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End-user Manualfor Solar PV Systems

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End User ManualManual for Use and Maintenance of Solar Home Systems

Charles MuchunkuMike Okendo (Graphics)

Produced in Kenya byCamco Advisory Services (K) LtdMuringa Road, off Elgeyo Marakwet RoadP.O. Box 76406-00508 Nairobi, KenyaTel/Fax 3871027, 3877942, 3875902

5th Version, August 2012

Compilation and production of this manual is supported by the Photovoltaic Market Transformation Initiative (PVMTI) funded by the Global Environment Facility (GEF) through the International Finance Corporation (IFC) a member of the World Bank Group.

Copyright © 2012 Kenya Renewable Energy Association

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TABLE OF CONTENTS

INTRODUCTION ..................................................2

SOLAR PV SySTEM CATEGORIES.........................3

OVERVIEW OF A TyPICAL SOLAR PV SySTEM ...5

WHAT CAN A SOLAR PV SySTEM POWER? ........7MONITORING THE PERFORMANCE OF THE SySTEM ...................................................................8

MAINTENANCE ISSUES ........................................9Battery maintenance................................................9

Topping up ..........................................................9Cleaning the battery: ........................................10Corrosion on battery terminals: .......................10Maintenance Charging: .....................................11Storing batteries: ...............................................11

Replacing the battery: .......................................12Battery Disposal: ...............................................12Battery Safety ....................................................13

Module Maintenance .............................................14Cleaning the module: ........................................14Shading from trees; ...........................................15

USEFUL TIPS ........................................................16Energy Efficient lights and appliances ................16AC Appliances and Inverters ............................16Safety ................................................................17DC Appliances ..................................................17Efficient system use...........................................18Replacing fuses and lights ..................................20

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Introduction

This manual has been written for the end-user of the system, it explains how a solar PV system works, the capabilities and limitations of the system and the maintenance requirements.

Although it has been designed to be easy to understand, some of the terms used in this may be unfamiliar to the end-user. For this reason it is recommended that upon completing the installation the technician should go through this manual with the end-user.

When well designed and correctly installed, solar PV systems work. They are reliable, simple to use and their maintenance and running costs are low, spares and DC appliances are also readily and widely available.

Neglecting to undertake the little maintenance required will result in a poorly working system. In a solar PV system it is the battery that requires the most maintenance in terms of time and money. Batteries have a limited lifetime and need to be replaced after a length of use. The length of time a battery can be used before it has to be replaced depends on the how it is used and maintained. Completely discharging batteries should be avoided as it significantly reduces the life of the battery and as often as possible batteries should receive a full charge.

Solar PV systems do not provide an unlimited amount of energy and so available energy should be managed and used efficiently to avoid wastage. Each solar PV system is designed to provide a given amount of electrical energy per day to run a number of electrical appliances. This amount is based on the predetermined end users requirements. If one light/appliance is used for a longer duration than planned it means there will be less energy available for other lights/appliances in the system. In addition on cloudy days there will also be less energy available than usual.

Be sure to keep the contacts of the installation technician. In case of technical problems arising with the system contact your technician. Do not attempt to fix it yourself.

New LED lighting technology presents new opportunities for off-grid lighting. The low energy consumption of LED lights means that smaller, low cost systems e.g. from 0.5 Wp-5Wp can now be used to power these types of lights. Furthermore, these systems are designed such that installation and maintenance requirements are at a minimum. However, it is important to note that LED lights are better suited for lighting a specific area (task lighting) than to lighting a whole room (ambient lighting). These types of systems are also discussed in this manual.

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Solar PV System Categories

Solar PV Systems can be divided into 3 catergories; LED Task lighting systems, Lantern systems and typical solar systems. These categories are described in detail below

LED based LanternsAs a result of the advancements in the efficiency of white light emitting diodes (LEDs), it has become possible to create compact, affordable, rugged, and cost-effective lighting systems. These can be powered with small solar panels (e.g. 0.5 to 5 Watts) and they can operate using low-cost, rechargeable batteries typically used in mobile phone and digital cameras (e.g. Nickel cadmium, nickel metal hydride, and lithium-ion batteries). These small and portable lighting systems can also be designed for grid-based charging, where users might charge the lights at existing fee-based grid charging shops e.g. charging stations for mobile phones or batteries used in battery based systems. These systems are mainly for lighting, although some have a phone charging option. They also require little or no installation or maintenance. The rechargeable batteries typically last for 2-3 years before they have to be replaced while the LEDs last much longer. It is important to note that some of these systems do not provide an option for light or battery replacement.

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Many LED lighting products are coming to market in the Ksh 1,000 to 6,000 price range (depending on features, mark-ups, etc.), which is significantly less than the Ksh 15,000 to 80,000 cost of typical solar home lighting systems. This reduction in price makes off grid modern lighting systems affordable to a larger majority of the rural population that currently use kerosene for lighting.

As illustrated below these system are also best suited to lighting a particular area or task in a room as opposed to the whole room (ambient light).

the LED task lighting systems and basic solar home lighting systems i.e. Ksh 5,000 to 15,000. Lanterns are portable and provide good ambient lighting and are therefore suitable for small commercial (kiosks, market vendors, restuarants) and institutional (schools, clinics) applications. In addition to lighting, some lanterns are designed for phone charging and powering small radios. Lanterns also require little or no installation or maintenance and most have an option for replacing the battery and light.

CFL based Lanterns Lanterns are compact lighting systems which mostly use compact flourescent lights (often referred to as energy savers). They require a slightly larger solar panel for charging (5 - 8 Watts) and operate using a rechargeable sealed lead acid battery. Some lanterns are also designed to be charged from the grid as well as from the car. Lanterns are priced between

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Overview of a Typical Solar PV System

Key Solar PV Module

Batteries

Charge Regulator

1

2

3

4

5

6

7

8

Inverters

DC-DC Converter

Car, mobile phone charger

Car phone charger socket

Battery Box

Typical Solar Systems These are normally powered by a solar panel of larger than 10Wp. In addition to lighting and phone charging, numerous applications are possible depending on system size. However, unlike the previous 2 system categories, these systems require proper design, installation and maintenance.

The working of a solar PV system is often compared to capturing rainwater from the roof and storing it in a water tank for later use. In the case of the solar PV system, the solar PV module(s) capture the sunshine and convert it to electricity, which is then stored in the battery for later use. The amount of rainwater collected depends on amount of rainfall and on the size of the roof; similarly the amount of electricity collected by the solar PV system depends on the amount of sunshine and the size in Watts of the modules.

The battery is the electricity storage tank of the solar PV system and is only as useful as the amount of electricity collected and stored in it by the solar PV module. Like the water tank, only the electricity stored in it from the moduleover the course of the day is available for use.

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Inverters: Solar PV systems produce 12V DC electricity. Inverters convert 12V DC electricity into 240V AC electricity and are used when powering AC appliances. Inverters do not increase the amount of power available they only convert the voltage.

DC-DC Converters: Appliances that use dry cell batteries, especially radios and radio cassette players often operate at 3V, 4.5V, 6V or 9V. To use them on 12V system a DC-DC Converter which, converts the voltage from 12V to the voltage required by the appliance, is required.

Battery Box: A box in which the battery is stored to prevent it being interfered with. The box is often made of wood with ventilation openings and where necessary, a lock. Battery maintenance materials such as battery water are also stored in the box.

Solar PV modules: Produce electricity directly from sunlight. For this electricity to be useful several other components are required. These are referred to as balance of system components and comprise the following

Batteries: Batteries store the electricity generated from the solar module. Since sunlight is irregular, appliances cannot be efficiently powered directly from the solar module and are therefore powered using the electricity stored in the battery.

Charge Regulator: The charge regulator regulates the charging of the battery by the solar module and discharging of the battery by the appliances. By doing this it prolongs the life of the battery. It also acts as the connection point for the module, battery and appliances.

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What can a solar PV system power?

PV systems have their limitations and to avoid unrealistic expectations it is important that customers be aware of what PV can and cannot power. Below is a list of some common household, office and business appliances, their power rating in Watts, whether or not they can be powered by a PV system and what size of system can power them.

Appliance Appliance Size of PV System

Rating 14W - 20W 50W 80W - 100WBlack & White TV (14”) 20W 5 3 3

Color DC TV (14”) Standard 55W 5 5 3

Color AC/DC TV (15”) LCD 18W 5 3 3

Color AC TV (14”) Standard 70W 5 5 3

Color AC TV (21”) Standard 110W 5 5 5

Color AC/DC TV (21”) LCD 35W 5 3 3

VCR (Video) 20W 5 3 3

VCD/DVD player 20W 5 3 3

Radio (1 speaker) 5-10W 3 3 3

Radio Cassette Player (1 speaker) 10-15W 3 3 3

Stereo system (2 speakers) 30-50W 5 3 3

Fridge (Standard AC) 200-400W 5 5 5

Appliance Appliance Size of PV System

Rating 14W - 20W 50W 80W - 100WAir Conditioner 1500W 5 5 5

Fan (Standard AC) 60-100W 5 5 3

DC Fans 5-18W 5 3 3

Microwave 1000W 5 5 5

Desktop Comp. & Screen 200W 5 5 5

Desktop Comp. & Screen 60-100W 5 5 3(Energy Efficient)Laptop Computer 40-60W 5 5 3

Desk Jet printer 60W 5 5 3

Laser jet printer 1000W 5 5 5

Photocopier 1200W 5 5 5

Fax 20W 5 3 3

LCD Projector 200-300W 5 5 5

Iron 1000W 5 5 5

LED Lights (indoor & Outdoor) 1-20W 3 3 3

Room Light (CFL) 3-6W 3 3 3

Reading/Security Light (CFL) 10-18W 3 3 3

Mobile Phone charger 5W 3 3 3

2-way radio charger 5-10W 3 3 3

Sewing Machine 75W 5 5 3

Electric Hair Cutter 15-25W 5 3 3

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Monitoring the performance of the system

The charge controller acts as an energy manager in a Solar PV system, it regulates the charging and discharging of the battery to prevent the battery from being overcharged by the module or over discharged by the loads. The charge controller does this by disconnecting the module when the battery is fully charged and disconnecting the loads when the battery has been discharged below its recommended level. By doing this the charge controller prolongs the life of the battery.

Charge controllers are fitted with indicators to display how the system is performing at any given instant. Depending on the model of charge controller the display could be in the form of small lights or a digital display. Charge controllers usually indicate the following;

• State of charge of the battery: Whether the battery is fully charged, partially charged or completely discharged.

• State of the module: Whether the module is charging the battery or not

• State of the load: Whether or not a load is connected.

The type of display varies from controller to controller but the most common light indicators are green for a fully charged

battery, yellow for a low charge level, and red for an over-discharged battery.

End users should ensure that the installer trains them on the meaning of the various displays of the installed charge controller manual.

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Maintenance Issues

Battery maintenanceOf all the components of a solar PV system, the battery is the one that requires the most maintenance. The most commonly used batteries in PV systems are lead acid batteries of which there are two types:

• Flooded lead acid batteries in which the electrolyte (dilute sulfuric acid) is in liquid form.

• Sealed lead acid batteries in which the electrolyte is often in non-liquid form. These batteries do not require topping up with distilled water.

Sealed batteries are not maintenance intensive and are often referred to as “maintenance free” batteries. However flooded lead acid batteries require regular attention. Key battery maintenance activities are:

Topping upDuring normal battery operation water is lost and the electrolyte level drops. The lost water should be replaced with distilled water to ensure it does not drop below the minimum level indicated on the battery level. The electrolyte level should be checked at least every 2 weeks. The best time to top up the battery is after it has been fully charged.

Care must be taken not to overfill the battery and ONLY distilled water should be used.

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Corrosion on battery terminals:

Oxide accumulation on the battery terminals

After a period of use, impurities tend to accumulate on the battery terminals. These impurities reduce the conductivity of the battery terminals and should be removed. This can be done by simply filing of the impurities from the terminals. Once the battery leads have been reconnected to the battery terminals, petroleum jelly is applied to reduce the rate of corrosion.

Filing of corrosion from the terminals and application of petroleum jelly

Cleaning the battery: The exterior of the battery should be washed at least once a month with plenty of water and then wiped with a dry cloth. This is to prevent accumulation of dust and moisture from the electrolyte on the battery. If left for long periods of time without cleaning, dust and moisture on the battery will eventually lead to corrosion of the terminals and loss of energy from the battery through increased self-discharge.

Batteries should be cleaned regularly

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Battery being charged at charging station

Storing batteries:Times arise when the end-user is away and does not use his system for a long duration. Batteries discharge gradually even when there is no load connected, if left to discharge for a long period of time without being charged batteries will be permanently damaged. In such cases batteries should be left connected to the module and charge controller which will ensure that they maintain a healthy state of charge.

If this not possible, the end user should at least ensure that the battery is fully charged after every 6 months.

Maintenance Charging: It is recommended that the battery be taken to a battery charging station after every four months for an equalization charge. An equalization charge is when the battery is charged until the electrolyte bubbles, this has the dual purpose of mixing the electrolyte and ensuring that all cells have an equal charge.

During the cloudy season, batteries should be taken to the charging station more frequently to avoid them staying for long periods without a full charge.

End user taking battery to charging station

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Replacing the battery: Batteries have limited lifespan. As a battery ages it’s capacity reduces and it is unable to hold charge, as a result it cannot power appliances for the same duration as it did when new. A good indication that a battery has aged is that the charge controller disconnects the loads earlier than usual and more frequently. To confirm that your battery has expired take it to the nearest battery station for testing.

Different types of battery have different life spans as indicated:

Type of Battery Life span

Car Battery 3-12 months

Solar/Modified Car Battery 1-3 years

Sealed Battery 2-5 years

Deep Cycle Battery 4-8 years

Battery life is dependent on how they are discharged and maintained. The life of a battery will be significantly reduced if it is completely discharged frequently and if it stays for long periods without being charged. Well-maintained batteries last longer than poorly maintained ones.

For the Solar PV system to operate well batteries should be replaced when they age and can no longer hold charge.

Contact your technician when you are replacing your batteries and do not connect new batteries with old batteries.

Battery Disposal:Batteries materials such as lead and sulphuric acid are harmful to the environment. If batteries are thrown away these poisonous materials can leak into the soil and water sources. Fortunately most of the battery materials can be recycled and used in manufacturing new batteries.

Several companies in Kenya collect old batteries for recycling. When your battery expires please take it back to the dealer who will forward it to the recycling point or advice you where to take it.

You shouldn’t throw away your old battery

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Avoid open flames or sparks near the batteryIn addition to proper ventilation, open flames, cigarettes or sparks that can ignite the gas should never be in the vicinity of the battery

The following are useful safety tips that should be followed when handling batteries.

Proper ventilationWhen batteries are being charged they release an explosive gas mixture. This gas can easily be ignited by an open flame or spark from a match, candle, cigarette or electric spark. Because of this, batteries should be placed in a well-ventilated room to prevent accumulation of such gases. Ventilation should be as close to the ceiling as possible.

Take back the battery to dealers instead of throwing them away

Battery Safety

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Module Maintenances

Cleaning the module:Dust that normally accumulates on the solar PV module partially shades the module reducing the amount of sunshine it receives and as a result the amount of electricity generated and stored. During the rainy season rainwater washes most of this dust of the module. However, over long dry spells it is necessary to regularly clean the module with water to improve their performance.

Care should be taken when climbing onto the roof. A stable ladder should be used and there should always be someone to hold the ladder as you climb it.

Avoid short-circuitingAny contact between the positive and negative battery terminals with a metal conductor will lead to short-circuiting of the battery. This can cause the battery to explode and spill or spray acid that can result in serious burns. When working with batteries insulated tools or insulate one side of the tool with insulating tape. Any jewelry i.e. necklaces or rings that could cause shorting should also be removed.

Batteries should be kept in an enclosed box to prevent children or unauthorized persons tampering with them.

Carrying batteriesFrom time to time it is necessary to move the battery, for instance when cleaning or when taking it to the battery charging station. Care should be taken when carrying the battery, batteries are heavy and if carried improperly could damage ones back. There is also the risk of dropping the battery and damaging it or worse still dropping it on ones feet.

Always use the handles provided on the battery when carrying it or look for assistance. Avoid lifting and carrying batteries by yourself.

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Shading from trees; It is also important to monitor the trees growing near the solar module to ensure that growing branches do not shade the module. No part of the module should be shade at any time of the day between sunrise and sunset.

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Useful tips

Compact fluorescent

Tube fluorescent

incandescent light(bulb)

Energy Efficient lights and appliancesUse of energy efficient appliances means that the limited energy available from the solar PV system can be saved. Where possible DC lights and appliances should be used in solar PV systems, this is because they are more efficient than similar AC appliances and can be used without an inverter. Inverters are an additional system cost and use up energy during operation.

LightsIn solar PV systems, use of fluorescent DC lights is recommended over incandescent DC lights (light bulbs). Light bulbs use up to 4 times less more power to produce the same amount of light as a fluorescent light. Although fluorescent lights cost up to 10 times as much as light bulbs they last up to 12 times longer.

There are two types of fluorescent lights, the tube fluorescent and the compact fluorescent. The compact fluorescent is more efficient than the tube fluorescent and more expensive.

LED lights are becoming increasingly available and affordable. They use up to 10 times less power than an incandescent bulb to produce the same amount of light and can last up to 10 years.

LED lights

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AC Appliances and InvertersMost household electrical appliances are designed to operate on AC supply. Although solar systems produce DC, conversion to AC can be achieved by simply using an inverter. In addition to allowing the use of standard AC appliances, an AC system also results in the avoided cost of expensive cabling required for DC systems due to higher currents (especially if the house has already been wired for AC).

However inverters are a significant extra expense, consume energy during operation and are inefficient when used to power small loads. In addition, some AC appliances such as TVs, fridges and pumps require large currents to start up and therefore require inverters with sufficiently large capacity even though their operating currents may be significantly smaller.

A combination of AC and DC within the same system is also a useful alternative. The inverter can be selectively used to power essential/unavoidable AC loads while other loads can be DC. It is important to note that the since the inverter is connected directly to the battery it will, in most cases, continue to supply the AC loads even after the DC loads have been disconnected by the charge controller. If this happens frequently it can result in permanent battery damage and reduced battery life.

If using an inverter:• Only switch it on when the AC appliance(s) is being used

• Always switch off the inverter when DC loads have been disconnected by the charge controller

• Only plug in AC appliances the inverter was designed for. Large loads such as electric kettles, irons or coolers can damage the inverter if plugged in.

• Always unplug appliances from the inverter before disconnecting the inverter from the batteries

• Also the inverter should be turned off before connecting it to the batteries.

Safety Inverters give an output of 240VAC and unlike low voltage DC, this is dangerous and handling of bare AC cables or connections can result in lethal shock.

DC AppliancesIt is possible to find DC appliances for a wide range of applications. They often cost more than similar AC appliances but this cost is balanced by the savings in the energy system; cost savings through eliminating the need for an inverter and energy savings through removal of energy losses associated with inverter use.

The following appliances are available in DC: black and white/color TV’s, videos, radios, CD, VCD and DVD players, sewing machines, overhead fans, refrigerators, shavers, computers, mobile phone chargers and water pumps

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Low consumption LCD DC color TVs are now available in the market. A 15’LCD color TV can consume as little as 18W, while a 21’LCD color TV would have a power rating in the range of 30W. This is almost 1/3rd of the power that would be consumed by a standard TV. These low consumption appliances mean that smaller solar PV systems can now be used to power TVs.

Efficient system use

The amount of energy available from a solar PV system is limited, it is therefore necessary to use this energy as efficiently as possible:

• Switch off lights and appliances when not in use

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• During cloudy days it is often necessary to reduce the normal daily usage of lights and appliances so as to have sufficient energy for the most basic electricity needs.

After a cloudy day, reduce usage of lights and appliances to conserve energy

After a sunny day appliances can be used as usual since sufficient energy has been captured and stored

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Replacing fuses and lights

Over the lifetime of the system lights and fuses will have to be replaced. The type and rating of fuse or light will vary from system to system. The technician who installs the system should leave behind some spare fuses and lights, instructions on how and when to replace them and where the spares can be sourced.

KEREAKenya Renewable Energy Association

at: Kenya Industrial Research Development Institute (KIRDI)1st Floor, Engineering Block, South C Campus,Kapiti Road, Off Mombasa road,P.O. Box 42040 - 00100, Nairobi, Kenya.Tel: (+254 20) 201 4401 • Cell phone: 0715116738E-mail: administrator@kerea.orgWebsite: www.kerea.org