21.62 kW Solar Electric System Installed in Newfield, NY

Tuesday, November 1st, 2011 by Hal Smith

Challenge

This Newfield Bed and Breakfast was looking for us to install some solar panels!

Solution

This 21,620 W system (21.62 kW) grid-connected solar electric system was installed as two arrays at the Bed & Breakfast. To work with the available space, one array was placed on the barn roof (9.2kW) and the other larger array was placed as a ground-mounted system (12.42kW).

This 9,200 W (9.2 kW) grid-connected solar electric system was installed as a roof-mounted array of forty (40) SunPower 230W solar modules on the Customer's south facing barn roof (190° azimuth, 55° and 15°pitches). The modules were mounted flush to the roof surface using a UniRac SunFrame mounting system and alumninum U-Channel to increase air circulation and system performance. The array was arranged as rows of modules as illustrated in the accompanying schematic. The array layout is designed to maximize system size while allowing only minimal losses due to shading and ensuring the system is aesthetically pleasing and well-integrated with the barn.

This 12,420W (12.42 kW) grid-connected solar electric system was installed as fifty-four (54) SunPower 230 W solar modules oriented South on three (3) Direct Power and Water adjustable-tilt top-of-pole mounts at the north end of the pond covering the deck. The poles hold the modules arranged as six (6) rows of three (3) modules in landscape, and each have typical dimensions ranging from 15.4 ft x 9.7 ft x 14.3 ft (width x height x depth) at 25° tilt to 15.4 ft x 15.9 ft x 9.1 ft (width x height x depth) at 55° tilt, as illustrated in the accompanying schematic diagram. The array layout is designed to maximize system size while allowing only minimal losses due to shading and ensuring the system is aesthetically pleasing and well-integrated with the property.

The system is configured electrically as five (5) DC circuits (strings) of eight (8) series connected modules through two (2) DC disconnect switches to one (1) Sunpower/SMA 6000m, 6.0kW inverter and one (1) SunPower/SMA 4000m, 4.0kW inverter (roof-mounted system), and then six (6) DC circuits (strings) of nine (9) series connected modules through three (3) DC disconnect switches to three (3) SMA 4000m, 4.0kW inverters (ground-mounted system). These inverters provide grid-synchronous AC output and interface to the electric utility through a dedicated circuit breaker or direct tap in the Customer's main service panel, as existing infrastructure allows. System power production (kW) and energy production (kWh) monitoring is provided by a Datalogger and web-based portal, as well as by a digital display on the inverters and an electromechanical meter.

As designed, this system should generate 26,800 kWh per year, for an average of 73 kWh/day, where daily energy production is both weather and seasonally dependent. This energy production is equivalent to 78% of the customer's expected future electrical usage for the Bed & Breakfast with the installation of a geothermal DX heating and cooling system and air-air heat pump system, and corresponds to a CO2 (greenhouse gas) emissions savings of 34,840 lb per year.