A SHLS is typically a Battery powered system that is charged using a Solar Panel. The energy stored in the battery is then used to illuminate one/more rooms of your home or shop or classroom. These systems can also offer mobile phone charging and the ability to charge the battery using AC wall socket.
Uses of a Solar Home Lighting System
India of the 21st century, sadly, has not been able to satisfy basic power requirement for all of its citizens. Till that happens, a SHLS can provide a good alternative to satisfying needs of homes/shops so that businesses can run & kids can study well past sunset. A SHLS can be used in places that either do not have reliable 24 hours grid electricity OR no grid electricity at all. It can also be useful for people on the move like soldiers, campers, and small vendors. Furthermore, with mobile phones becoming a basic necessity for all; a SHLS can provide that essential ability to charge a mobile device even when there's no access to AC power.
Types of Solar Home Lighting Systems
SHLSs can come in all shapes and sizes. These range from the very small Solar Key Chains giving a couple of hours of light to the off-grid Solar AC Inverter which enables you to run all your AC Loads like Lights, TV, Fans, Mixer, etc for several hours all together.
Following are common types of Solar Home Lighting Systems:
This is the lowest in the food chain of solar lights and falls under the category of a novelty item. It has a very small solar panel, a tiny battery, and a very low power LED light, all of which can fit on a key-chain. It can come handy as a low power torch and charges on ambient light. These, however, do not last very long as the battery usually is of fairly inferior quality to keep the cost low.
A solar lamp typically offers a small LED light (0.2 to 1W) powered by a re-chargeable cell (NiCd, NiMH, or LiIon/LiPolymer/LiFePO4). A small Solar Panel (usually about 0.5W or less) is attached directly to the body of the lamp that enables you to charge the light during day time. Such a lamp provides 3-5 hours of light and can sometimes also have a mode that lets you adjust the brightness to extend the battery life. The illumination offered by such a lamp is usually sufficient for tasks like studying/cooking but will not illuminate the entire room. These usually do not offer mobile charging as the battery is of a limited capacity. A good brand will use a Lithium Ion (or similar) cell that can last for more than 1000 charge cycles. One disadvantage however can be the general availability of an appropriate Li Ion cell and the cost of replacing such a cell.
A solar lantern looks like a kerosene lantern and provides uniform illumination all around. These are usually made of several (20-40 nos) low power LEDs, and are typically powered using 6V Sealed Maintenance Free (SMF) Lead Acid Batteries. The Lead Acid battery will have a shorter life (around 1 year), but can be easily replaced. Good brands like Luminous/Excide/Amaron generally do not make 6V batteries, so one is at the mercy of cheap Chinese brands. Few solar lanterns can also offer you mobile charging, but it's usually not sufficient for charging smart phones that consume more power. Solar Panels for these lights are usually separate, and come with a long wire so that you can place the panel in the Sun and the lantern indoors. This is important because heat tends to reduce the life of a battery, and you can get better performance form your solar light by keeping it away from heat and sun.
Such a system has a bigger Lead Acid battery (12V 7.2Ah) commonly found in small UPS systems and easily available in local battery stores for about Rs.700. This system supports one/more CFL lights OR one/more LED lights with optional mobile charging. CFL systems, which you might have seen with some vegetable vendors, require more power and therefore give lesser backup. In CFL systems, the battery also wears out sooner. LED systems are better because of the long life of LED bulbs and they consume less than half the power of CFLs. Like Solar Lanterns, these systems have a separate Solar Panel usually 10 to 15W in power that charges the battery in 8-10 hours. Some systems will also provide AC charging. Typical backup for CFL systems is about 4 hours for 2 11W CFL lamps, while it can be 10-12 hours for 2 LED bulbs of 5W. Green Pyramid Solar is working on special techniques that extends total hours even further.
This is the big daddy of SHLSs and runs your normal 230V AC loads like fans, mixers, CFL/LED Lights. These come in 2 flavours: Solar Off-Grid Inverter, and Solar Hybrid Inverter. A Solar Off-Grid inverter is suitable for homes with no access to grid electricity. These have Pure Sine Wave/Modified Sine Wave AC Inverters running off Inverter Batteries (100Ah - 200Ah) which are charged using Solar Panels. A Hybrid Inverter runs off the Battery as long it's fully charged. When the voltage of the battery falls under a specific level, the solar panel charges the batteries and the load switches to the grid. Hybrid Inverters help you reduce electricity bill providing you power backup at the same time when grid is not available. In these systems Solar Panels tend to be bigger, in the 100W to 200W range, and need to be properly installed to get most out of the system. These also require a higher upfront cost. Panels last more than 25 years but batteries have to be replaced 3-6 years, which should be factored into the cost of the overall system.
Lighting based on Solar Power is now available in several form factors. You can select the correct system based on your specific needs and price range. Several of these are also available online on websites like ebay.in, and amazon.in, which lets you compare prices and read customer feedback. Green Pyramid Solar has also introduced a range of these lights which we would love for you to check out!
Author's Note: If you have any further questions, feel free to add a comment to the Blog, and I will try my best answering those in a timely manner.