04 August 2016 16:23:44 IST

Next time you build a house…

…make sure it’s all-DC, solar-powered. Savings on the power bill will make you smile

If something has increased 15 times in three years, it is safe to conclude that there is something happening there.

I have authoritative data that worldwide investments in ‘off-grid systems’ — systems that do not draw electricity from the state power grid lines — has gone up 15-fold in three years, to $276 million in 2015. This is a paradigm shift. This means we are witnessing the head of a mega-trend towards what wisdom always dictated — produce energy where it is to be consumed.

Now, these off-grid systems — such as homes that produce their own energy — could be powered by any device — say, a small bio-gas plant, a diesel-driven generator box, a micro wind turbine on the roof, or, a solar power plant. However, by and large, solar is the cheapest and the most sought-after, and presumably has consumed a disproportionately large part of the $276-million investments.

The AC-DC debate

This brings us to the point that this column has been actively advocating. As those who have been reading this column would know, the advent of solar also implies a come-back of direct current. (Here is a little background: back towards the end of the 19{+t}{+h} century, two big names in science – Thomas Edison and Nikola Tesla – fought for adoption of direct current and alternating current, respectively. Edison owned a company that later became General Electric; Tesla worked for George Westinghouse’s company, which is today Westinghouse. Ultimately, Tesla won, and today we have alternating current powering our cities.)

Today, with solar rooftop solar is gaining ground rapidly, especially in the ‘industrial sector’ with large-roofed factories going in for widespread rooftop power generation. The question, in the last three-four years, has been: why not have TVs, fridges, fans, mixers and grinders work on the direct current that rooftop solar panels produce? Today, the rooftop current is converted into AC to run these appliances.

It is worse when it comes to electronic gadgets such as computers. They have to be re-converted to DC for that purpose. Each conversion loses energy, and you also have to pay the cost of the equipment that does the conversion. The answer to why homes didn’t have all-DC appliances was mainly that there were technical challenges. Also, standards for DC equipment were not in place and, either due to that or other reasons, appliance manufacturers did not come up quickly enough with DC products.

Pilot projects

Now, this is all changing. Welcome to the era of solar DC homes.

To show what is happening, I take you to Rajasthan, to a village called Bhomji ka Gaon, a village that was not even connected to the rest of the world by a proper road, what to speak of electricity. In December 2015, the Government of India launched a scheme to power 4,000 homes with solar+DC appliances, and Bhomji ka Gaon was where it all started.

Each home is being provided with a 125 W solar panel, which is very small, a battery, a DC-fan, a DC-tubelight, a DC-bulb and a socket-cum-mobile charger. Imagine the relief of having a ceiling fan above your head in a Rajasthan summer!

What if a slightly larger solar panel is put up, and the output is shared by a cluster of homes, rather than each home having its own small solar power source? That would be a micro-grid, (or a mini-grid, if it is larger). That’s what they did in a village called Tirmal in Odisha. They put up a solar panel and connected 27 homes and a school to it. Then, another project came up in the same village. Three solar-plus micro grid systems were set up to connect three clusters of 30 homes each. A similar project has been executed in the Nilgiris, in a village called Kundithal.

These pilot projects have shown encouraging results. Now is the time for large-scale adoption. For that to happen, the government needs to prescribe standards that manufacturers could follow.

Standards and start-ups

Fortunately, there is some activity happening in this area. The IEEE Low-Voltage dc Forum in India proposed 48-V dc power as a standard for home power involving low-power appliances. The Bureau of Indian Standards is now working on such standards and is veering toward the 48-V dc standard for homes. UK-based standards body International Electrotechnical Commission has set up a subgroup to examine DC power standards for homes and other usage.

Once the standards are out, manufacturers of electricity-powered household appliances will, for sure, bring out DC-based products. Already, the DC-run air-conditioners are gaining acceptance.

Alongside, another interesting sub-trend is visible. Start-ups are coming forward to build solar homes. In Chennai, a company called Basil Energetics is making a pitch like this: For a fixed sum of money we will put up a solar plant on your roof and replace most of your appliances to DC-based ones that can run on the power the rooftop plant is producing. The price is graded, depending on the level of use.

In Hyderabad, a company called Cygni is making a similar offer.

You see the coming together of various elements of the ecosystem? Solar rooftop plants, standards for appliances, manufacturers coming out with products that can run directly on power produced by the solar plant and companies that will do the installation jobs.

So, next time you build a house, be smart enough to make sure it is all-DC, solar-powered. The electricity bill savings will make your wallet happy.