Key Photovoltaic Information for Purchasing Your System
When having a photo-voltaic system (PV) installed on your rooftop, be sure the job is done with racking systems and flashing that meet the International Building Code. Modules, for example, must be installed so that the units don’t “fly off the roof” during high winds. To ensure against this, roof penetrations are made to secure the racking system for the modules. Each attachment needs to be flashed properly so that the roof does not leak. Simply caulking around penetration is not an acceptable solution.
Most manufacturer warranties guarantee that after 25 years, their modules will produce at least 80 percent of what they did when first installed. The 25-year warranty is not a construction product warranty indicating how long the module will last. Do not be confused by what these warranties are providing.
Studies have shown that the energy produced by PV modules depreciates on average about .7 percent per year. Some manufacturers have a track record indicating a better performance than this average. Check to see how long the manufacturer has been producing PV modules.
Real module efficiency is shown by power tolerance, peak power, or pmax rating. A 230-watt module with a pmax rating of +5/-5 is telling you that the panel may exceed the rating or it may provide less energy, up to as much as 5 percent. The module may only produce 219 watts rather the 230 watts listed on the module. These systems will produce less energy than what you have been led to believe.
Because solar modules sit on rooftops, they are constantly exposed to the effects of a corrosive and harsh environment. This constant exposure to nature’s elements impacts the quality of the packaging that surrounds the cells, resulting in packaging degradation.
This affects the function and integrity of the module. It can also lead to performance issues such as poor energy production, array performance failure, and safety issues that includes electric shock hazard. Examples of packaging failures include glass breakage, metal frame breakdown, dielectric breakdown, bypass diode failure, encapsulant discoloration, and backsheet cracking and/or delamination. Electrochemical corrosion can be introduced to the module because of the failures in the packaging, causing the degradation of power output/performance and ultimately module failure. Because of Hawaii’s harsh environment, homeowners may want to know more about what makes a particular solar module sturdy enough to provide the service life expected.
Homeowners should also be wary of sales talk that promotes the manipulation of the state tax code by providing you with credits you don’t deserve. If you have questions about the tax code, go to the state’s Department of Taxation website and learn more about renewable energy tax credits.
The purchase of a photovoltaic system is not only a price issue. The quality of the module, the installation/flashings used on the roof, the manufacturer’s track record, and a contractor’s attention to detail should all be considered.
Contact Pacific Islands Construction for a consultation or visit our website at pacificislandsconstruction.net. Our goal is to provide complete satisfaction to customers, now and into the future, by equipping them with the finest in solar energy systems.