Installation of 200W_solar_panel_in_a_house

Installation of 200W solar panel in a house.

Anthropower

Introduction:

India lies in the sunny regions of the world. Most parts of India receive 4–7 kWh (kilowatt-hour) of solar radiation per square meter per day with 250–300 sunny days in a year. The highest annual radiation energy is received in western Rajasthan while the north-eastern region of the country receives the lowest annual radiation.

The features that make it an attractive and a lucrative option include global distribution, pollution free nature, and the virtually inexhaustible supply.

Solar Panel:

Fig1: A 270W polycrystalline module

Manufacturing Technology:

3 key elements in a solar cell form the basis of the technology: 1) Semiconductor which absorbs light and converts it into electron-hole pairs. 2) Semiconductor junction, which separates the photo-generated carriers (electrons and holes) 3) Contacts on the front and back of the cell that allow the current to flow to the external circuit.

The two main categories of technology are defined by the choice of the semiconductor: Either crystalline silicon in a wafer form or thin films of other materials.

A grid interactive roof top solar PV system comprises the following equipment:

1) SPV Power Source

2) Inverter (PCU- Power Conditioning Unit)

3) Mounting Structure

4) AC and DC Cables

5) Earthing equipment /material

6) Junction Boxes or combiners

7) Instruments and protection equipment (disconnect switches and fuses)

1) SPV Power Source: Solar Panel as in fig 1

2) Inverter (PCU- Power Conditioning Unit)

Fig 2: Solar Power Conditioning Unit

It is the most important component.

Inverter does:

1) The inverter converts the DC power of the array into AC.

2) The output of the inverter synchronizes automatically its AC output to the exact AC voltage and frequency of the grid.

Solar Inverters:

A Solar inverter or PV inverter is a type of electrical inverter that is made to change the direct current (DC) electricity from a photovoltaic array into alternating current (AC) for use with home appliances and possibly a utility grid.

Solar inverters may be classified into three broad types:

• Stand-alone inverters, used in isolated systems where the inverter draws its DC energy from batteries charged by photovoltaic arrays and/or other sources, such as wind turbines, hydro turbines, or engine generators. Many stand-alone inverters also incorporate integral battery chargers to replenish the battery from an AC source, when available. Normally these do not interface in any way with the utility grid, and as such, are not required to have anti-islanding protection.

• Grid tie inverters, which match phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply, for safety reasons. They do not provide backup power during utility outages.

• Battery backup inverters. These are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid. These inverters are capable of supplying AC energy to selected loads during a utility outage, and are required to have anti-islanding protection.

Protection and Controls:

1. Inverter is provided with islanding protection to isolate it from the grid in case of no supply, under voltage and over voltage conditions so that in no case there is any chance of accident. In case of a power cut, the PV module too ceases to provide any power. In such a case, the backup DG (Diesel Generator) set is utilized.

2. In addition to above, PV systems is provided with adequate rating fuses, fuses on inverter input side (DC) as well as output side (AC) side for overload and short circuit protection and disconnecting switches to isolate the DC and AC system during maintenance.

3) Mounting Structure:

The frame is made up of anodized aluminum; its thickness on the surface of the frame is 25 micron. The component frame have four sets of screws and one set of holes connecting to the ground, completely meet the international authority’s demand.

Fig 3 : Mounting Structure

4) AC and DC Cables:

Fig 4: AC/DC wire concept

5) Earthing equipment /material:

6) Junction Boxes or combiners:

Junction box has good water-proof and sealed functions

7) Instruments and protection equipment (disconnect switches and fuses):

Seal material: Anti-aged EVA (Encapsulated Resin) and anti-climate good TPT (Tedlar-Polyester-Tedlar) material

Connections:

On the solar module, connect the positive home run cable to the positive output cable, and connect the negative cable to the negative of the home run cable pushing collectors all the way in.

Fig 5 : Connection b/w wires and their encapsulation

When you have made direct connections, use a digital multimeter to measure the voltage and current output of the module. Record the measurement results.

• This information is needed to check for solar module wiring mistakes, and it will also be needed by the electrician who makes the connections to the inverter.

Then the wire is connected to the Solar Power Conditioning Unit, which converts Dc power of the module into AC which synchronizes automatically its AC output to the exact AC voltage of the grid.

The devices are connected with the inverter. The extra supply, if left is sent to the grid, for other’s use, which the producer is paid for, by the government.

Fig 6: Illustration

The power generating capacity of a photovoltaic system is denoted in Kilowatt peak (measured at standard test conditions of insolation 1000 W/m2).

Standard Flow in a house:

Fig 7: Working model and use of excessive power produce to power grid.

Steps to follow:

Step 1: Mounting of the Solar Panels on the roof, tilted at an angle equal to latitude of the place in south direction. The mounting has been discussed in the Fig 3.

Mounting methods:

1. Mounting with Bolts

The module must be attached and supported by at least four bolts through the indicated mounting holes.

2. Mounting solar modules with bracket on flat roof and ground

Fasten bracket on flat roof or ground first, fasten solar modules on bracket, use nuts to fasten

bracket. The bracket would endure 20 years, and is made of anticorrosive material. Temperature zinc steels and Stainless steel is recommended.

3. Other

The recommended standoff height is 5 cm. If other mounting means are employed this may affect the UL Listing.

Direction of module installation: PV module are rectangle shaped; PV module array

longitudinal installation (the way that installs the module by long side longitudinal) is mostly

used because the transverse installation (the way that installs the module by long side

transversely) has less rain cleaning ability.

Precautions:

Exercise caution when wiring or handling modules exposed to sunlight. Completely cover all modules with an opaque material during installation to prevent electricity from being generated.

When disconnecting wires connected to a photovoltaic module that is exposed to sunlight, an electric arc may occur. Arcs can cause burns, start fires or otherwise create safety problems. Exercise caution when disconnecting wiring on modules exposed to sunlight.

Do not use mirrors or other hardware to artificially concentrate sunlight on the module.

Use appropriate safety equipment (insulated tools, insulating gloves, etc) approved for use on electrical installations.

The module should not be shaded at any time of the day. If the module is in shade it, suffers from shading effect:

Shading effects on Solar PV systems: From case studies it is known that PV systems with the same nominal power generate quite different energy yields due to different shading patterns. The common problems are:

1. Reduction of power output: As the insolation is reduced by shading we get a reduced photo current. As cells are in series connection, the current for all the cells is reduced.

2. Thermal stress on the module: Depending on the level of shading, the PV generator circuit and the load the voltage of shaded cells might reverse. In this case they operate in the blocking state as a resistive load. The losses in the individual cell can increase the cell temperature dramatically and overheating might occur.

In order to overcome some of the problems related to shading, by-pass-diodes are connected parallel to a number of solar cells. Under normal operating conditions the diodes are blocked as compared to the voltage generated by the cells. When shading occurs the reversal of the voltage can be observed in that specific section and now the by-pass diode in parallel will conduct the current. The results are:

The current of the unshaded section flows through the by-pass diode and the power/voltage characteristic shows a second local maximum

The shaded cell is only loaded with that fraction of power produced by the remaining unshaded cells of that section

The use of by-pass diodes results in some drawbacks as well:

• Higher cost for the module production and assembly problems of the by-pass diodes

• Losses in the by-pass diode due to shading

• Matching problems between the solar inverter and the photovoltaic generator because of the second local power maximum might not be included in the range of operation of the inverter.

Do not install the module near equipment or in locations where flammable gases can be generated or collected.

Step 2: Testing:

It is best to test the solar array before mounting to avoid having to take it down again. To do this, turn it over and lay it on the ground face up. Make sure you have enough people helping to avoid twisting or dropping the solar array.

Using a multimeter set to an appropriate DC Voltage range, measure the voltage between the two cores of the output cable. It should be equivalent to the open-circuit voltage of onesolar panel multiplied by the number of solar panels in series. That is, about 20 V for a 12 V system, 40 V for a 24 V system and 80 V for a 48 V system. 80 Volts is a dangerously high voltage, and 40 Volts is enough to give a nasty shock in the wrong circumstances; take care when performing these measurements and cover the solar array with an opaque material before connecting the meter if in any doubt.

Once this test is complete it is advisable to make the solar array safe before lifting it into place. There are two ways of doing this; either cover it with an opaque material or connect the cores of the output cable together to short-circuit the solar array. This will not cause any damage and is my preference.

Step 3: Electrical Installation

Grounding:

There is the grounding hole and grounding marking along either edge of the frame indicating a ground bonding location. Frames must be grounded and bolts, washer must be of stainless steel. The wire must have no nick. Make the grounding wire connect to the bolt and tighten it.

Precautions:

Ensure that positive and negative DC wires run closely together avoiding loops.

Completely cover system modules with an opaque material to prevent electricity from being generated while disconnecting conductors.

Do not touch bare conductors or other potentially energized parts.

Inverter output is mains voltage AC and can be lethal. Treat as for any other mains supply.

Solar arrays generate electricity when exposed to the sun, whether connected to

control equipment or not. Treat solar array output cables as live and cover solar

array when making connections.

The open circuit voltage of a solar array is significantly greater than the system

voltage. For example a 48 Volt array can have an open circuit voltage of nearly 90

Volts, which can be lethal to children, the elderly or anyone with a heart condition.

Batteries can produce currents of hundreds or even thousands of amps giving rise to

the risk of fire. Take great care to protect the battery terminals from shorting by tools

and remove all jewellery.

Use such protections for electrical installation:

Fig 8: Photovoltaic Fuses:

Fig 9: Photovoltaic Fuseholders :

Fig 10: Surge Protective Devices

Fig 11: PV Safety Solutions

Fig 12: Power Electronics Solutions

Fig 13: Wire Management

Chemical

Lead acid batteries contain dilute sulphuric acid and liberate hydrogen when charging. Observe the following precautions:

Take great care when filling batteries with electrolyte; wear suitable protective clothing

including eye protection and carry out in a well ventilated area, preferably outdoors.

Do not smoke near batteries and ensure room is well ventilated.

Take care to prevent arcing near battery terminals as explosion may result. Keep first aid and eyewash equipment close at hand when working on batteries.

Handling Batteries and solar arrays present certain hazards in handling as follows:

Lead acid batteries are extremely heavy. Use appropriate lifting gear and ensure adequate

help is available.

Most solar panels are made from glass. Treat as fragile. Installing solar arrays may involve working at height. Observe all necessary precautions and employ the services of a qualified rigger or roofer if necessary.

General Precautions:

Batteryless grid type system vs Off grid system:

Batteryless grid- tied systems are simple to understand and design, with only two primary components: PV modules and an inverter that feeds AC electricity back into the electrical system to offset some or all of the electricity otherwise purchased from the utility. These systems are cheaper, easier to install and maintain, and operate more efficiently than battery-based systems of comparable size. Their main drawback is that when the grid goes down, they cannot provide any energy for you to use. If the grid in your area is mostly reliable and outages are infrequent, these systems can offer the best payback for the least price.

Battery: Installation of the battery may be as simple as taking a wet-charged or sealed battery out of a box and placing it on a firm and level surface. Alternatively it may involve mixing acid to the right concentration and filling the batteries on site. Siting: The batteries need to be mounted such that they are secure, i.e. they can’t fall over, they are protected from unauthorised access and away from sources of ignition. The room or container that they are in should be ventilated so as to allow the hydrogen produced by charging to escape. This applies even to sealed batteries as they are able to vent excess gasses should the charging system malfunction. Practically this is most likely to mean one of two things: • On a solid floor or racking within a locked and well ventilated room. • In a purpose designed battery box. It is important that it is possible to gain access to the batteries in order to perform maintenance. In the case of a sealed battery this means the terminals, but for a vented battery it may mean access to the level markings on the side and the filling caps.

Sealed batteries

Sealed batteries of both gel and AGM types are always supplied filled and usually charged. It may be necessary to give them a refresher charge before putting them into service. This

should be performed with a regulated mains charger if possible. If this can’t be done for any reason then the system should be used as little as possible for the first 24 hours in order to allow the batteries to become fully charged.

Wet batteries

When batteries are supplied already filled with electrolyte, they are usually charged and are

treated in the same way as described for sealed batteries.

Dry-charged batteries

Some wet batteries are supplied dry-charged. This means that they have been charged, the electrolyte emptied out and the battery dried and sealed. It is important that it remains

sealed if it is to be stored before being put into service. Once it is required, the seals should

be removed and dilute sulphuric acid of the correct specific gravity used to fill the cells to the filling mark. The acid will usually be supplied with the battery. The battery should then be

allowed to stand for a period of time to allow any air to escape.

A dry charged battery, once filled, will achieve about an 80% state of charge. For this reason it

must be charged before putting into service. Normally this will be specified by the

manufacturer as being at a specific voltage for a particular amount of time. Again it should be accomplished by means of a mains operated charger if possible, although it may be possible

to use the solar system to provide this charge if the loads are disabled for a certain amount of

time.

Dry uncharged batteries

Sometimes batteries, normally large cells, are supplied in a dry uncharged state. It is critical

that the manufacturer’s instructions are followed to the letter as the initial charge is

important to the formation of the plate structure. Normally they will be filled as with dry-charged batteries and then subjected to an extended charge, often taking some days. This

must be performed with the correct type of charger and it is advisable to avoid purchasing batteries in this state if possible. If wet batteries have to be transported by sea or air the best

option is to obtain them in a dry-charged state with the acid in suitable packaging as advised

by your shipping company.

Mixing acid

It may sometimes be necessary to mix your own electrolyte from concentrated sulphuric acid

and distilled water. This should be avoided unless absolutely necessary, for instance in

developing countries where it may be impossible to purchase ready made electrolyte and

shipping it from the manufacturer is impractical. It is essential that the sulphuric acid and

distilled water are of the highest purity.

Before you start collect together the following items:

Safety clothing, including a chemical splashes apron, face shield and suitable gloves.

A suitable non-metallic mixing vessel and stirrer. Glass is ideal although you may have to

use whatever is available such as a plastic bucket and wooden stick. I write from experience on this.

A glass thermometer calibrated from at least 10 - 80º C.

A battery hydrometer, which can be bought from a battery specialist or tool shop.

A container to hold the finished electrolyte. A plastic drum is ideal and should be marked

“Sulphuric acid. Highly corrosive.”

It is important that you always add acid to water and never the other way round. In this way,

you are never diluting concentrated acid, which can cause it to boil explosively with very

serious consequences. Mix a little at a time, add the acid in small amounts and stir thoroughly. Bear in mind that it will become hot.

Each time you add some acid, check the specific gravity by drawing a little electrolyte into the

hydrometer and expelling it, then drawing in enough just to lift the float. Read off the specific

gravity from the scale and record. Then measure the temperature of the electrolyte and add 0.001 to the reading on the hydrometer for each degree Celsius above the specified temperature.