Solar lanterns are now coming with rechargeable batteries and LEDs for improved brightness

Based on simple technology, solar lanterns are becoming more innovative, safe, rugged and user specific

By Richa Chakravarty

Thursday, July 03, 2014:According to Tarun Kapoor, joint secretary, Ministry of New and Renewable Energy (MNRE), the demand for solar lanterns has increased manifold over the years. The chronic and severe power crisis in the country and the fact that vast areas are still without grid connectivity are the most important factors driving people to scout for alternative energy sources to light up their homes and business establishments. However, different kinds of solar off-grid products, which are technologically more advanced, are posing a threat to the basic solar lanterns, compelling manufacturers to introduce innovative versions with new features. Hence, consumers now have a wide variety of solar lanterns in the market to choose from.

What’s new in the market?

A solar lantern consists of a PV module, a lamp, battery and electronics, all placed in a suitable housing, made of metal, plastic or fibre glass. The battery is charged by electricity generated through the PV module. These lanterns are portable and suitable for indoor or outdoor lighting. Hence, these are made compact, lightweight and rugged, for use under the toughest conditions.

Solar lanterns with long life batteries: Solar lanterns are fitted with VRLA batteries, which neither have a long life nor any protection from short circuits. Most of the solar lanterns are equipped with ‘double A’ batteries, which have less than 50 life cycles and are not rechargeable. Whereas, other parts of the solar lantern, particularly the panels, have a life of 20 years. Hence, manufacturers are now making lanterns with long-life batteries.

“Users usually don’t want to invest Rs 1000-2000 on a solar lantern that will last for just two years. Hence, we are working on a new lantern that would run for 20 years. The product is still under development, based on research,” informs Raghunandan, vice president, engineering, Kotak Urja Pvt Ltd. The company’s Sparkler Deluxe solar lantern offers a working life of approximately 50,000 hours.

Su-Kam, on the other hand, has advanced solar lanterns that overcome the limitations and problems of less battery life—consumers have an advanced range of lighting products to choose from. Its solar lantern has a microcontroller-based design and is equipped with Li-ion rechargeable batteries rather than conventional lead acid batteries. The company had introduced its Sparkle and Sunglow solar lanterns in 2013 and 2014, respectively, and has recently added a new range called Sunbeam to its portfolio. “Our solar home lighting products are compact, portable and easily mountable, and they come with an easy-to-install kit. They provide a backup of 32 hours,” shares Dhananjay Sharma, AVP, solar business, Su-Kam Power Systems.

In order to provide long hours of uninterrupted lighting, Oorja Solar offers a solar lantern with a phenomenal backup of up to 30 hours on a single charge. This lantern is excellent for cloudy regions and places where there is less sunshine.

Rugged, compact and yet with impressive aesthetics: Since this product category is specific to the rural population, most manufacturers are working on making solar lanterns more reliable, rugged and appealing. The lantern body is being made with acrylonitrile butadiene styrene (ABS) plastic, which comes with two core 14-strand cables. Hence, even if the lantern is dropped, it does not break and neither do its mechanical parts get damaged. “The trend is moving towards smaller lantern cabinets as people want solutions that are compact and handy. Hence, we have designed a product that is compact, handy and reliable,” informs Rishabh Sood, director, operations, Regnant Lighting.

Solar LED lanterns: Manufacturers are also moving away from CFL bulbs and using bright white LEDs that provide better brightness. While a standard CFL has a life of about 6000 hours and spreads the light upwards as well, the more advanced LED lights run for almost 50,000 hours. Regnant has introduced a solar lantern under its Ujjwal family of products in December 2013, which uses high-brightness SMD LEDs (a total of 30 LEDs of 0.06 W each), with a total power consumption of a little below 2 W. Also, the lanterns have high, medium and low light options, regulated CC/CV charging and regulated mobile charging with a 5-in-1 mobile charging lead.

Oorja Solar’s solar lantern consists of 80 LEDs. Kotak Urja’s Jumbo solar LED lantern has long lamp life, and 360° lighting with uniform illumination, which is anti-glare and hence soothing to the eyes.

L&T has developed a unique solar lantern called Diva. When fully charged, it is capable of emitting uninterrupted light for up to 10 hours at maximum brightness and for as long as 40 hours in night mode. It has an in-built dimming feature, which intelligently monitors brightness control and provides a wide range of light outputs to suit outdoor and indoor needs at various times of the day. It also has mobile charging and a smart 4-LED battery status indicator.

Multi-purpose solar lanterns: Users today are looking for solar lanterns that offer more than just light. Keeping this requirement in mind, manufacturers are designing products that can be used for varied purposes. Gautam Solar Pvt Ltd (formerly Gautam Polymers) has designed a multi-purpose solar lantern for use in both urban and rural areas. With 3W LED lights, a 3W solar panel and 6V-4.5Ah battery, it requires four to five hours of charging to run for eight hours on ‘single brightness’, six hours on medium brightness and four hours on full brightness. This solar lantern can be used as a torch, a hanging light, a study lamp, can be slung over the shoulder and can charge mobile phones too.

Hybrid solar lanterns: Based on hybrid technology, these lanterns can be charged with both solar and mains power, and provide emergency backup via their built-in lithium-ion battery. The lanterns offer both low light and bright light, depending on the requirement of the user. Oorja Solar’s HT06 solar lanterns can be charged using a solar panel as well as the electricity from the mains. They come with twin flourescent lamps, which are good for studying as the light is soft, compared to LEDs which are very bright for the eyes.

Lanterns with safety features: Today, most solar lanterns have safety features like a shock-proof and vibration-proof body. Su-Kam’s solar lantern provides protection from short circuits. Kotak Urja’s Sparkler Deluxe also has protection against shock. Regnant Ujjwal solar lanterns have safety features that include intelligent low discharge and overcharge protection.

Introduced in December 2013, Panasonic’s BG-BL03 solar LED lantern has IP34 rated protection against dust and water. This lantern has been designed to emit 360 degree light with a 3.5 W solar panel. The lantern’s built-in battery can be fully charged in approximately six hours under fine weather conditions.

Choices in solar panels: Two types of solar PV panels can be used to power solar lanterns—crystalline and amorphous (thin film). Crystalline panels take up less area than the amorphous panel for the same amount of energy produced. However, crystalline panels do not perform satisfactorily under cloudy or not-so-bright conditions, when compared to amorphous panels. The choice of the panel depends on the location of the lantern as well. Typical ratings of the solar PV panel range between 8 Wp and 10 Wp.

Says Rishabh Sood, “Regnant-Ujjwal solar lanterns come with a 6V 5W solar panel that charges the battery better, as compared to the 6V 3W panel usually being provided by other players.”

How to choose the right product

When opting for a solar lantern, it is important that buyers understand what purpose they need it for. In rural areas where it acts as the only source of light, the buyer should look for lanterns that give 360 degree illumination so that the light spreads equally. If the lantern is to be used in urban areas where solar lanterns are treated as emergency lights, this aspect is not of great importance.

Advises Dhananjay Sharma, “Customers should consider their location, power availability and usage requirements before buying a solar lantern. They should also calculate the hours they expect the lantern to function.”

If the lantern is to be used for studying, the lights should be soft yellow and not bright white. Suggests Rishabh Sood, “It is important for the buyer to check whether the lantern has regulated CC/CV charging. The glare to the eye from the LEDs must be kept in mind, as it may cause great discomfort if used for long hours.”

A solar lantern which is energy efficient and is of good quality will prove to be cost effective. Buyers should check the battery back up and the quality of the control unit, and these should have a higher life cycle. A good quality, long-lasting battery will extend the life of the solar lantern and also help in curbing the health hazards caused by poor quality lead acid batteries.

It is also important to check the warranty period of the lantern. It is always advisable to buy from only authorised dealers of branded inverter and power product companies.

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