buildings are simply not robust enough to mount solar panels safely and within the building code’s requirements.
But Someone Else Is Willing To Do It
We get this all the time. So many times we have to break the news to clients that their roof is not suitable, or at least it is not advisable to install solar panels. Clearly we don’t like to turn away good business, but it is our duty to inform clients properly.
Why would others be willing to do it?
The foremost reason is that our clients are usually talking to a salesperson – usually an independent contractor. They often really don’t have the technical expertise to determine whether roofs are suitable. Moreover, a good number of them simply don’t care what happens when the contract gets turned over to the contractor. They have no downside to making a sale, only for the contractor to later cancel it if they do the responsible thing and turn away the business.
And sometimes contractors are just downright shady. They will install solar panels in all kinds of places where they don’t belong.
Often you will find that you sign a contract and the contractor shows up for a site evaluation, only to determine that the installation just won’t work, or they can’t do it as contracted.
Many solar companies are really just solar sales organizations. They often use substandard tools to perform sizing and system layouts. We use industry-standard tools coupled with proprietary processes that we have developed to ensure accuracy before we ever step foot on your property.
If we are telling you that your roof is not suitable, it is for one of two reasons. Either you simply do not have the space to meet your goals, or it is inadvisable from an economic perspective. It is our goal to have happy clients, and it does us no good to steer people into an investment they will regret. We try to let people down easy, but we also understand how frustrating it is to hear bad news.