Batteries: (72) Trojan deep-cycle IND29-4V batteries
Inverters: (9) SMA Sunny Island 5048 inverters
Solar modules: (650) 100W PV thin film modules
Charge Controller: (9) Sunny Mini Central 7000HV charge controllers
Racking: Space frame structure
Spice Village, founded in 1992, is a 56-cottage resort on the border of the Periyar Tiger Reserve in the Kerala province of Southern India and is one of the largest solar-powered, off-grid resorts in the world. Described as “a tribute to ancient ways of life” where “hewn stone replaces shag carpets” and “birdsong takes the place of television,” the resort provides comfort for modern travelers while giving them a chance to enjoy a simple “back-to-nature” experience.
Considering the recent trends and growing demand of the global traveler for eco-friendly destinations and properties, the hospitality industry is under pressure to “go green” to ensure the lowest possible environmental impact from tourism. For this reason, the management at Spice Village decided to use energy efficient measures and solar power to make Spice Village a low carbon emissions resort.
In late 2011, Spice Village hired solar company TeamSustain to design and install an off-grid photovoltaic system for the resort. TeamSustain is a leading clean, green technology solutions provider based in Cochin, India. The company offers cost-effective logistics and infrastructure solutions for sustainable resource utilization to markets around the world.
Until June 2012, the resort was connected to the electrical grid but it also relied on a diesel generator for backup power due to poor grid quality. The generator ran eight hours a day to supply power to the cottages and resort buildings. Not only was it noisy, but it was expensive to run and time consuming to maintain since fuel had to be purchased and transported from a long distance away. The existing system consisted of two generators with capacities of 125kVA and 200kVA which produced almost 61,695 kWh a year.
By analyzing a compilation of energy audit data and identifying how to reduce the electrical load without compromising the use of necessary facilities or comforts, TeamSustain was able to improve the resort’s energy efficiency, reducing the daily consumption from 750kWh to 200kWh. Incandescent and florescent lighting was replaced with LED lighting, desktop computers were replaced with laptop computers, unnecessary items such as hair dryers and kettles were removed from all guest rooms, and electrical appliances including ceiling fans, TVs and refrigerators were upgraded to more efficient models.
Once the energy efficiency upgrades were made, TeamSustain designed a 65kW battery-based PV system for Spice Village. The system was designed to support the full load of the resort after implementing the energy efficiency measures identified in the energy audit. With the new PV system, the resort will generate enough solar electricity to meet 100% of its power needs.
The PV system consists of 650, 100W thin film modules wired in 108 strings of six modules per string for a total system size of 65kW. They are mounted in a fixed array with a 16 degree tilt. Due to the high vegetation of the area and adhering to a mandate that no trees could be cut, TeamSustain used a space frame structure to raise the solar array 33 feet above the ground to avoid shading. A space frame structure is a truss-like, lightweight rigid structure designed using interlocking struts in a geometric pattern, and is ideal to span large areas with few interior support requirements. This elevated design also maximizes irradiance and utilizes the area underneath for the tennis and basketball courts.
Thin film PV modules were chosen due to the typical climatic conditions at Spice Village of overcast skies and high temperatures. Amorphous silicon (A-si) modules are expected to provide a 15% higher yield than conventional crystalline technologies in this environment.
TeamSustain designed an AC-coupled micro-grid PV system using nine SMA Sunny Island 5048 inverters in clusters of three for a total capacity of 45kW. The inverters convert the DC electricity generated by the PV modules to AC electricity. The SMA inverters are highly efficient, easy to configure, and their intelligent battery management system helps ensure maximum battery life.
Nine Sunny Mini Central 7000HV inverters were used to allow more modules to be connected in series than is possible with common inverters due to their higher DC input voltage and maximum power point tracking range. This reduces cabling costs on the DC side and simplifies the installation. Their performance range permits the installation of large PV systems made up of distributed string inverters, which allows for detailed system monitoring.
The energy produced by the thin film modules is stored in 72 Trojan deep-cycle flooded IND29-4V Industrial batteries. Trojan batteries were chosen by Team Sustain due to their reputation for high quality and reliability, the fact that they were made in the USA and because the size of the Industrial batteries met the specifications of the project design. Flooded deep-cycle batteries were chosen for the project over valve-regulated lead-acid (VRLA) batteries because of their affordability and durability. Since the resort has a maintenance program in place, watering the batteries periodically with distilled water will not be an issue. Trojan’s Industrial batteries have wide plates which allow for more electrolyte to be stored at the top of the plates, allowing for longer intervals between watering.
Each battery has a 1,409 Amp hour capacity at C10. The Trojan 72 IND29-4V batteries are wired in six strings of 12 batteries, with two strings paralleled per each inverter cluster for a 48V DC output with a total capacity of 8,454 Ah at C10. Trojan’s deep-cycle flooded battery technology used requires simple maintenance to ensure maximum battery life. Adding distilled water to the individual cells regularly assures maximum battery life. The battery bank was designed for 50 percent depth of discharge with two days of autonomy.
Trojan’s Industrial line of flooded deep-cycle batteries is designed for 1,500 cycles at 80 percent depth of discharge and is specifically engineered to withstand the rigorous conditions of renewable energy applications including extreme temperatures, remote locations and the intermittent nature of solar power generation. These batteries are designed to be cycled regularly and are engineered to perform optimally under conditions where the batteries are in a partial state of charge (not fully charged or discharged every day); a common occurrence in renewable energy applications due to the varying levels of irradiance, temperature, and available sun hours.
The anticipated payback time for the PV system is five years. Spice Village will receive a 30% subsidy from the Indian government on capital costs as part of the Jawaharlal Nehru National Solar Mission (JNNSM) Rooftop Plant Program. This project is also eligible to earn carbon credits since there is an expected carbon reduction of 256 tons of CO2. Overall, Spice Village expects to save nearly $45,000 per year by switching to solar energy.
For more information contact:
Trojan Battery Company www.trojanbatteryre.com
Spice Village: www.cghearth.com/spice-village