George "The IceMan"

George “The IceMan”

Introduction

There was a buzz around Aizawl with projects getting approved and lenders giving away  loans and making payments, I was still searching for my Solar order, with the help of my supplier I had managed to get demo kits, which included an Inverter, a Battery Pack and Panels which I could put up on the Dodge Ram I had rented from a car rental agency in Aizawl.  When I had landed here I had no doubts in my mind what I had to accomplish now, the two months spent with this family had been worthwhile.

I slipped out of my makeshift room, the garage, and went looking for my truck, it was a  Dodge RAM  V8 4x4, probably the only one of its kind in the whole town of Aizawl.  It consisted of a beautifully built cabin for the driver and  a  driven caravan at the back, I knew this, because I had ridden one of these in the two years in USA.  Thoughts of Allison filtered through my head, we had driven through a similar looking forest in a Red Dodge Ram and she had lowered the window on the passenger side, the drift of cool breeze had sifted through the cabin, her hair flew across her eyes, while I was in the driver seat and enjoying the power transfer of the machine.

Suddenly the wind speed had picked up and it looked like the makings of a tornado brewing, with dark clouds and torrents of rain, we had parked at a nearby hotel, it was an old place and they had a bomb shelter, we had gone down the ladder into the shelter nervously, there was another couple with a young daughter there, the place was small and had needed a lantern to light up the place.  The electricity had obviously tripped because of the storm and we sat and waited.

“Joe, do you think we are going to be camping here for long ?” she had asked me, clinging to my arm, I could feel her warm breathe on my forearm and her soft body clutching to mine.  I wasn’t thinking too much about our predicament, just enjoying this feel, this moment when I had her with me with no interruptions.  I would die for moments like these, warm intimacy and sensual touch.  Those days I was an intern with a news agency and it took all of me to make ends meet, most of the money I earned got spent on Allison and the clothes I bought to impress her.

Suddenly, the wind screeched like a banshee, it must have been clocking 200kmph, and the latch of the overhead jam of the bomb shelter gave way and the door got blown away along with the guy who had been holding on to it and I was scared.

                     Take a Minute, a Deep Breath, and Lets Plunge Right Into It.

George “The Iceman”
                                    – Great Designs Have History To Emulate

Having done a basic study of Inverters in the last post, and visited Huka Sumi’s farm, I had hit upon an idea of developing a prototype for Solar Tractors, it made very good sense for farms to use Sun Power for their energy requirements.  I met Kali Awomi, another of Vibeikho’s friends, she had just come back from college having finished her Mechanical and Manufacturing Engineering.

What follows was an hour of design conversation that got my mind going, and then conclusions to finish over a cup of tea :

“Do you think we are on the right track ?” I asked her after an hour.
“I think so, what we need is a prototype of a tractor that will run on solar panels, that ain’t so easy, but we will do it.”
“How many HP is a Mahindra Tractor?”
“I suppose that would be 15HP?
“Let me design the specs,though the roof top may be a  little low on space.”
“You design, leave the rest to me.”

I spent the rest of the day, working out effective Solar Specifications  for the Solar Tractor :

Design Specifications

No of Cylinder	1
Capacity, cc	863
Engine Rated RPM	2300
Transmission Type	Sliding Mesh
No of Gears	6F+3R
Brake Type	Dry
Main Clutch Type & Size	Single
Lift capacity at Hitch, KG	778
Steering Type	Mechanical
Fuel Tank Capacity, LIT	24
Wheel Base, MM	1490
Tyre Size, Front/Rear	5.20 - 14/8.00 – 18

Solar Design for George “The Iceman”

Total HP for  Tractor  = 15
that equals Kw = 12000w x 2 hrs a day x 7 Days a Week / 7 Days in a Week
 =12000WHrs

Total W = 12000W
Total WHrs/day = 24000WHrs/day

Battery Design
Step I
Find the invertor efficiency which in this case is 0.9
24000 /0.9Inv Eff = 26666 Wh/day

Step II
Calculate the ampere-hour/day, remember  watts = Volts x Amps
26666 wh/day / 48 DC system Volts =555 avg    AH/day

Step III
Use the above figure to find the System AH which will generate the battery specs
555 x 1.11 battery temp multiplier x 3days    autonomy /0.5 DOD = 3700 total system AH

Step IV
3700 total AH / 450 Ah individual battery    capacity = 9 parallel battery strings
48 V system voltage / 12v 2V monoblock battery voltage = 4 batteries in series
9 parallel strings x 4 batteries in series = 36 batteries

Array Design

Step I
Get that formula :

24000 Wh daily load / 4.6 peak sun hours /0.8 battery eff /0.88 temp losses / 0.9 shading coefficient / 0.85 system derate = 9687W peak array

Step II
Find the no. of modules needed :

9687/250 W STC@12V = 39 modules needed
48 V Nominal array Voltage / 12 V nominal module voltage = 4 modules/string, 10 strings total 

This done, I thought it over as I sat sitting in the Sailovi’s Garage, do I write specs for the inverter as well in this post and then reconsidered.
Tada’ till tomorrow !!

                                    Hey ! You, Outta my Car, I got a Solar Tractor Now.