A stand alone solar photovoltaic street lighting system (SLS) is an outdoor lighting unit used for illuminating a street or an open area. The Solar Street Lighting System consists of solar photovoltaic (SPV) module, a luminaire, storage battery, control electronics, inter-connecting wires/cables, module mounting pole including hardware and battery box. The luminaire is based on White Light Emitting Diode (W-LED), a solid state device which emits light when electric current passes through it. The luminaire is mounted on the pole at a suitable angle to maximize illumination on the ground. The PV module is placed at the top of the pole at an angle facing south so that it receives solar radiation throughout the day, without any shadow falling on it. A battery is placed in a box attached to the pole. Electricity generated by the PV module charges the battery during the day time which powers the luminaire from dusk to dawn. The system lights at dusk and switches off at dawn automatically.

Technical Details PV Module

• Indigenously manufactured PV module will be used
• The PV module will have crystalline silicon solar cells certificate of testing conforming to IEC 61215 Edition II / BIS 14286.
• The power output of the module(s) under STC will be a minimum of 40 Wp at a load voltage* of 16.4 ± 0.2 V
• The open circuit voltage* of the PV modules under STC will be at least 21.0 Volts.
• The module efficiency will be around 12 %.
• The terminal box on the module will have a provision for opening it for replacing the cable, if required.

Battery

• Lead Acid, tubular positive plate flooded electrolyte or Gel / VRLA Type.
• The battery will have a minimum rating of 12V, 40 Ah at C/10 discharge rate.
• 75 % of the rated capacity of the battery will be between fully charged and load cut off conditions.
• Battery will conform to the latest BIS/ International standards.

Light Source

• The light source will be a white LED type.
• The colour temperature of white LED used in the system will be in the range of 5500oK–6500oK.
• W-LEDs will not emit ultraviolet light.
• The light output from the white LED light source will be constant throughout the duty cycle.
• The lamps will be housed in an assembly with IP65 protection for outdoor use.
• The temperature of heat sink will not increase more than 20oC above ambient temperature during the dusk to dawn operation.

Electronics

• The total electronic efficiency will be 85%.
• Electronics will operate at 12 V and will have temperature compensation for proper charging of the battery throughout the year.
• No Load current consumption will be less than 20 mA.
• The PV module itself will be used to sense the ambient light level for switching ON and OFF the lamp.
• The PCB containing the electronics will be capable of solder free installation and replacement.
• Necessary lengths of wires/cables, switches suitable for DC use and fuses will be provided.

Electronic Protections

• Adequate protection will be incorporated under “No Load” conditions e.g. when the lamp is removed and the system is switched ON.
• The system will have protection against battery overcharge and deep discharge conditions.
• Fuse will be provided to protect against short circuit conditions.
• Protection for reverse flow of current through the PV module(s) will be provided.
• Electronics will have temperature compensation for proper charging of the battery throughout the year.
• Adequate protection will be provided against battery reverse polarity.
• Load reconnect will be provided at 80% of the battery capacity status.

Mechanical Components

• A corrosion resistant metallic frame structure will be fixed on the pole to hold the SPV module.
• The frame structure will have provision to adjust its angle of inclination to the horizontal between 0 and 45, so that the module can be oriented at the specified tilt angle.
• The pole will be made of Galvanised Iron (GI) pipe.
• The height of the pole will be 4 metres above the ground level, after grouting and final installation.
• The pole will have the provision to hold the luminaire.
• The lamp housing will be water proof and painted with a corrosion resistant paint.
• A vented, acid proof and corrosion resistant metallic box with a locking arrangement for outdoor use will be provided for housing the battery.

Indicators

• The system will have two indicators, green and red.
• The green indicator will indicate the charging under progress and will glow only when the charging is taking place. It will stop glowing when the battery is fully charged.
• Red indicator will indicate the battery “Load Cut Off” condition.

Quality and Warranty

• The street lighting system (including the battery) will be warranted for a period of five years from the date of supply.
• The PV module(s) will be warranted for a minimum period of 25 years from the date of supply. The PV modules must be warranted for their output peak watt capacity, which should not be less than 90% at the end of Ten (10) years and 80% at the end of Twenty five (25) years.
• The Warranty Card to be supplied with the system must contain the details of the system.

Operation and Maintenance Manual

An Operation, Instruction and Maintenance Manual, in English will be provided with the Solar Street Lighting System.