Solar module is the centre of solar technology. And although there has been a considerable technological evolution in solar module development for more efficient solar energy generation, consistent growth is needed for successful transition of green energy source into mainstream energy. To win over the fossil fuel and to stay constantly viable as an energy source, the world needs to make sure that solar energy generation is consistently increased while need for space is reduced. Better cell usage, advancing junction properties, screen printing, doping are few of the many ways how energy yield maximization is assured through solar modules. Continuous advancement in cell & module technology is the only way to keep solar energy relevant in today’s fast changing world to match energy generation and usage pattern.
One of the most researched option of maximizing energy yield through modules is considered to be increasing the number of busbar. The PV industry has undertaken extensive research into busbar technology to reduce electrical & shading loss, thereby maximizing energy output from a cell. This has gained more importance today with the advent of high efficiency technologies like PERC, heterojunction etc. For the uninitiated, the metal stripes that run from the front to the rear of each solar cell is known as busbar. It collects the electrons generated from the solar cell at the presence of sunlight. And research shows that present solar module efficiency also depends on the number of busbars on the cells in the module. Less than 5 years ago solar modules used to have 2 busbars, then came 3, 4 and today the transition is towards 5 busbars. Multi busbar (MBB) technology (12 or more busbars made of Copper) and busbarless (back contact) technology look promising keeping the future in mind. Let us have a look at the effect of having 5 busbars as compared to 3 or 4.
More busbars = better electron collection
Electrons generated in a solar cell by impact of photons have a mean lifetime. When there are more busbars (meaning more contact points with fingers), more electrons get into the electrical conduction system of the cell before being captured by ‘holes’. This reduces electrical loss in a cell.
Thinner busbars = lesser shading loss
As number of busbars are increasing, their thickness is decreasing thereby reducing the shading loss due to presence of busbars on the cell surface. Thinner busbars also mean less silver requirement; so this has a price implication on modules as well.
More Busbar = Lower Degradation
There is a certain level of degradation of solar cells when they are soldered into the modules. Research shows that 3 and 4 busbar module stringing process records a certain level of efficiency loss in modules. However, shorter gaps between basbars (which 5 busbar modules offer) reduces the residual stress approximately up to 10%. As the level of degradation is lower in 5 busbar modules they can offer better durability and a longer lifespan with increased energy generation advantage.
Therefore, it is easy to glean from the context that increasing the number of busbar stripes on the cells will definitely increase the energy collection capability of the module, thus breaking the barriers of the known energy generation limits.
And since the world is moving towards accepting and upholding solar energy as mainstream energy, making solar module more and more efficient is of extreme importance. And increasing busbar numbers will significantly enhance the numbers of contact points within a solar cell, making the solar module highly efficient in generating green energy. Additionally, with better and faster energy collection from the cells, the issue of hotspot formation (which reduces energy generation capacity) will also be diminished in 5 busbar modules, solving another problem with ease.
Only Innovation Can Pave the Path to Future
Solar has obviously given us an edge to fight the debilitating energy crisis. If we look a little far back, we will see that in 1977, solar panels cost $77 per watt p, and current cost $0.33-$0.36 cents/per Watt p identifies more than 2 orders of magnitude fall in prices.
A decade ago, Solar was considered experimental and was a niche industry in the huge sector of energy generation. And in 2016, power generation from renewable sources in the world has surpassed coal based energy generation.
Today, Solar PV panels have a huge demand, global capacity additions nearly reached 100 GW in 2017. These patterns lead to continuous fall of solar panels prices, and battery storage systems are also getting cheaper, promising of storing more stable and clean solar power.
Countries are investing more in renewable energy ($286 billion in 2016) than conventional fossil fuel ($130 billion in 2016). All of this points towards global acceptance of solar energy and highlights the efforts to make it a mainstream energy source.
However, it is important for us to evolve the technology quickly for mass adoption. Dominant countries like China, US, Japan are focusing on innovation by investing huge amounts of money in R&D, adopting technology transition, and creating competition between solar manufacturers to develop better products.
As a progressive country focused towards solarisation, India needs to follow in these footsteps as well. And speeding up or adopting the 5 busbar transition in the country seems to be the right step towards the brighter change the country has envisioned.
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