Green Gadgets: Basil’s low cost inverterless AC/DC solar power system

Basil Energetic’s breakthrough solar power hybrid system switches seamlessly between AC & DC, has less load current, and delivers energy at half the cost and space!

Basil Energetic’s breakthrough solar power hybrid system switches seamlessly between AC & DC, has less load current, and delivers energy at half the cost and space!

After negotiating the impossible Chennai traffic and getting lost, I finally arrive at the Rain Centre. This rather nondescript building is at the forefront of rain water harvesting in Chennai. And now, it is the venue of a breakthrough experiment in alternative energy.

Dr. Ram and Ram, as I call them, have just put together an integrated workable solar energy system, working on both DC and AC current, that homes and industries can use, at half the cost of existing technologies. Dr. Ramarathnam created the system after more than a few years of R & D, while the other Ram, S. Ramakrishnan, enabled the system to be installed in the Rain Centre. The company, Basil Energetic Pvt. Ltd., has been recently formed to take the invention to market.

The new rooftop solar system

As the country is attending another round of talks at COP 19, the Minister of Environment and Forests in an interview said, “I don’t think I would be wrong in saying that India has taken far more initiatives than many, and are internally very proud of these. We are by no means a naysayer. We only object to any prescriptive policies that are dictated to us by others, who are actually not doing anything to combat climate change. We have a great deal to show. We have initiatives to enhance building efficiency and we are doing studies on the issue of black carbon.” It is innovation, the likes of which Dr R and his team  have delivered, that are the real solutions that are changing the scenario, amid the many COP meetings that have happened over the years.

After meeting Dr. Ramarathnam and looking at his invention, I can say that at this point of time there is no building anywhere in this world that has the kind of system that harnesses, harvests sun energy to give light and cooling, saves expenses, provides efficient appliances cost effectively. At a household level, the application of this innovation has critical use across a wide variety of users.

In a lay person’s language what this does is use a compressed and space efficient solar panel that continuously absorbs the solar light and converts it into energy. The electrical energy goes directly into appliances such as the ceiling  fan, an air conditioner and a refrigerator, as well as other appliances such as computers. This set up can be used in a household as well as for industrial use.

How it works

Existing rooftop solar systems

Consist of Solar Panel, Battery with Charge Controller and Inverter
Uses existing inefficient appliances – Air Conditioner, Fridge, Fan, Light

Inside homes, it is difficult to handle larger motor driven loads like AC and fridge due to a high in rush starting current and the need for a higher power rated panel, battery and inverter. Due to the above the size and cost of the system goes up and hence has not been deployed in a wide manner. The roof top area required is high and hence deployment in apartments becomes an issue. Battery maintenance and replacement costs are also a deterrent.

The new system

• No inverter. Hybrid application which can work on AC Mains or DC from Solar panels.
• Soft starting of motor loads – no in rush current
• A Central grid controller does the following:
(i)Continuously monitors the power availability and load requirements
(ii) Switches the appliances from DC to AC or vice versa
(iii) Ensures maximum utilisation of solar power at all times
(iv) When generation is more than the load requirement, the excess energy can be fed back to the grid, if allowed, like in a smartgrid.

• All the above result in the drastic reduction of the panel power rating, which comes down to a third of the conventional system
• The roof top area is also reduced correspondingly. Hence applicable in multi-storeyed apartments easily.
• The overall cost of the new system, including the appliances is less than that of the existing system even after excluding the cost of the appliances
• When there is no sun shine and solar energy production, the system runs from AC Mains. Even in this case, the energy consumption is cut by half
• The power factor presented to the grid is near unity at all times.
• There is no need to store the energy in batteries. However this can be done if back up power is needed. Even here the KWHr rating of the battery is drastically reduced, resulting in smaller floor space.

Model Installation in Chennai

Load consists of One 1 Ton Air conditioner, One 330 Litre Refrigerator, Three 1,200 mm Ceiling Fans and Nine LED lamps.
A conventional system needs a 5 KW solar panel, battery with charger and a 6 KVA inverter with a roof top area of around 40 sq.m. The new system uses only a 1.44 KW solar panel, no battery and inverter and the roof top area used is only 11 sq.m.
The cost of the new system including the hybrid appliances is only about half of the present system without accompanying appliances.

Model costs

600W – One 300 litre fridge, Three 1200mm Ceiling Fans & Nine LED lights. – Rs 2 Lakhs

1440 W – One 1 Ton Air Con, One 300 litre fridge, Four Ceiling Fans and 10 LED lights – Rs 4 Lakhs

1920 W – One 1.5 Ton AC, One 300 Litre Fridge, 12 LED lights and Four 1200 mm ceiling fans – Rs 5 Lakhs

Possible Application Areas

The new system can be deployed in homes, offices, shops, etc without any change in the wiring. It is ideal in remote areas where electricity is not available but sunshine is. Additional new energy sources like Roof Top Micro Wind, PICO Hydel, Biomass/Biogas generation systems can be easily added to the smart micro grid. Depending on the site conditions and availability of the renewable sources we can install a local smart micro grid for a hamlet, village or a set of homes.

Even as the technology is travelling to urban centres, from health establishments to businesses, buildings and IT complexes, it is the 400 million people in India still do not have access to electricity and use kerosene for lighting that Basil wants to take the technology out to.

You can find out more about this Rooftop Solar system with hybrid appliances by writing to:


The Greenprint Your Home series by The Alternative brings together news, views, analysis, expert opinion, photospreads, product reviews, DIYs and much more to help you go green with your dwelling. This series is in collaboration with ZED Habitats, a pioneering green developer in India.

Pushpanath 'Push' Krishnamurthy has three decades of experience at the leading edge of development work across three continents. At Oxfam he has led pioneering campaigns such as Make Trade Fair and the Climate Change Hearings. With a background in development studies and agricultural science, Push has grassroots experience from regions as diverse as East Asia, Southern Africa, the Balkans and the ... more


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Pushpanath 'Push' Krishnamurthy has three decades of experience at the leading edge of development work across three continents. At Oxfam he has led pioneering campaigns such as Make Trade Fair and the Climate Change Hearings. With a background in development studies and agricultural science, Push has grassroots experience from regions as diverse as East Asia, Southern Africa, the Balkans and the ... more

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  • Interested in solar

    This looks very appealing. Could you please provide a website and other contact information to help those who would be interested in having a solar powered system like this and what they would need to do to get something like this done (maybe get the whole thing constructed and installed by you or get consultancy from you or…)? Also, if you do this for others, would it be only in Chennai or in other cities in South India as well?

    • Aarti Mohan, The Alternative

      Article updated with this information and some cost breakup as well. It is now being sent from Chennai to other places. Thanks, Aarti.

  • Venkata Chamala

    hi guys dont get too excited about this. i am pleased to see some developments in this sector, the two Rams, definitely need to appreciated. but when i see the cost economics, i cant help feeling let down.

    please see ned cap figures for solar systems

    6. If 1 KW Solar Roof Top System is installed

    a) Estimated cost of system – Rs.1,10,000

    b) MNRE subsidy – Rs. 30,000

    c) State Subsidy – Rs. 20,000

    d) Net cost of the system – Rs. 60,000

    e) Expected generation per day – 4 units

    f) Expected generation per month – 120 units

    7. The net energy consumed – 120 units

    ( 240-120)

    8. The Energy charges payable – Rs.332.00

    9. Net Savings per month – Rs.741.20

    10. Net savings per year – Rs.8,894.40 ps

    11. Pay back period – 6.74 years

    12. Life of equipment – 25 years


    1.Considering the consumer is also utilizes the Air conditioner of 2500 Watt load

    for 4 hours a day, the total energy consumption would be 17.9 units per day

    and the consumption for month would be 537 units.

    2. Energy charges in normal course per month – Rs.3,317

    3. Estimated cost of 3 KW Solar Roof Top Systems – Rs,3.00 lakhs

    4. MNRE subsidy (upto 1 KW) – Rs.30,000

    5. State subsidy (upto 3 KV) – Rs.60,000

    6. Net system cost – Rs.2.10 lakhs

    7. Expected energy per month – 360 units

    8. Net Energy – 177 units

    9. Energy charges for Net Energy – Rs.537.20

    10. Net savings per month – Rs.2,779.86

    11. Net savings per year – Rs.33,358.32

    12. Payback period – 6.3 years

    so the author should explain, how, this model is cost effective, and can i suggest, please just dont publish for the sake of publishing something.

  • Ram Ramarathnam

    Hi Venkata

    I am the Dr Ram referred to in the article. Please note that the panel rating needed to run the appliances (one 1 Ton AC, one 330 Litre Refrigerator, Two 1200mm Ceiling Fans and 9 LED lights). The key differentiator in this solution is the deployment of Super Efficient Appliances like AC, Fridge, Lights & Fans. Contrary to what you had assumed in your calculations, our AC requires far less power. To start with the 1 Ton AC needs only 850W and after about 20 minutes of cooling the power demand comes down to 300 – 350W only. Similarly for fans and fridge, which takes only 25 & 70 W power.

    The existing, market available AC may take 2500W. But you cannot run it with a 3 KW panel as the starting current required for this appliance is about 5 – 6 times the full load current. Hence with existing AC & Fridge loads, the PV panel, Battery and Inverter have to be over rated at least by 2 – 3 times. Our system introduces soft starting for motorised loads and hence does not need this over rating.

    The loads, which are installed in the model house in Chennai, would normally require a 5 KW panel. Whereas we are doing it with a 1.44 KW panel. Unless one needs back up power, it is better to do away with batteries. I suggest you rework the economics with the revised power rating of old and the new systems and the new one will be economical even without subsidies. Also please remember that when you run from the mains the power/energy consumed will come down by half.

    The following table gives the power rating of the different appliances – old & new:

    Appliance Power (W) Starting current (x Full load current)
    Old New Old New
    1 Ton AC 1400 300 ~ 840 5- 6 times 1
    1.5 Ton AC 1800 450 ~ 1200 5 – 6 times 1
    330 Litre Fridge 200 30 – 70 5 – 6 times 1
    1200mm Fan 55 25 2 times 1

    The power values given for old appliances are for BEE 5 Star rated appliances. These will be higher when they are not star rated. The new appliances comes under SEEP (Super Energy Efficient Products)

    In fact due to the existing inefficient appliances and the huge starting current loads, existing systems normally do not address heavy motor loads. We have overcome exactly this. I hope I have clarified the doubts. You and others can contact me for more details.

    We are installing more systems in Chennai now but will soon expand to the rest of TN and Kerala. After that we will enter AP/Telengana and Karnataka, as we are looking for a suitable channel partner there. Progressively we will expand to the whole of the country.


      sir, we are interested in this article.
      can we represent you in salem region as distributors?
      pl send details.

    • Ram Ramarathnam

      Hi Sampath

      Please contact us and we can definitely consider you as dealer for Salem. You can contact Ramalingam at + 91 7299 2268/69 who is handling the marketing. One more thing – we are participating in an exhibition in Coimbatore where we are exhibiting a mini truck fitted with solar panels, one AC, one Fridge, 2 Fans and 4 LED Tube Lights. We will be there from Feb 13 – 16 and we can meet there. This exhibition is called “RENERGY Coimbatore 2015” which is a sub event of ELEKROTEC 2015 organised by CODISSIA>

  • Ram Krishnan

    I wish to thank Pushpanath for a well written article. There was another article in THE HINDU newspaper. That has a picture. See this link.