Can My Building go Off-Grid?

Written By: Randy Anderson Technical Sales & Training Manager

The question often comes up about the viability of running commercial operations off-grid on stand-alone solar, inverter and battery systems. Although every system and application is unique and different it is absolutely possible to do this.

Recently we commissioned a system in Northern Canada that was installed on a new 4 bay highway truck maintenance shop that would also serve as a micro grid for the adjacent EMS facility, refueling station and crew quarters.  The purpose of this solar system is to reduce generator run time and fuel consumption as the existing operation was relying on generator 24-7 regardless of load. This means that much of the time the oversized generator would simply be running at idle with very few loads to run. This is not an efficient operation of a generator.

The new building was fitted with 21.8 kW of solar modules, 4 x 6.8kW Schneider Electric Conext XW inverter/chargers and a bank of Discover 48 Volt, 4872Ah, 2 Volt Flooded Tubular Cell batteries. Along with those we added the balance of system components, charge controllers, battery monitors, automatic generator start module, system control panel and a Schneider Electric ComBox.  It was estimated that the average continuous load on the system would be 8kw with the inverter maximum continuous output of 27.2 kW and 60 second surge capability of 48 kW. The system was programed for a battery discharge level to 50% DOD which would yield almost 3000 cycles at which point the CAT Diesel Genset would engage if the solar modules were not yielding enough power to sustain the load.

In this example there is only a couple weeks of data so the precise annual fuel savings will not be known for some time. It is estimated that the generator may run for an average of 3-4 hours per day in winter and possibly not at all in the summer months, weather prevailing.  CAT states the fuel consumption of the 44 kW generator at 50% load (its lowest fuel consumption rating) is 51.5 liter/hour, if diesel fuel was at $1.00/litre and we reduced the generator run time to 12 hours per day then annual fuel saving would be $225,570. 

Is it possible to operate a commercial facility off grid?  In this case, not only is it possible, but also the customer stands to save upwards of $1.8M in fuel over the 8-year life of the batteries.

We think that’s a pretty good reason for you to look into solar further. Contact us with any questions or to receive a quote.