Benefits of Solar Power

Solar Panels also called as Photovoltaic or PV modules convert sunlight directly  into electricity.  The solar panels reduce the amount of electricity coming from fossil fuels by supplying the electricity with clean, renewable energy from sun.

There are so many benefits of using solar panels.  Let us see what are the benefits of using the solar panels for electricity.

Benefits of using Solar Panels for electricity 

• Solar panels reduce the electricity bills dramatically.  
• Helps us from rising electricity rates :  Electricity rates are rising between 4 to 7% per annum.  The Sun, how ever never invoices you.  You are essentially purchasing 25 to 30 years of electricity at today's rates by installing solar panels for electricity.
• Advantage of Government incentives : The Government is also providing rebates and discounts and financial assistance for the people who are going to install solar panels for generation of electricity.  
• There is no pollution :  The solar panels never produce any pollution.  The only pollution that is generated in relation to solar panel is during the transportation and manufacturing of solar cells and also during mining of the materials required to produce them.
• Can be used as power source in remote locations :   Solar power is ideal for providing a source of electricity in remote places where it is either impossible or impracticable or uneconomical to install a mains electricity supply.   This includes remote locations like hills, garden sheds etc..  One example is the space where highly advanced solar panels are used to provide a source of electricity for satellites and also for international space station.
• It is renewable energy :  Solar power is renewable.  Even though Sun is not available at night, it is guaranteed to come up the next day.  This process will occur as long as life can be supported on earth  That means we will be benefited by solar power for the rest of our lives unlike fossil fuels which eventually run out.
• No noise is produced :  Solar panels have the advantages that they do not produce any noise while generating electricity.  This makes solar panels more attractive to home-owners who may have been considering a domestic wind turbine which woudl have produced significant noise.
• There is little maintenance :Solar panels never need any maintenance or little maintenance.  There are no moving parts in solar panels so there is little to go wrong with a system which was installed professionally.  The only maintenance needed is the annual cleaning of the panels which can be performed by the house owner himself.  

Advantages and Disadvantages of Solar Energy

We all know that as oil prices are increasing,  people are looking for alternative energy sources to save money.  Solar Energy is one of the alternative energy source which is available free of cost naturally.  Solar energy is nothing but conversion of sun light into usable energy.  Now a days solar energy is used for providing electricity to houses, schools, offices, universities etc.  As the traditional energy prices are on the rise, solar energy use is growing at a rate of 25% per year.  

The solar cell provide the best solution to energy problems where there is no mains electricity or there are lot of power cuts.  Solar power does not create any pollution.  As there are no moving parts for solar power system, it requires little or no maintenance at all.  There are many advantages of using solar power.  Here is a list of advantages and dis advantages of using solar energy. 

Solar energy advantages

• Solar power source coming from sun is completely free
• The production of solar electricity does not create any environment pollution. Solar energy does not produce any green house gases like oil. 
• The sun light and energy from sun does not cost you any thing.  Once you purchase the solar equipment for converting solar power to electricity, it will not cost you anything afterwards.
• As solar cells does not contain any moving parts, they require little or no maintenance
• Solar cells last longer life. Most systems have a life span of 30 to 40 years

Types of Solar Panel Installations

There are mainly three types of Solar Panel installations.  Here is a list.

Fixed Solar Panel mount:  This is the simplest and least expensive type of solar panel mounting.  The system is completely stationary.  The solar panels should always face the equator ( due south in the northern hemisphere).  The true south varies from magnetic south.  The angle of inclination of the solar panels in degrees should be set to about your latitude value. If it is slightly more than your latitude value, it will favor the winter sun. If the angle of inclination is slightly less than the latitude value, it will favor summer sun.

 

Adjustable solar panel mount :  You can change the angle of inclination of an adjustable solar panel mount 2 or 3 times in a year to account for lower angle of the sun in winter.   One good thumb rule is  Latitude + 15 degrees in winter and Latitude - 15 degrees in summer. This increases the over all solar panel output by 25%.  It is better to set the winter position in October and Summer position in March.

Tracking Solar Panel Mounts:  The tracking solar panel mounts  follow the path of the sun during the day in order to get maximum sun light.  A single axis tracker tracks the sun from east to west and a two axis tracker tracks the sun daily east to west and also the seasonal

declination movement of the sun.  The tracking solar panel mount is is the most efficient type of solar panel mount but it is the most expensive also. 

What are Solar Panels

Solar Panels are Eco Friendly electric generators.  The solar panels generate free power from sun light by converting sun light into electrical energy.  You can see a collection of individual silicon  cells in each solar panel.  The solar panels generate electricity with no moving parts, zero emissions and no maintenance. 

The photos ( light particles) produce electric current as they strike the surface of the thin silicon wafers.  A single solar cell generates about 0.5 volts.  A normal 12 Volts solar panel has 36 cells wired in series to produce about 17 to 18 volts peak output.   A 24 Volts Solar Panel contains about 72 cells.  When a solar is charging the battery, this 17 volts drops to around 12 to 14 volts ( for a 12 V solar panel) which results in 75 to 100 watts for a panel of this size.  A solar panel of 12 V has dimensions of 25 inches by 54 inches.

If you want to increase the current capacity ( more power) of a solar panel, you need to wire multiple solar panels in parallel.  If you want to increase the voltage for 24 V, 48 V or so, you need to connect the solar panels in series.  One advantage of using higher voltage output solar panels is that you can use small wire sizes for transferring electric power from panels to the charge controller or battery.  

Types of Solar Panels

 Basically there are three types of solar panels available in the market.  The details of three types of solar panels is listed below.

Monocrystalline Solar Panels :  These are the most efficient and expensive solar panels and made with Monocrystalline cells.  These solar cells uses pure silicon and it involves a crystal growth process.  Long silicon rods are cut into slices of 0.2 to 0.4 mm thick discs or wafers which are then processed into individual cells which are wired together in a solar panel.





Polycrystalline Solar Panels:  These Solar Panels are also called as Multi-Crystalline Solar Panels are made with Polycrystalline cells and are a little less expensive and less efficient compared to Monocrystalline type.  This is because the cells are not grown on single crystals but in large blocks of many crystals.   These are also sliced into wafers to produce individual cells which make up the solar panel.





Amorphous Solar Panels :  The third type of solar panels is the Amorphous solar panels which are not really crystals but a thin layer of silicon is deposited on a base material like metal or glass to create a solar panel.  These solar panels are very much cheaper but their energy efficiency is very less and so more area is required to produce the same power compared to above two types.  


Location to install Solar Panels

When you decide to install Solar Panels, the location has to be planned properly in order to get the maximum sun light on them. You should make sure that no shadows fall on the solar panels installed during the peak sun light hours ( say between 10.00 AM to 04.00 PM).  The shading of solar panels reduce their output drastically but it could also damage them.  Some suppliers  say that their solar panels can withstand shading.  So it is very important that choosing a good location without any shadows is essential requirement for a solar panel installation.  So if there are any obstacles which give shadows on the panels can be removed.

The temperature and wind loads are also important factors to be considered.  We know that we have to install solar panels in sunny and non-shady locations to get maximum output.  But heat building up is also a problem for solar panels.  The efficiency of solar panels reduces as temperature rises.  So the solar panel mounting system must allow for spacing around individual panels for air circulation so that it allows air cooling in the hot sun to reduce temperature of panels.  By allowing air flow around the solar panels, they not only become cooler  but the wind resistance also reduces.

What is Solar Energy?

Solar Energy is nothing but the energy from Sun.  There are two types of solar energy - Thermal energy and Electric energy.  

Thermal Energy 

You can see thermal energy everywhere.  It heats our earth, our bodies and our homes.  The thermal energy dries up our clothes and also we get products from it like sun-dried tomatoes.  All this for free...  The Thermal energy is also used to heat water for house hold use and also water in swimming pools. 

Electric Energy

The electric energy uses the sun light for producing electricity by using solar cells or photovoltaics.  It can be produced in three ways.

• Stand alone system
• Grid-connected system
• Back up system

The stand alone system is also called as Solar Home System.  This system is not connected to the grid.   This kind of systems are normally installed in remote areas where you do not find electricity.  It is very cheap to install solar energy system than laying cables for electricity to the remote site.  

The Grid-Connected system is a system where the utility supplied electricity is connected to the house and at the same solar energy is also connected to the house.  Electricity is supplied firstly from solar energy  and if required any need is there, it is supplied by grid.

Back up is a system connected to an unreliable grid or one of poor quality.   These  types are usually installed in areas where a lot of power blackouts occur. A small system will service the most important electrical appliances and lights, but a bigger system will be required to keep the fridge running during a blackout.

What is a Charge Controller in a Solar System

What is a Charge Controller?

 As we know that  we get more voltage from the solar panels as the brightness of sun increases.  The excessive voltage could damage the batteries if the batteries are directly connected to the solar panels.  A charge controller is a device which is used to maintain the proper charging voltage on the batteries.  When the input voltage from the solar panels increases, the charge controller will regulate the charging to the batteries so that over charging is prevented.  A Charge controller regulates the voltage and current coming from the solar panels to the battery.  Most of the 12 Volts solar panels produce 16 to 20 volts and if connected directly to the batteries will damage them due to over charging.  Most of the batteries need around 14 to 14.5 volts to get fully charged.

Modern Charge Controllers 

Most of the modern charge controllers undergo what is known as 3-stage charge cycle which is shown below.

• Bulk Phase : During this phase of charge cycle, the voltage rises gradually to the bulk level ( normally 14 volts) while the batteries draw the maximum current.  Once the Bulk level of voltage is reached, the absorption stage starts.
• Absorption Phase :  During the absorption phase, the voltage is maintained at the Bulk level for some specified time which is typically 1 hour while the current gradually tapers off as the batteries get charged up. 
• Float Phase :  During this phase the voltage is lowered to a float level ( normally 13.3 volts to 13.7 volts) and the batteries draw a small current until the next cycle.

    You can see the relation ship between the current and voltage during the above 3 phases of charge cycles in a graph which is shown below.

Is the charge controller always needed?

No,  it is not always needed.  Generally a charge controller is not required for a small systems like 1 to 5 watt solar panels.  A general rule is that if a solar panel puts out about 2 watts or less for each 50 battery amp-hours, then a charge controller is not required. 

Why 12 volts solar panels actually produce 17 volts 

You may get a doubt "Why solar panels are not designed just to produce 12 volts".  The reason is that if you design a solar panel to produce just 12 volts,  the panels will provide power only under perfect conditions and full sun.  This is not the situation in most of the places.  The panels have to produce extra voltage so that when the sky is cloudy and sun is low, you should still get some output from the panels.  A fully charged 12 Volts battery is around 12.7 volts at rest so the solar panel has to at least produce more than 12.7 volts in worst conditions.  

One thing to remember is that the solar panels work best at cooler temperatures.  A solar panel rated at 100 watts at room temperature produces 83 watts at 110 degrees temperature.

A solar charge controller regulates the 16 to 20 volts output of the solar panels down to what the battery needs at the time.  It may vary from 11 volts to 14.6 volts depending on the state of the charge on the battery, the type of battery and in what mode the controller is in and the temperature. 

The charge controller is installed between the solar panel array and the batteries.  The charge controller maintains the charge on the batteries using the 3 stage charge cycle described above.  The power inverter can also charge the batteries if it is connected to the AC utility power.

Summary :  If you are  using four 80 to 100 watts solar panels,  your charge controller should be rated up to 40 Amps.  Even though the solar panels normally do not produce that much current, there is an 'edge of cloud effect'.  Due to this phenomenon I found that my four 7.5 amps panels ( 4 x 7.5 = 30) pump out more than 35 Amps which is well over the rated 30 Amps maximum. 

What is needed for Solar Power System Installation

General Requirement of Solar Panel Installation at homes

Are you planning to install solar power system for your house?  Do you know what is required and where to start?  If you plan to install a solar power system for your house, then you need to know some basic requirements for installing solar power system.

Besides from installing solar panels on the roof top, some additional equipments are needed for providing power to your house from solar energy.  Once you buy all the equipments and install the solar panels and they are working, there will be little or no maintenance and no additional cost.  Let us now see what is the general requirement for installation of Solar Energy system.

Once you have a general understanding of how the solar energy system functions, it will be much easier to choose the right parts.  In this article you can see the brief description of a standard grid tie system ( or on the grid system).  Staying connected to the power grid means that you still receive the power from the utility company and you can even sell your excess power back to the utility company.

What are the main components of a solar energy system for your house

In the on the grid system,  the electricity is generated by many solar modules ( or PV solar panels).   There will be a shut off switch which separates the panels from the rest of the system.  This is required for you to be safe in case of any repairs.  The next equipment in the list is the solar inverter which turns the Direct Current (DC) from solar panels into Alternating Current (AC) for the house.  From the inverter, the power goes to the circuit breaker box and distributed through out the house. A power meter which is capable of measuring power going into or being pulled from the grid will measure amount of electricity which is needed or sold back to utility company.

Choosing the correct solar panels

You are supposed to know few basic things before proceeding to design the solar power system for your house..  You should know how much energy is needed to be produced, amount of space available on roof top,  and what you can afford to buy.   The best starting place is to know how much you consume in a month.  With this information, you can estimate what is the size of solar array is needed to produce the required amount of energy, or how much energy can be produced in a given place available or how much can be produced with the money you have.

Once you know about your monthly target output in KWh, it is very easy to calculate the size of solar array needed.  An average house may need about 600 KWh every month but it differs from place to place.  Divide this number by the peak sun hours you receive each day to know the size of your solar system.  The Peak Sun Hours are the number of hours per day where the solar irradiance equals to 1000 watts/square meter.  The average peak sun hours at any place is 5 hours.  An example would be,  if you use 1000 watts daily, and you receive 5 hours of sun light per day, then you need a 200 watt panel to completely cover your usage. 

Now take your monthly KWh number ( 600 Kwh) / 30 days / month = 20 Kwh per day. Do you know what size of solar array makes 30 KWh per day?  This depends on peak sun and let us take it as 5 hours.  So 20 KWh / 5 peak sun hours = 4 KW array or 4000 watts.  For a 4000 watts array, you need 20 Nos. of 200 Watt panels, or 16 Nos. of 250 Watts panels. 

Now you know how much power is needed, start designing the solar array.  There are two different kinds of solar panels. -  traditional crystalline solar modules and thin film solar panels.
Crystalline are large modules and expensive but more efficient than thin film panels,  The thin film models comes on a flexible roll of metal or plastic which can be applied on any flat surface like metal roof.   It is very simple to install this kind of panels.  But if the place is less on the roof top, then choose the high-efficiency crystalline panels.