Off-Grid Commercial Photovoltaic System
Chris Lanane, Air Monitoring Specialist
Great Basin Unified Air Pollution Control District
“Apex Solar installed a 5.28KW solar power station in a very remote location for the District. They did a great job on the installation, were courteous to District staff that were onsite, and professional in their demeanor. Their knowledge of the equipment and its operation was impressive. They were very willing to take time to explain to the staff how the system was to be installed and why and were very patient in training District staff in the operation and maintenance of the system. We, at the District, are very pleased with their work and would hire them again for future solar power equipment installations.”
Description of Site:
The site is located at Mono Lake, California. This is an extremely remote and harsh environment. Summer temperatures extend into the high 80s and in the winter the temperatures can go into the low 20s and winds can gust to 100 + mph. These winds blow an acidic combination of sand and lake salts onto the site. Accessing the site required the use of ATVs and tracked vehicles due to the sand dunes and the soft blowing sand conditions. The existing solar system that was in place at the site showed signs of extensive abrasion on the modules from blowing sand. All electrical equipment had fine dust intrusion and was failing due to the harsh conditions.
Customizing the System:
Apex Solar was to assist with engineering and provide complete installation and setup of the 5.28 KW solar power station. The air monitoring equipment required 120 volt AC power 24 hours per day, 365 days per year. Carmanah was the supplier for all the equipment installed and had developed a relationship with the Great Basin Unified Air Pollution Control District. Apex Solar worked closely with Carmanah’s engineers to develop a system that would withstand the high winds and the harsh environment.
The solar array was to be situated on a level area of the sand dunes, 500 yards from Mono Lake’s water’s edge. The site conditions required a number of considerations. First, the modules had to be placed high enough above the sand dunes so that the gusty winds wouldn’t sandblast the modules. Second, the location that the solar rack was to be placed was on very fine sand and rack pull out due to loads on the module was a serious concern.
A third consideration was that due to the temperatures extremes, the equipment and the batteries needed to be placed in a stable environment and kept as protected as possible from the blowing dust. The ideal enclosure for the batteries and the equipment was Zomeworks’s Cool Cell. The cool cell uses a passively cooled enclosure that circulates water to keep the interior at a stable temperature. Apex Solar installed three (3) of the cool cell enclosures, two (2) large battery enclosures (4’ x 4’ x 6’) and an equipment enclosure (2’ x 2’ x 6’).
The solar array was mounted on a framework of 1 ½” schedule 40 steel pipe. The pipe was driven by jack hammer into the sand at a depth of 5-6’. To ensure that the leg mounts would not be pulled out during high winds, Apex Solar installed earth anchors at numerous locations that were connected to the rack with steel cables.
32 Sharp 165 modules
24 GNB Absolyte IIP batteries
2 Morningstar TS-60 charge controllers
Exeltech XP 1100 inverter
Cool Cells From Zomeworks for Battery and Equipment enclosures
Results of Installation:
This system was installed in November 2007 and has been operating maintenance free since installation.