With Washington DC offering homeowners the best solar incentives in the country – its small wonder that solar panels are going up like hotcakes. In order to meet the demand, most solar installers are adept at designing and efficiently installing solar panel systems on most roof types in DC: namely flat roofs and asphalt shingle. However, homeowners with a traditional slate roof will need to shop around for a qualified, slate-savvy installer.
Slate Roof Challenge
In this order, the most common types of residential rooftops in Washington DC are flat, asphalt shingle and slate. Asphalt shingle are generally the simplest type of roof to attach to. They are flexible, soft and flashing/sealing all of the attachments has been fine-tuned to near perfection by the solar industry. Flat roofs are generally installed using no/few penetrations either with parapet-to-parapet rails or ballast-weighted systems. Slate, however, is among the most challenging roof type to work on for the following reasons:
Expertise Tools and Labor Required
Training a work crew adept at installing solar on a slate roof takes a significant investment of time, tools and techniques. As slate is a type of stone material – specialized diamond-tipped drills and copper replacement nails are required to penetrate and reattach the slate; drill too fast – and you’re likely to break the slate. Even with the most cautious of installers, a number of slates are still likely to end up broken and spares need to be kept on hand. Ideally – artificial slate can be used for replacing broken slates. Specialized flashings designed for use with the larger slate tiles must be used to seal around the attachment.
Due to the fact that slate is essentially a smooth, slippery thin stone – this can be particularly challenging for installers to navigate. Couple this with a steep pitch, and extended hours on the roof due to time-consuming drilling techniques, labor estimates can easily double or triple when compared to an asphalt shingle roof; not to mention a particularly challenging and long day(s) for the installation crew.
The above two points ultimately result in increased costs for the customer. Fortunately, for DC residents with slate roofs, the financial incentives are such that paybacks are still generally under (or around) the 5 year mark – with many years of clear income to follow. Furthermore, as slate roofs can last 100 years or more, the roof and solar combination is set for a minimum 25 year relationship – and likely a good decade beyond that.