A Solar Solution for Winkelman Building Corporation

   

This innovative solar electric solution is part of the beautiful new office complex designed by, built by, and built for Winkelman Building Corporation, a leading commercial/industrial, and design/build firm located in St. Cloud, Minnesota. The photovoltaic panels attach directly to the metal roof via a permanent adhesive, rather than traditional metal structures such as frames, supports, or tracking mechanisms. This building-integrated solution is state of the art for the solar industry and is designed to allow solar electric sources to be efficiently and economically installed on virtually any commercial, industrial or residential building.
 

Winkelman Building Corporation (WBC) has been a leading commercial and industrial general contracting firm in the Mid-west since 1969. From the beginning, WBC has used their expertise to offer construction management and customized design/build services in the private and public sectors.  Their slogan, Building Solutions for Changing Times, is reflected in their adoption of this new energy source.  One of the reasons for this innovation is to make the WBC office building a functional display for other building owners or contractors to get “hands-on” experience with the latest energy solutions.  With rapidly increasing energy prices, utility deregulation, and increasing power outages, this type of building-integrated energy solution is becoming very attractive in the world of today.  

The project begins with careful planning. The solar panels must be places in a spot on the roof with maximum sunlight and virtually no shading. David Winkelman of WERC (left) and Ralph Jacobson of Innovative Power Systems (right), measure the shadow cast from near by trees and buildings with an instrument called a "solar pathfinder". The instrument literally tracks the sun's angle and can project the suns position year round. This is very important information because the sun's path is lower in the sky during the winter as compared to the summer months. As a result shadows cast by nearby trees and structures may be augmented by the sun's lower path in the winter. Why pay for a solar panel installation if it's not going to be in the sun, right?

Having decided the location of the solar panels, next, we find a suitable location for the inverter and the wiring. Gary Fink from Smolnik Electric of Sauk Rapids, roughed in a spot for the SunnyBoy 2500U inverter from SMA-America. This inverter will take the DC current from the solar panels and convert it to AC current for use in the building and to sell back to Xcel Energy when the system produces more than is being used in the building.

This is the SunnyBoy 2500U inverter we used at the Winkelman Building Corporation installation. Capable of producing up to 2500 watts of electricity, this unit will sell power back to Xcel Energy when the building is using less than the solar panels are putting out. When the building is using more than the solar panels are putting out, the power is consumed in the building. In effect, this solar installation is a miniature utility company!

These inverters are made in Germany, and are rather robust. They can handle an input voltage up to 600 volts from a solar array which means higher efficiencies and smaller wires from the solar panels to the inverter. Unlike other inverters on the market, the SunnyBoy inverters are a "current source" rather than a "voltage source", which means that unlike other inverters, the SunnyBoy won't produce harmonic distortion on the power lines and therefore, is more efficient.
With the inverter mounted and the wiring run, the next step is installing the flexible solar panels on the standing seam steel roof. This is a standard roof! Installed by Granite City Roofing, this is a typical metal rooftop that will last a lifetime. The roof cap (the ridge flashing) was modified slightly to accommodate the electric junction boxes by Granite City Roofing, who incidentally did an exemplary job at an attractive price.  This is very nice because it means any building with a standard standing seam metal roof can have a solar electric solution like this one installed.

The solar panels are attached to the roof with an adhesive designed to bond to the metal roof. The panels are available with the adhesive already applied, or without. We used the panels with the adhesive already applied because it dramatically cut the labor necessary to attach them. These panels are from Uni-Solar, and must be installed by a Uni-Solar certified installer. Ralph Jacobson of Innovative Power Systems in Minneapolis, Minnesota was our certified installer.

A very nice feature of this system, is the real-time readout from the SunnyBoy control unit. This sign in the lobby displays the current system output in kilowatts, the total energy produced by the system on that day, and the total energy produced by the system since it's commissioning. One of our goals with this installation, is to provide real data from a solar installation. At present, the only data available is from the manufacturers of the components. As such, these numbers will always be weighted to favor optimal conditions. Our data is real data from an actual system, installed and working. With this data, manufacturers may be able to produce better solutions to power tomorrow.