I.          DEFINITION

A Solar Photovoltaic Lantern is a lighting system consisting of a lamp. battery and electronics all placed in a suitable housing. made of metal, plastic or fiber glass. and a PV module The battery is charged by electricity generated through the PV module. The lantern is basically a portable lighting device suitable for either indoor or outdoor lighting. covering a full range of 360 degrees. A lighting device which provides only unidirectional lighting will not be classifies as a solar lantern in the present context

II.         DUTY CYCLE

The solar lantern should provide a minimum of three hours of lighting per day under average daily solar radiation conditions of 5 kWh / sq.m. on a horizontal surface. The actual duration of lighting may vary depending on the location, season. etc

Ill.        MODELS

The solar lantern should conform to one of the following models:

 The individual specifications for lamp. battery. module, electronics. etc are given below

IV.       LAMP (FOR BOTH 12V & 6V MODELS) 

1. The lamp will be of compact fluorescent (CFL) type with a rating of either 5W or 7W.

2. For 4 - Pin type CFLs, suitable pre-heating circuit must be provided.

3. The lamp should preferably be mounted in a base up configuration.

4. The light output should be 230 + 5% lumen for a 5W lamp and 370 + 5% lumen for a 7W lamp ( see also (iii) :f VI)

V.        BATTERY

FOR 12 V MODELS:

1. The battery will be sealed maintenance free lead acid type

2. The capacity of the battery will be a minimum of 7.0 AH at 12 V at C/20 discharge rate at 20⁰ C

3. Eighty percent of the rated battery capacity should be between the low voltage and high voltage cut-off points

 FOR 6 V MODELS:

1. Spill proof positive tubular plate. flooded electrolyte type lead acid battery.
2. The capacity of the battery will be a minimum of 14 AH at 6 V at C/10 discharge rate at 20⁰ C
3. Eighty percent of the rated battery capacity should be between the low voltage and high voltage cut-off points

VI.      ELECTRONICS

1. The inverter will be of quasi sine wave/sine wave type with a crest factor less than 1.7 and he frequency in the range of 20-35 KHz Half-wave operation is not acceptable.
2. The overall efficiency of the control electronics should be at least 80%.
3. No blackening or reduction in the lumen output by more than 10% should be observed after 1000 ON/OFF cycles (two minutes ON and four minutes OFF is one cycle).
4. The idle current (the current-consumed when, the lamp is switched OFF and no charging is in progress) should not be more than 1 mA
5. The PCB containing the electronics should be capable of solder free installation and placement
6. Electronics should operate at 12 V or 6 V (depending upon the model) and should have temperature compensation for proper charging of the battery through out the year

VII.     PV MODULE

1. The wattage range of the PV modules as given in Ill (Models) above, should be at 16.40 Volts for 12 V Models ( 8.7 Volts for 6V Models ) under standard test conditions (STC). The open circuit voltage of the PV modules under STC should be at least 21.0 Volts for 12 V Models, 11.0 Volts for 6 V Models)
2. The module should preferably have an arrangement (stand) for mounting at the optimum angle in the direction facing the sun.
3. In case of thin film solar cell modules, the specified values refer to the power output after the initial degradation.
4. The terminal box on the module should have a provision for opening for replacing the cable if required
5. A strip containing the following details should be laminated inside the module so as to be clearly visible from the front side:

1. Name of the Manufacturer or distinctive Logo
2. Model or Type No.
3. Serial No.

 VIII.   ELECTRONIC PROTECTIONS

1. Adequate protection is to be incorporated under no load conditions (e.g. when the lamp is removed and the lantern is switched ON)
2. Battery cut offs & reconnects should be provided to protect it against overcharge and deep discharge conditions
3. A fuse should be provided to protect against short circuit conditions.
4. A blocking diode, preferably a Schottky diode, should be provided as part of the lantern electronics to prevent reverse flow of current through the PV module. in case such a diode is not provided with the module itself
5. Full protection against open circuit, accidental short circuit and reverse polarity should be provided

IX.      OTHER FEATURES

1. The lantern should be provided with 2 LED indicators a green light to indicate charging in progress and a red LED to indicate deep discharge condition of the battery The green LED should glow only when the battery is actually being charged.
2. A good reliable switch suitable for DC use is to be provided on the lantern A cable at least 5 meters long should be provided for inter-connection between the module and the lantern
3. The following details should be marked indelibly on the lantern
   (a) Name of the Manufacturer or Distinctive Logo
   (b) Model Number (this refers to Models indicated in Clause Ill above)
   (c) Serial Number
4. An Operation Instruction and Maintenance Manual, in English and the local language should be provided with the solar lantern  The following minimum details must be provided in the Manual
   (a) About Photovoltaics
   (b) About solar lantern
   (c) About PV module
   (d) About CFL.
   (e) About battery
   (f) Clear instructions about mounting of PV module
   (g) About electronics
   (h) About charging and significance of indicators.
   (i) Do’s and DONT’s.
   (j) Clear instructions on regular maintenance and trouble shooting of the lantern
   (k)Name and address of the person or service Centre to be contacted in case of failure
       or complaint
5. Components and parts used in the solar lantern should conform to the latest BIS specifications, Wherever such specifications are available and applicable
6. The PV module will be warranted for a minimum period of 10 years from the date of supply and the lantern (including the battery) will be warranted for a minimum period of two years from the date of supply. The Warranty Card to be supplied with the system must contain the details of the system supplied. The manufacturers can also provide additional information about the system and conditions of warranty as necessary.
7. Additional features such as a small white LED which functions as a night lamp or a socket for powering a appliance such as a fan or radio may be provided in the lantern These are however purely optional. If such features are provided, they should not interfere with the independent switching on and off of the lantern.