green homes for india enabling india get 50% of its power from … · 2017-03-06 · green homes...

Green Homes for Indiaenabling India get 50% of its power from solar by 2030

Ashok Jhunjhunwala, IIT Madras [email protected]

with Prabhjot Kaur, Krishna Vasudevan, Lakshmi Narasamma, Devendra Jalihal, M Kumaravel and Bhaskar Ramamurthi

mailto:[email protected]

Power for Indian Homes: A dilemma

• 50 million homes not connected to grid

• About 100 million homes have load-shedding between 2 hours a day to 12 hours a day

• 50% of Indian homes can not afford power even at subsidized rate of ₹5 per unit

– At this tariff all DISCOMS lose money

Living Science Platform 2September 16

In first week of December 2015

• When whole of IITM had no power for 75 hours• Even 1 MW solar plant at IITM failed to provide any power

– There was one home which continued to have lights and fans and cell-phone / lap-top charger• 125W solar panel + 0.5 kWh of solar battery• Two tube-lights were used regularly + bulb and fan occasionally + laptop charged /

discharged fully 15 times + cell phone charging• Fails to add up

– Solar DC Inverterless• Full DC wiring, all Loads DC, solar and battery connected on DC line, input grid power

converted to DC


But AC Power won 125 years ago!

• In an AC Vs DC power-line debate between Tesla (for AC) and Thomas Edison (for DC) in 1880’s– AC won decisively due to transformer’s ability to step-up and step-down voltages

easily• And reduce line losses

• AC dominated ever-since– Transmission lines became all AC– Homes and offices were wired on AC line (230V AC in India)– All appliances became AC– All R&D focused on AC

• R&D on DC virtually stopped


Decentralised Solar Power at Homes

• Solar PV gives DC Power– But load is AC

– Needs a DC-AC converter

• Now if we add a battery– Battery stores only DC

• Require an AC-DC converter for charging

• Require a DC-AC converter during discharging

• For low power, each converter can have 10 to 15% loss– Solar with battery may have up to 45% loss

+ battery loss


AC Load

DC-AC

Battery

AC-DC DC-AC

Grid

Solar DC

And it gets Worse

• As one realises that home-loads have been slowly moving towards DC

• All Electronics devices work on low-voltage DC– TV (LED/LCD), laptops. Cell-phones, speaker-phones, tablets, speakers

• AC to DC conversion has losses from 20% to 50% in each device

• Even the refrigerators, air-conditioners, washing machine in future will be BLDC motors

• Use of DC-powered and energy-efficient devices– Consumption down by 50%


Fans AC fan BLDC fan

At full Speed 72W 30W

At speed 1 60W 9W

Lighting CFL Tube light LED tube

At Max. Intensity 36W 15W

At Lowest Intensity NA 4W

Volume prices similar for fans

LED tube life much longer (DC powering enhances reliability)

Are we ready to take a leap?

• And move towards a DC power-line at homes– and at offices, commercial complexes and industry

• Need to Standardise Voltages– For low power 48V DC is ideal

• Safe– Used by a telephone line, all telecom, within vehicles and power over Ethernet for

decades

– Can be easily used to power LEDs and electronics

• 24V DC would quadruple line-losses; 12V DC would increase it by 16 times

– For higher power, one can look at 380V DC


Smart Homes should have Solar-DC

• DC Micro-grid connecting– Solar Panel

– Battery

– DC Appliances

• Highly efficient usage of Power– Low-power from grid alone converted from AC-

DC (Designed to have minimal losses)

• But design non-trivial– Solar MPPT voltage varies

– Battery needs independent charge voltage

– Load is at some fixed voltage

– DC-DC converters will add similar losses


AC-DC

battery

Loadgrid

Solar

48VDC

48VDC

48VDC

IITM designed Solar-DC Inverterless


125W to 500W 48V DC (and possibly 150W uninterrupted AC) Power with BLE prepaid recharge

125W panels• Upto 500W possible

230V AC

Special 1 kWh VRLA battery with 1600 cycles for 50% DoD• Up to 5 kWh possible

Designed as an expandable product, still keeping losses low

Monitored using Bluetooth

And worked with start-ups to build Appliances

Living Science Platform 10September 16 10

LED Bulb• 5W instead of 30W bulb

BLDC Fan• 30W instead of 72W AC fan• 9W at lowest speed Remote Control for Fan &

Tube light• ON/OFF and for dimming

Cell phone Charger/Socket• DC charger with USB port

LED Tube light• 15W - dimmable to 4W, instead of 36W

fluorescent tube

Cost: ₹20000 for 125W SP + 1 kWh Battery+ appliances

Energy-efficient DC appliances being expanded


DC-powered 19/24” Colour TV• Consumes 30W along

with set-top box at 48V DC

DC Desert Cooler• Consumes 80W

instead of 180W AC cooler

Refrigerator and Stove• Still experimental

DC Mixer• Consumes 150W,

whereas AC Mixers consume 350W

Deployment in Rajasthan

• Electrified 4000 off-grid homes in Jodhpur and Jaisalmer districts of Rajasthan

– Tough terrain, no road connectivity, sandstorms, lack of local resources

• 7500 homes in Assam being taken up in hills

– More in other states: Orissa, Jharkhand


Deployments in deserts of Rajasthan

Living Science PlatformSeptember 16 13

4000 scattered Homes provide excellent field conditions

• The system design was new and complex with each sub-system being justoptimal in terms of size and costs

• The stated aim to reduce cost and size by reducing losses

• Is this reduction in losses realised inpractice (it did in lab prototypes) indifferent field conditions

• Is system functioning well atthese locations?

• are sub-systems behaving right?• Is solar power getting wasted?• Is battery remaining healthy?• Can performance be further improved?

– Cost / performance needs to be examined


Need to monitor each system

• For the purpose of diagnostics, performance evaluation and management– Measure solar-power, battery (in / out)

power and Load power every few minutes

– Building such diagnostics in Inverterless was trivial

• But requires connectivity to the cloud

• Needs to be Low-cost as compared to Inverterless– Operations costs needs to be low

• Inverterless costs ₹3000; wireless modem will cost similar + monthly cost of usage– Need a different approach

• Most homes have a phone• Use Blue-tooth to connect

– Use phone to relay to cloud


Over Internet

16

Measurements from a home in Bhom Ji ka Gaon, Jodhpur from 9am to 5pm

• Understanding use of solar Power and losses: performance evaluation• Is customer using more than what solar power provides?

• Is she using less? Is power being wasted?• In Grid-connected system (no reverse feeding for small system), grid-usage can be optimized

to use all of solar power

Solar

Battery

Load

Living Science Platform

-75

-55

-35

-15

5

25

45

65

85

105

125

Jul-

01

00:

00

1:5

5

3:5

0

5:4

5

7:4

0

9:3

5

11:3

0

13:2

5

15:2

0

17:1

5

19:1

0

21:0

5

23:0

0

Jul-

02

00:

55

2:5

0

4:4

5

6:4

0

8:3

5

10:3

0

12:2

5

14:2

0

16:1

5

18:1

0

20:0

5

22:0

0

23:5

5

Day and Time

Battery power (W) Load power (W) Solar power (W)

Monitoring Usage

September 16

Monitoring by Customer

• Using Mobile App on customer phone

– Tracks power usage throughout day

– Tracks power generated and stored

– Tracks State of Charge (SoC) of battery

• For grid connected system

– Power availability

– Help her plan conserve if required• Dim lights / fans

– Helps user alter usage to avoid waste


Villagers thrilled

• “Apne Vidyarthiyon ko ghar ka kaam dene lagahu. Khush hu ki is baar garmiyon mein bhi

bachhe mann laga kar padhai karenge.” [now Igive my students home-work. Happythat even in summer they will now beable to study]

- Masterji

• “Sab ko utshah se apne ghar ka Solar systemdikhata hu ji, hamare ghar mein bhi pankha,

light aur remote hai” [show my solarsystem to everyone at home. Have fan,light and remote]

- Dunga Ram• feedback: https://youtu.be/NF6EgdRsBXk


https://youtu.be/NF6EgdRsBXk

Motivation for going Solar Inverterless

• It is a Solar + power back-up, butfar more efficient

– as 100 Watts DC• Can support 3 lights + 2 fans + cell-

phone charging

• Or 3 lights + 1 fan + TV (24” LED/LCD) +cell-phone charging

– Solar Panel and Batteries have to beappropriately sized• Devices can be added as required


Small Home AC Home DC Home

Energy/ day kWh

Cost per day ₹

Energy / day kWh

Cost per day ₹

AC Grid + 0 LS 3.27 16.3 1.29 6.45

AC +Battery + Solar + 4h LS 3.75 28.9 1.35 7.3

off-grid + Battery + Solar 4.9 50.6 1.33 12.6

Small AC / DC Home Power Costs

Device Numbersdeployed

Operationhrs/ day

Tubelights 2 6

Fans 2 12

Bulbs 2 10

Phones 1 4

TV 1 10

Cost / day includes depreciation and interest for solar panel and battery assuming grid costs of ₹5 per unit

Living Science Platform 20

Off-grid home power-costs with solar-DC (₹12.6 per day) less than the cost of on-grid AC homes with no power-cuts (₹16.3 per day)

September 16

Solar-DC: Equally important for grid-connected homes

• Solar-DC Inverterless + DC power line + DC appliances: huge cost savings– Draws less from grid: reduces power-bill

• Provides back-up power: frees homes from load-shedding, grid-fault

• 500W solar power (50 sqft) with DC appliances can take care of most essential loads in middle class homes

• Except washing machines, air-conditioners

– 240M homes with 500W solar panel produces closeto total domestic consumption in India in a year• 240Mx0.5 kWx1550 solar hrs/year = 190,000 GWh /year


DC Power-line can play equally important role

• In Offices, Commercial Complexes, high-rise buildings, hospitals and educational institutes

– In driving decentralised solar to power them

– Most loads have anyway become DC

• Not just in powering Appliances

– But also in air-conditioning, cooling systems, lifts and pumps


Apartments Offices Hospitals Educational InstitutesCommercial Complex

APPLICATIONS:

DC LED bulbs

Desktop DC PCs

Exhaust fans

230 V AC 48 V DC

Grid

Rooftop Solar

Display ScreensLaptops

Sensors

VAVs

DC mobile charging socket

Battery backup (optional)

INVERTERLESS2400

Inverter

DC LED Tube Lights

Routers

Battery is

Charged /

discharged

using DC Power

DC Power line would avoid AC-

DC-AC conversions at each

applianceSaves 15-20% energy

Most of today’s appliances

and equipments (LED lights,

laptops, PCs, Displays, sensors,

fans etc ) use only

DC PowerSaves 15-50% of

energy

VFDs

Can eliminate DG

23Living Science PlatformSeptember 16

Energy Efficient Smart Green Buildings

• Roof-top Solar Powered: natural supply demand match for cooling

• Use DC Power line to power its lights, fans and electronic load /sensors

• Air-conditioning Distribution Systems (like AHU and VAVs) – Best driven by DC Motors (BLDC or SR motors)

or Variable Frequency Drives (VFDs)using DC power

• Water pumps, Lifts would benefit fromDC motors or VFDs– Should be able to pump most water

when sun is there


To Sum Up: Decentralized Solar Focus

• Green DC-powered Homes driven by Solar-DC– Power at affordable rates even during load-shedding

• Lower / Middle Income homes can not afford power even at subsidised rates

– will draw less from grid: reduces losses for DISCOM

• Green DC-powered Buildings with roof-top Solar– can reduce power-consumption by 30% or more

• India must aim to get 50% of Power produced using Solar by 2030– At the same time India can get 100% vehicles to be electric by 2030

India becomes the most Sustainable and Green Nation

25September 16 Living Science Platform

green homes for india enabling india get 50% of its power from … · 2017-03-06 · green homes...

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