- Solar Lantern Definition: A solar lantern is a portable solar electric system used for temporary lighting both indoors and outdoors.
- Main Components: It includes an electric lamp, a battery, and an electronic control circuit, with the solar PV module connected separately.
- Functionality: The solar PV module charges the battery, which powers the lamp, providing efficient lighting.
- Different Models: Solar lanterns come in various configurations based on lamp type, battery capacity, and PV module rating.
- LED Benefits: LED-based solar lanterns are energy-efficient, consuming less power and requiring smaller batteries.
A solar lantern is a well-known example of a portable stand-alone solar electric system. It has all the necessary components in one casing, except for the solar PV module. The lantern mainly includes an electric lamp, a battery, and an electronic control circuit. The solar PV module is separate and needs to be connected to the battery terminals for charging. Solar lanterns are used for both indoor and outdoor temporary lighting. The casing can be made of metal, plastic, or fiberglass and houses the battery, charging circuit, and control circuit. A lamp holder is mounted at the center, holding either a fluorescent lamp CFL or LED lamp. The lamp is covered with transparent fiberglass. The top cover, made of the same material as the casing, includes a hanger. There are plug points and indicators for charging and discharging on the casing.
To charge the solar lantern, connect the solar PV module placed in sunlight to the plug point on the casing. Different models of solar lanterns exist, but typically, the battery capacity is 12V, 7Ah. The CFL lamp used is usually either 5W or 7W. The solar PV module for charging ranges from 8 Watts peak to 14 Watts peak.
A table showing different configuration of solar lantern as per MNRE specifications is given below
| Model | Lamp (CFL) | Battery | PV Module |
| I-A | 5 W | 12 V, 7 Ah at 20oC | 8 to 99 Watts (Peak) |
| I-B | 5 W | 12 V, 7 Ah at 20oC | 8 to 99 Watts (Peak) |
| II-A | 7 W | 12 V, 7 Ah at 20oC | 8 to 99 Watts (Peak) |
| II-B | 7 W | 12 V, 7 Ah at 20oC | 8 to 99 Watts (Peak) |
The lumen output is generally in the range of 230 ± 5 % for 7 W CFL.
The Components of Solar Lantern
Solar Module or PV Module
The solar PV module for charging a solar lantern is usually rated at 8, 10, or 12 Watts peak (Wp). It is often placed on the rooftop at an angle that receives the most sunlight for the longest time. Lanterns kept indoors or elsewhere are connected to the solar PV module using a wire socket. Some users prefer not to install the solar module on the rooftop and instead place a portable module in sunlight daily.
Battery
Normally we use maintenance free sealed dry type lead acid battery of tabular shaped with 12 V, 7 Ah capacity for solar lantern.
Inverter
A CFL lamp requires an inverter to convert the battery’s DC output to AC. The inverter should have at least 80% efficiency.
Protection and Indication System
The lantern has an electronic circuit to provide cut off provision to prevent excessive charging or over discharging of the battery. We also provide an electrical fuse with the system to protect it from any short circuit fault. In addition to these we provide two Light Emitting Diodes (LEDs) on the casing for indiating charging and deep discharging states of the solar lantern.
LED Based Solar Lantern
Solar electricity is expensive. The availability of solar electricity in a portable solar module is small. So, LED has become most suitable light source in portable handy solar lantern. The LED is best suited for small household lantern because of its small electricity consumption. Although LEDs are manufactured in different colours, white colour LED is most suitable for a solar lantern. As the electricity consumption rate of LEDs is quite low, the power ratings of the PV module used to charge the lantern is also low and if the peak power rating of a solar module is more than 2.5 W at 17 V it can be suitably used to charge a LED-based solar lantern. Became of low power consumption, the battery of this lantern is also smaller and of a lower rating. A 2.3 Ah 12 V at 20 oC sealed, maintenance-free dry type lead acid battery can be suitably used for LED solar lantern. More than 30 lumens per Watt 5 mm white LED is most suitable for a LED-based solar lantern.
