31 kW Commercial Photovoltaic Installation- Uni-Solar PVL with Nextek Power Gateway Controllers and Cobasys NiMH Batteries. Satcon and Exeltech Inverters


	228 Uni-Solar PVL 136 watt laminates mounted on SFS (solar flat system) ballasted system Used on ballasted commercial flat roofs. 27kW's feeds the 30kW Satcon inverter shown below. This inverter has 480V 3 phase output. 3.2kW's of the PV (24 laminates) go to Nextek Power Gateway controllers. 2 of the 5 Power Gateway power office lighting, while the other 3 power an Exeltech inverter to run critical loads during power outages. (Click solar array for larger pictures)

Satcon 30kW Inverter- 480V 3 Phase Inverters come in all shapes and sizes. This single inverter has enough capacity to take the 500+ volts of direct current electricity from the solar panels and convert it to three phase AC power to feed the building. This is a UL1741 compliant inverter that synchronizes to the electricity from the utility to seamlessly feed clean, PV produced electricity into the 480/277 volt panel. Click the inverter to see more.

	Nextek 48V Combiner Box with MPPT Two nominal 24 volt laminates are series wired to get 48 volt nominal battery charging voltage to feed the Nextek Power Gateway (shown below). The two aluminum boxes in the combiner show Nextek's Maximum Power Point Trackers, which lock the solar voltage to the level that corresponds to maximum power output. (click combiner box for larger photos)

Nextek Power Gateway Controller These controllers are an exciting new technology that manages three sources of power. They can pass photovoltaic DC current straight through to DC lighting to get more usable energy through higher efficiency. Converting to AC at an inverter and back to DC at a light fixture is inefficient. These controllers eliminate both conversions. They can also power the lights using utility power (208 or 277V) or with battery power. They use the cheapest source available at any given time.

	Exeltech 2kW Pure Sine Wave Inverter This inverter outputs a pure sine wave to supply backup power for critical computer servers. The Nextek power gateways can supply it 48VDC from the PV (photovoltaic), Cobasys NiGuard battery bank, or rectified 277VAC. Click the inverter for more photos.

Cobasys NiGuard NiMH Batteries Cobasys, is a sister company to Uni-Solar. They provide the backup power for this installation with their Nickel Metal Hydride batteries. NiMH batteries take up less space than their lead acid counterpart as their energy density is greater. They also have no memory problems and can be drained completely without sustaining damage. These are the ultimate for backup power and are currently only available for large commercial installations. Click the batteries for larger pictures.

	Data Logging and Display- The grid tie inverter communicates DC and AC energy to a data logger that displays output in the lobby of Automation Alley. The logger also collects weather data including insolation. The system includes a camera to view the solar installation. Click "site view" on the introductory screen at the data web site (after logging in as "guest" without a password). Click "main" to view the data screen. Note that not all windows are available to user "guest". Click the data photo for more.

Commercial Expertise Funding for this demonstration project required that a portion be visible from the ground. 36 of the laminates were installed on a frame built and designed by S.U.R. Energy. SUR Energy Systems has the financing, expertise, and trade skills to make your commercial installation go in smoothly and work properly the first time. Click the array for larger images.

This project is at Automation Alley in Troy, MI (Michigan)