In choosing a product, your first concern should be whether the manufacturer will survive the length of the warranty offered. In other words, will they be around in the next 5, 10 and 25 years.
Solar Wave researches the financial viability of the manufacturers we offer products for. While this is public information, there are also industry trends and publications that shed light on this issue. While we cannot self-guaranty the product, we do believe the companies we buy product from will survive.
There are three main products you will need to select for your system namely, the inverter, panels and racking. Below are some of the options we offer.
Hawaii is a leading state for the adoption of microinverters, manufactured by Enphase. In Q2 2013 Power One came out with a 250 watt microinverter which matches well with panels in the 250 watt and more range. Power One also has a 300 watt microinverter well matched to the Sunpower panels in the 327 watt classes
Individual panel monitoring
Lower starting voltage leading to more power produced
A 25 year manufacturer warranty
Reduced performance loss from shading or different roof faces as compared to string inverters
About 20 cents more expensive per watt (dependent on size of the system)
Concerns about whether the electronics can handle 25 years of being in the high heat caused by the sun
Increased false positive alerts
Having men on your roof to service, and being more expensive to service over lifetime
String Inverter Pros:
Less electrical interconnection work for larger systems
You can install a larger inverter than you currently need for a nominal amount more and less expensive phase II costs
String Inverter Cons:
No individual panel monitoring
Only a 10 year manufacturer warranty
Bulky backpack sized device must sit on your wall, and slightly less output
There are two classes of panels, high and standard efficiency. The high efficiency panel class is dominated by Sunpower and Panasonic. The Sunpower warranty is industry leading as they include labor and performance. All other manufacturers limit themselves to a performance warranty. With high efficiency and best warranty comes added cost.
Standard efficiency panels have wide ranging performance efficiencies. Solar Wave selected panels are based upon the perceived strength of the manufacturer and solid efficiency numbers.
There is a simple answer to what is better. If you have the roof space, you can use the standard efficiency panel and add more panels with the price differential.
The high efficiency panel system may cost 25% more for a less than 10% performance advantage. You could add a few extra standard efficiency panels for a significant cost savings.
In contrast, the Sunpower panel warranty, high efficiency, and lifetime cost will make up the 25% initial cost. If you have a limited amount of roof space, the high efficiency panel is a viable choice. The labor warranty is a considerable factor in this choice.
In the same 18 square feet the standard efficiency panels may be 240-255 watts while the high efficiency panel would be in the 327-345 watts.
Pro Solar 3" rail is our leading rail choice as it is designed for commercial applications. Lumos' Xflash and Quick Mount roof attachment systems are used depending on the roof type you have. Both have excellent water proofing methods.
Commercial roofs types differ from residential applications. Pro Solar has proven roof attachment hardware. There are many other choices as well. The site inspection will quickly tell the designers what choices are available.