Rooftop solar units and mini power grids are beginning to grab the attention of house owners.

Unlike coal vs. natural gas, paper vs. plastic, or elevators vs. escalators, once you’ve decided to opt for a domestic energy system that reduces grid dependence, your dilemma becomes a win-win situation. In most cases, these alternative systems, which are quickly becoming game-changers in domestic energy, will help save costs while reducing environmental footprints.

What is sparking a shift away from the normal solar set-up, and driving elimination of grid dependence during the day, are the new plug-and-play models, which come with quirky innovations such as trapping heat or more efficient inverters.

Bangalore-based Orb Energy, for instance, offers urban domestic energy solutions that produce alternating current (AC), ramping up efficiency by nearly 50 per cent. “It’s simple. What most people don’t realise is that solar panels produce direct current, which is why you need an inverter between. With common inverters, however, you can lose almost 50 per cent of your power, which removes the cost savings the solar panel gives you in the first place,” said Damian Miller, Chief Executive Officer, Orb Energy. While Orb does have do-it-yourself kits for rural homes, its Solectric AC system for urban homes uses a unique inverter that increases efficiency.

Orb Energy’s systems range from 100 watts to 1KW, with prices ranging similarly from Rs. 60,000 up to Rs. 3 lakh. “If you compare it against diesel, which is around Rs. 15 per KWh, the Solectric system with batteries will come to about Rs. 13. The average payback period is anywhere between five and seven years. What increasingly we see commercial users doing, however, is plugging in the system during the daytime. This displaces the grid and lets you function at Rs. 8 per KWh,” said Miller.

At the other end of the spectrum is another Bangalore-based player, perhaps better known for its green residential projects but also making breakthroughs in domestic energy systems. BCIL’s ZED Group offers ZedSun solutions for larger domestic homes, which are essentially mid-range micro-grids that can cut a user’s energy demand by up to 70 per cent. “We prefer to think of some of the solutions we do as supplementing the grid with smart power packs. The rooftop set-up is planned in such a way that it reduces the heat signature of the building and helps in conserving energy. The installation offers grid freedom through the day, while the battery installation ensures about two to six hours of energy drawn from storage,” said Chandrashekar Hariharan, Executive Chairman, BCIL ZED Home.

“Our major objective is to replace UPS and gensets used as back-up power in small offices and larger homes. We start from 2 .5 KW solutions that can be amortised in less than five years with the system generating energy for 25 years, with guarantees that cover maintenance at period stops through the tenure of the installation,” added Hariharan.

The company also offers cloud computing tools that let consumers check power consumption every hour. According to the company’s research, the use of a ZedSun solar unit works out to under Rs. 5 per unit, including interest on purchase cost. And it promises a 200 per cent return on the investment in ten years.

For consumers, the process looks like it can only get simpler — with standalone rooftop solar power plants and solar inverters becoming increasingly popular.

“I must say it has become very easy. My family decided to go for a rooftop power plant from Swelect Energy. We conducted a quick feasibility study, and then installed a plant of 1 KW capacity and 10 solar panels,” said P. Ganesh, a resident of Adyar, Chennai.

The installation was designed to exclude energy-guzzlers such as air conditioners, refrigerators and geysers. Ganesh said the capital cost was around Rs. 2.5 lakh, inclusive of the subsidy.

“Power disruptions are a thing of the past as I now have three energy sources – the plant, the batteries and the electrical line. While this is a very typical set-up, which doesn’t include some of the more creative power designs, it helps me save around two units a day,” he said.

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