ReVision recently worked with Cumberland County to install a 10.2kw solar electric system on a 9-11 communications center.
Cumberland County Communications Center
Enphase offers robust web-based data monitoring. Features include time lapse view of system performance, historical data performance download, and carbon-offset information such as equivalent # of cars not driven based on system performance.

ReVision recently worked with Cumberland County to install a 10.2kw solar electric system on a 9-11 communications center. The photovoltaic system, paid for in large part by a state grant, will offset energy use at this mission-critical facility in Southern Maine.

While the southern exposure of the building was perfect, the site did have one challenge – two large communication poles on the south side of the roof. These poles cast a shadow that tracks across the roof at different times during the day.

This is a problem for a solar array with a typical string inverter because this small amount of shading would bring down the production of the entire array, even though just a small portion of the roof is shaded.

To overcome this challenge, ReVision used Enphase micro-inverters. Enphase is a unique product which allows each module to in a sense act as its own individual array – so that shading of one module will not bring down the performance of others.

How String Inverters Work

Usually, all of the panels on an array are linked and wired so that the direct current (DC) that is generated is delivered to a single inverter that converts the DC into usable and familiar AC power. This inverter typically lives near the building’s regular electrical panel.

In the case of Enphase, each solar module acts as its own inverter – so AC is passed downstream from the array directly to the electrical panel. And when one solar panel is shaded, rather than compromising the production of the entire array, only the production of that affected solar panel is reduced.

Enphase also includes robust data monitoring software that generates a time lapse picture of the day’s solar performance. This information will be used by Cumberland County to better understand the performance of the system and its impact on their energy usage.

The 10.2 kw array will generate an estimated 14,000kw/hr each year, enough energy to power two ordinary homes, and offsetting nearly 10,000 lbs. of C02 emissions. So far, the system has displaced enough C02 to take 90 cars off the road for a day.
[zenphotopress album=228 sort=random number=5]


Jim Jenal says:

Very nice article about the value of micro-inverters. We have used them on a number of our installations that had similar shading issues – places where we frankly could not have done a string inverter installation – and they are performing beautifully. In fact we are seeing between 10 and 25% higher yields compared to what was predicted for that shading using the CSI calculator.

Fred says:

Thanks for the feedback, Jim – we’re taking a cautious approach (real-world evidence over hype) but so far have been happy with the results of micro-inverters, especially when they help us in situations which otherwise might be tricky!

Leave a Response

Your email address will not be published.