The document discusses strategies for making rural base stations in India more profitable by reducing energy costs. It finds that: 1) Energy prices fluctuate widely in India due to power shortages, making diesel generators and batteries expensive to operate. 2) Modeling shows that using solar panels and proper battery selection can reduce daily energy costs by one-third, and combining both can reduce costs by another third. 3) For new sites, reducing power consumption, eliminating air conditioning, using battery chillers, and right-sized DC generators can optimize costs. For existing sites, adding solar panels and revitalizing batteries through proper charging can balance currents and lower operational expenditures.

1. Powering the Remote
Rural Base Station
Can it make Indian telcos profitable?
ashok Jhunjhunwala, IITM ashok@tenet.res.in
N. Sriram, IITM
04-04-2012
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2. India’s 15% average
power deficit is deceiving
As evident from the fluctuating prices
at Power Markets
• Day variation of Rs 2000 to 4500 per
MWh
• Prices vary from Rs 2000 to 12000 per
MWh in one week
• Huge power shortage during peak hours
• rural / remote areas have huge cuts
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3. ‹#›
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4. Some statistics from
ACME
• 1.5 to 3% energy in developed countries consumed by telecom
operators and data centers
• Energy consumed by wireless operator doubles every 3 -5 years
• Cooling infrastructure consumes > 50%
• DG operation average 6 hours per day
1 unit BTS consumption: 1.5 units consumed
• India grid availability varies between states by AC, SMPS loss, PIU loss, battery leakage
• Battery maintenance neglected
• 15% batteries are non-functional
• 1800 MHz TRX consume more power
• Passive site equipment dominates CAPEX
• $25K for active (electronics) and $62.5K for passive
• Tower, shelter, Power system, Battery (VLRA),
AC unit, Earthing
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5. Energy Storage
• Batteries are expensive proposition for back-up
• Lead acid battery: 1500 cycles if operated between 60 to 100% capacity
• 1 kWh back-up will cost Rs 14/ kWh assuming single charge / discharge
per day
• Assuming Rs 6000 per kWh battery and 10% interest rate
• LiFePo battery: 5000 cycles if operated between 10% to 90% capacity
• 1 kWh back-up will cost Rs 16 per kWh assuming single charge per day
• Assuming Rs 25000 per kWh battery and 10% interest
Lead acid battery
Battery cost (per kWh) Rs. 6,000.00 Battery cost (to deliver 1kWh) Rs. 15,000.00
discharge 40% depreciation (years) 4.11
Number of cycles 1500 Storage cost per unit -Rs. 14.09
interest rate 10%
cycles used per day 1
Losses 10%
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6. Diesel generator
• Diesel generator generates 3 kWh of power per litre of diesel
• But this is true only if generator is working at 80% load
• Efficiency drops significantly at lower loads
• Increasing costs of diesel power
• DC diesel generator does
not have this problem
• Fuel consumption is almost
linear with load
• For charging battery and driving
BTS, why not use DC generator?
• Why convert to ac at all?
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7. Sun shines brightly
over India
• India can certainly use solar energy, as capital goods prices fall
• Solar photo-voltaic provides DC power for about six hours a day
• Rs 60 per W capital cost: with 10% interest and payback in 20 years, amounts to Rs 7
per year (not computing costs of land)
• Total Cost of Ownership gives a little over Rs 4.35 / kWh assuming 10% losses
assuming no land cost
• Installation costs may add another 10% to costs
• As opposed to Rs 3 to 7 per kWh for grid power
Solar PV power price computation
PV cost per kWp 60000 sun-hours per day 6
interest rate % 10% sun-days / year 300
depreciation (yrs) 20 total units gen per year 1800
yearly payment Rs. -7,047.58 Losses 10%
price per unit Rs. 4.35
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8. Strategy
Grid: Rs 5 per unit
Solar: Rs 5 per unit
• What are the sources? Battery back-up: Rs 15 per unit
• at what costs and available when? Diesel Generator: Rs 15 per unit
• What are the Loads? BTS
Air-conditioner
• Can we reduce some loads? Battery-cooling
Battery-charging
• In existing installations
• In new installations, for example
• reduction of BS power: 147W -> 130W -> 120 W Diet-BTS
• Reducing / eliminating Air-conditioner requirement
• Use of battery chiller
• Will require one to optimize usage of sources to
minimize total cost of operation
• OPEX + CAPEX converted into EMI
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9. IITM Simulator
• Designed to compute
• Battery, PV current, Total Load
current as a function of ambient
temperature at different point of time
• When do DG and grid turn on and off?
• What happens to battery charging / discharging?
• Assumptions in simulations
• Grid Availability: 4 h
• Diesel Generator Sizes: 15 kVA
• Load Power factor: 0.8
• Diesel Cost per liter: 45 Rs
• BTS Load: 0.8kW
• BTS Cooling Load: 1.8kW
• Battery Cooling Load: 0.5kW
• Total Peak Load excluding Battery Charging: 3.1kW at 48V
• PV and battery CAPEX built into energy costs as EMI
• DG CAPEX and fuel-pilferage not included
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10. 15kVA Generator, No PV, NO
Battery, 4 hours grid
availability
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11. 600Ah, 48V Lead Acid Linear Battery
Charging
Battery,
Battery, 4 Hours grid Model
availability, 15kVA DG
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Green Telecom & IT workshop, Bangalore Rs 23 per unit

12. 600Ah, 48V Lead Acid
Non-linear
Battery,
Battery, 4 Hours grid Battery
Charging Model
availability, 15kVA DG
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13. 150Ah, 48V Lithium
batteries,
Polymer batteries, 4 Hours
grid availability, 15kVA DG
Linear Battery Charging Model
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14. 600Ah, 48V Lead Acid Non-linear
Battery + 5kW PV + 15kVA Battery
Charging Model
DG + 4 Hours grid availability
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Green Telecom & IT workshop, Bangalore Rs 15 per unit

15. 150Ah, 48V Lithium Polymer
battery + 5kW PV +4 Hours
grid availability+15kVa DG
Linear Battery Charging Model
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Green Telecom & IT workshop, Bangalore Rs 14 per unit

16. Simulation
Conclusions
• Use of proper
battery reduces
daily energy OPEX
by one-third
• Use of PV panel
further reduces
daily energy OPEX
by one third
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17. But one can optimize much more
700Ah, 48V Lead Acid Battery + 7kW PV
+ 15kVA DG + 4 Hours grid availability
Non-linear
Battery
Charging Model
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18. How does one go
forward?
• For new sites
• Reduce power consumption in BS and associated electronics
• Eliminate air-conditioner (make systems workable at 500c ambient)
• Place Battery in chiller
• Use dc diesel generator of right sizing -- critical
• But more important (for existing and new sites)
• Add solar panels
• Revitalize batteries – choose Lead Acid or Lithium Polymer
• Balance current load and power-sources
• Optimize when to use what based on simulations
• Have powerful remote management
• With the aim of using diesel generator only as an exception
• Key is to reduce total cost of operation of towers
• Taking CAPEX / OPEX
• Much can be done today
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