Wednesday, October 8, 2014

Solar Array and Battery Bank Service and Maintenance in Solar PV System

o  SOLAR ARRAY AND MOUNTING
Solar arrays are usually maintenance free. However, a routine service can help to maintain a good energy production efficiency.

Routine Servicing for Solar Array AND MOUNTING:
o    Clean the dirt and dust accumulated in solar modules with water and soft mob/cloth during long dry season
o    Visual inspection of the modules for any kind of cracks, discoloration, damage should be done periodically. Note in case of any such case and contact the service provider for further inspection.
o    Check the solar mounting for any kind of deformation. Note the position of deformation and contact the service provider.
o    Check the nut-bolts on the mounting frame for loosening. Tight them if required. Ensure the mounting and frames are firmly secured.


o  BATTERY BANK
Battery bank may consist of individual 2V cell connected in series/parallel or 12V block battery in series/parallel as per the system requirement and design. Battery bank is the energy storage unit of the  Solar PV system. Even an individual battery has high energy density; improper leakage of this energy may result in heavy damage and cause huge loss to life and property. Please follow the safety precautions around battery bank while routine servicing and maintenance.

Routine Servicing for BATTERY BANK:
o    Cleanliness should be done regularly around the battery bank to ensure good connection at the terminals as well as preventing the contamination of the electrolyte while removing the caps. The frequency of the cleaning should be according to the environment. In places with high dust density, battery bank should be cleaned monthly. (Follow proper steps to clean the battery bank.

Steps to clean the battery bank
§  Isolate the individual cell/block. To do this first turnoff the charging system. Take proper care while handling battery not to do short circuit and spill acids.
§  Disconnect the terminals from the posts/bolts.
§  Clean the outer body with gently wet soft cloths. Be careful not to let water to enter inside cell.
§  Clean the terminals of battery until they are clean and shiny. If there is corrosion due to rusting, clean the terminals with baking soda.
§  Rebolt the connection in right terminals.
§  Apply petroleum jelly to the terminals and cover it with insulating caps.
§  If unable to unbolt the terminals, place a wet cloth over it for 2-3 hours and open it.

o    Checking the Electrolyte level to ensure that individual cells have enough electrolyte for condition. This is very important to prevent stratification of the battery bank.

NOTE: Only wet flooded lead acid battery can be refilled with distilled water.

Steps to check the electrolyte level
§  Visually inspect the level indicator provided in the battery.
§  In case required, refill the individual cell with distilled water.  

Do not refill it with tap water or rainwater collected in metal container.

NEVER REFILL ACID IN THE BATTERY


Follow the given STEPS TO REFILL DISTILLED WATER in the battery:
C  Shut down the load and charging on the system.
C  Open the cell cap which requires refilling.
C  Slowly add distilled water upto the top level as shown in indicator.
C  Do not top up the cell upto the brim. Leave at least 2cm gap between brim and electrolyte level for gassing.
C  Put back the cap.
C  Refill other cells turn by turn
C  Charge the battery bank for at least one day before reconnecting to the load.

o    Equalization charging should be done monthly to prevent hard sulphation inside the cell. This is usually programmed in the charge controller itself.


o    Check the Battery State of Charge by measuring voltage. Voltage at the terminals during various condition like instantly after charging, instantly after low voltage shutdown, etc should be measured and recorded in big systems to study the condition of the battery. Keep a battery voltage log sheet for recording.  DO NOT USE LOWLY DISCHARGED BATTERY without fully recharging. Such practices may hamper the battery life.

SAFETY FIRST (Hazards and Precautions around Solar PV System)

Solar PV system like other other electrical systems is safe when operating correctly. However, they may cause trouble when the system is suffering from malfunction. Such hazard may cause simple electric shock to deadly electrocution. Also there are some potentially dangerous hazards associated with some components.



·         SAFETY AROUND SOLAR PANELS
The owner of the system must not undertake any maintenance of the solar modules except simple cleaning.

Hazards related to solar panels
§  Many numbers of solar panels of lower voltage may be connected in series as per the system design and requirement to get higher voltage. While the lower DC voltage up to 48V does not possess potentially high danger of electric shock, the system above 48Vdc may give electric shock in wet unprotected condition.
§  Falling off roof while working
SAFETY PRECAUTIONS
§  Always wear insulated boots before working with connection of solar panels.
If the system is above 120V dc then, compulsorily wear insulated boots before working with the connection of solar panels.
The outer body of solar panels is well insulated and grounded in case of any leakage.
§  Do not leave any part of the wire connection outside junction/connection box without insulation.
§  Support yourself correctly while working with solar panels in case of narrow/difficult place.

·         Safety Around Battery Bank
The owner of the system must not undertake any maintenance to battery bank of 120V Dc or above.

Hazards related to Lead acid battery bank
§  explosion due to Hydrogen gas
§  Burning caused by dil. sulphuric acid in cells of battery
§  Shorting of positive and negative terminals leading to fire hazards
§  Electrocution caused by battery bank of 120V or above

SAFETY PRECAUTIONS
§  Do not wear any metallic objects like bracelets, chains, watches, etc while working near the battery. It may accidently short circuit the battery terminal and cause unrecoverable damages.
§  Be careful while using metallic objects and tools not to cause short circuit between the terminals of battery. Battery has very high energy density and may cause huge loss with fire hazards and explosion
§  Do not work in vicinity of battery bank if there is strong smell of Sulphuric Acid
§  Do not smoke near the battery bank
§  Do not cause any flame near the battery bank. Hydrogen is highly combustible gas.
§  Protect your clothes from spilling acids like acid resistant aprons while working near battery bank
§  Wear safety goggles to protect your eyes. In case your eyes get contaminated with acid, rinse it with clean water and seek the medical attention immediately.
§  Use baking (bicarbonate) soda to neutralize the spilled acid or cure the acid burn.
§  Seek the immediate medical attention along with first aid in case of electrocution.
§  Keep the room well ventilated


Safety Around balance of system (Bos) components
Balance of System(BOS) components includes the power conditioning and control unit of the system. The main BOS components in Solar PV System are Solar Charge Controller and DC to AC Inverter.

Hazards related to bos components
§  Electrocution due to leakage current
§  Electrocution due to insulation failure

SAFETY PRECAUTIONS
§  Follow the recommendations provided in manual of BOS components

§  Always keep the area clean and dry