The owners of the array have an unusually high household electric bill. They have already made a number of energy improvements in the home. They also want to move to electric heat, via some type of heat pump, which will increase the load further. The roof space was not large enough to meet the final expected demand so they made a decision to ground mount the array. This 36 module system was designed to offset most of their load. If additional modules were needed to cover the electricity needed by the heat pump then the roof would be utilized.
The homeowner monitors his system performance. Enphase micro inverters make this really easy with a wonderful web site that provides both a visual representation of the array as well as reports, graphs, exports, and a monthly summary email. To make it easier to compare to his CMP bill the homeowner had CMP reset his billing cycle to match Enphase's monthly time module. In 2013 this system produced 11,344 kilowatt hours of electricity or about $1,703. Of course our electric rates are going up in March 2014 so savings will be greater every year. As of January 2014 this system had produced 110% of expected output.
Ground mount arrays have many advantages. They can be oriented perfectly south and at the idea angle to optimize annual output. They are perfect if you have a small or shaded roof. This install uses Enphase micro inverters that are mounted on the back of each module. Ground mounting makes they very easy to access should they ever need maintenance. We generally don't recommend cleaning modules but in Spring when we get the heavy yellow pollen it can impact PV performance. If we don't get rain it is easy to wash ground mount arrays. While this array is fixed there are pole mounts that allow the modules to track the sun. These can increase production by 30% or more. They add cost and maintenance so many times it is less expensive to just add more modules.
At this install we poured concrete footing but newer racks are have heavy ballasts and do not require ground penetration, thus saving labor. There also screw and other type anchors that speed up install time and save you money. We then built the frame from 3" galvanized pipe. Iron Ridge solar rails were then installed and then the inverters and modules.
Contact us today with your questions or to set up your free consultation.