AT&T Off Grid - Reducing
Generator Fuel Costs
off grid solar site upgrade to
supercapacitors reduces costs
optimizes fuel consumption
Lead Acid Batteries vs. Supercapacitors
Reduce maintenance and replacement
The Supercapacitors will provide more than 25 years of service. We would need
to replace the lead acid batterieis in 3 years with 2 cycles per day. The bonus
was that the cost of the supercaps was lower than the lead acid batteries.
Kyle Locke, Project Manager, AT&T Mobility
AT&T ANTELOPECELL SITE
28.4 KWh of Storage
DC POWER PLANT
16kW Vertiv Rectifiers
7 Solar Controllers
15 KW SOLAR, 4.000 GALLONS OF PROPANE
- 28.4 KWh of Storage
- 4,000 gallons of propane
Years of Service
Supercapacitors vs. Lead Acid Batteries
Years of Service - Supercapacitors
27.4
Years of Service - Lead Acid Batteries
2.04
Off grid facilities that depend on renewable energy (solar, wind, etc.) require storage to maintain a power supply through the night or times when the renewable source is not producing. For critical infrastructure, fossil fuel generators will also be a component of the facility.
If the renewable energy source and storage combination is not large enough to supply 100% of the power, then the fossil fuel generation becomes can be called upon to supplement. In either case the combination of renewable and storage will require cycling (charging and discharging) the energy storage system. Every energy storage system is limited by the number of times it can cycle.
Lead acid batteries have very limited cycling capabilities. In this case the lead acid batteries planned for the site were rated for 1,500 cycles. The supercapacitor modules are rated for 50,000 cycles. This particuar site cycles the energy storage system two times per day. Charged by the solar panels during the day and then by the generator at about 1:00 AM for the second charge in 24 hours. In our calculations we handicap the supercapacitors to 20,000 cycles. The end result is that the supercapacitors last more than 27 years while the lead acid batteries require replacement every 2 years.