Last month the Indian government announced it had  reached the psychologically important milestone of 100 gigawatts in nationwide renewable energy  capacity. India, eager to develop its renewable infrastructure, may yet reach its ambitious target  of 175 gigawatts on-stream in the year 2022, and 450 GW overall renewable energy  capacity by the close of this decade.

To do that, Indians will need to make solar panels. Lots of them. Vikram Solar is one of a few big players in the field vying for a slice of this lucrative growing market.   And Vikram recently expanded its  own capacity by a not-insignificant 1.3GW through the opening of its new 130,000  square feet plant in Oragadam, Tamil Nadu. So let’s see what goes down inside. Solar panels, also called solar modules, are  made up of a number of individual solar cells.

These cells can trace their origins back to simple silica sand, from which silicon is extracted.   Silicon is the second-most-abundant element  found in the earth’s crust by the way. So we’re not likely to run out any time soon.

Cooked at 2,000 degrees Celsius in a furnace along  with a source of carbon, the raw element is then cooled to create metallurgical grade silicon.  This is usually liquified again in order to   remove remaining impurities.

It’s then blended  with a pinch of boron and a dash of phosphorus, molded into ingots then sliced into  tiny wafers less than 0.2mm thick. These wafers are then coated with silicon nitride  and roughed up a bit to create texture and reduce reflectivity – any light that bounces off a solar panel is wasted, of course.

A silver paste is then applied to the front and rear surface and, pretty much, that’s your solar cell. At Vikram Solar’s new Tamil Nadu facility,  these incoming cells are visually inspected to find any obvious cracks or breakages.

Cracks in the solar cells render them useless for large modular applications like solar panels. But more  often than not, smaller sections of solar cell can be cut away and used for smaller, less intensive  off-grid applications, like solar powered toys.

After this manual visual inspection,  the first of several tests under blasts of artificial sunlight, to  check they work, is undertaken. Then a hydraulic conveyor system  introduces a layer of EVA – that stands for Ethylene-vinyl acetate – to a flat  pane of tempered glass.

This EVA layer serves as an adhesive to hold fast the rows of solar cells that are automatically laid on the pane in a careful tile pattern, by this six-axis  robot arm that can move 12 cells at once.

The cells are connected to each other, and ultimately the grid, via a criss-cross pattern of narrow metal ‘fingers’ and fatter ‘busbars’  . These carry electrons generated from the   activated cells to the tab wires and beyond,  to whatever the panel will ultimately power.

Engineers looking to maximize efficiency of solar cells have debated whether its better having more busbars – conventional wisdom says 5 is a good  upper limit – because resistance is lowered, although the additional hardware inevitably shades parts of the solar cell.

More fingers and busbars can also mitigate the  risk of micro cracks appearing in the cell, or at least prevent cracks  spreading too far across the cell. Once all the cells are in place, another  layer of EVA is laid over the panel and an additional backsheet is added to  encapsulate the cells and internal wiring.

The next stage is called  ‘pre-lamination electroluminescence’.   Exploiting one curious property of photovoltaic cells – that they light up whenever a current is passed through them – inspectors can look  even closer for microcracks that might render the final panel inefficient or at worse useless.

All they need to do is identify the dark spots. These microcracks, incidentally, can  creep in at any stage of the process. Silicon wafers are notoriously brittle, and  mishaps during the manufacturing or transportation phase are common.

Wild fluctuations in ambient  temperature can also cause irreversible damage. After this pre-lamination electroluminescence  phase comes – you guessed it – lamination. An industrial laminator applies heat and vacuum  pressure to the ‘sandwich’ of glass, EVA, solar cells and wires, bonding everything together in a taut, weatherproof panel.

Following this stage, circuit ribbons are attached to the edges,  and an aluminum frame placed around the edge. This aluminum frame offers the panel sturdiness,  which helps prevent nasty cracks.

These frames also make the panels much easier to handle and  store, as well as offering some resistance to the day-to-day mechanical loads the panel will be subjected to, like heavy snow or gale-force winds.

Another electroluminescence test follows, and the installation of a so-called ‘junction box’ on the backside of  the module using strong silicone adhesive. This junction box serves not only as the collector  of electricity, but its diodes ensure power only ever flows in one direction.

This is important,  because solar panels by their very nature generate differing and unpredictable amounts  of electricity throughout their working lives. Final testing looks for weaknesses in the panel’s weatherproofing.

Next, the completed panel is subjected to a final blast of artificial  sunlight. And now our panel is ready to ship. Vikram Solar’s shiny new Tamil Nadu facility is part of a wider drive within India to achieve what prime minister Narendra Modi has  called his ‘Atmanirbhar Bharat’ initiative.

This translates, pretty much,  to ‘self-reliant India’,  the idea being to wean the subcontinent off  of its dependence on foreign expertise and expensive imports. The new plant is all set up  to embrace emerging technologies, for instance using Artificial Intelligence algorithms to spot  microcracks early in the manufacturing process.

As Vikram Solar’s managing director Gyanesh Chaudhary puts it. ‘This is an extension of our  endeavor to provide high quality, reliable, technologically superior products  and timely delivery to our customers.

It will further contribute as an R&D  platform for next-gen module technology’. Talk about sunny optimism. What do you think? Is solar still exciting? Let us know in the comments,   and don’t forget to subscribe for more  utterly illuminating tech content.