FAQ

What is PV?
PV (Photovoltaic) refers to a SOLAR PANEL. A flat panel that you place in the Sunlight which makes electricity directly from Sunlight. Photo refers to light and Voltaic refers to voltage or electricity. These panels do not produce Heat and do not heat water. They make electricity only.

What is PV MODULE?
This is a Solar Panel that makes electricity. There are 2 main types. Crystalline Type and Thin film type. Both types produce electricity but suit different conditions and weather. You must choose the correct one to fit your requirements. MPIA certified system designers will know the exact parameters and will choose the correct type of PV for the system they are installing.

What is stand alone PV?
This is for places where there is no TNB supply. 100% of the electricity is provided by Solar Power or Solar hybrid. There is no TNB bill to pay. The Solar Power system stands alone and provides all the power needed. This can also be used for Solar powered Street lights and remote power supply.

How much electricity will Solar Power systems save?
None. Solar power systems do not SAVE electricity, they are simply an alternative supply of electricity. You should use energy saving devices to save electricity and your MPIA installer will advise you.

What is a solar cell?
A Solar Cell is part of a crystalline PV module. 36 pieces of crystal are joined together to make the smallest Crystalline module. These pieces of crystal are called cells. 72 pieces make the next size and so on. They can be under 1 sheet of glass as a 36 cell module or you can use a bigger sheet of glass and make it a 72 piece module. If the cells are under 1 sheet of glass or 3 sheets of glass, the output is still the same for each set of 36 pieces. And adds up the same even under different sheets of glass. Thin Film modules do not have cells and therefore can be any size. The same addition applies and the total area always gives the same output per square metre.

How much electricity will Solar Power systems save?
None. Solar power systems do not SAVE electricity, they are simply an alternative supply of electricity. You should use energy saving devices to save electricity and your MPIA installer will advise you.

How do photovoltaic’s work?
They are very simple. ALL materials have electrons in them and in all materials, the electrons begin to move faster, in all directions, when hit by light. In any ordinary material these electrons will move in all directions equally, so some go forward and an equal amount go backwards, having no effect. In a PV cell there is a negative layer of material, (That means it has more electrons on its surface), below the material with the electrons that move and a positive layer, ( a material short of electrons), above. So you know that electrons will repel each other. Any electrons moving down will be repelled by the negative layer beneath and turn back UP. Any electrons going up will be attracted to the positive layer and keep moving UP. So now ALL the electrons are moving in the same direction. When all the electrons move in the same direction, this is called electric current.

What is the photovoltaic effect?
This is the movement of electrons by light and is how the Photovoltaic modules work. Photo refers to light and this effect is caused only by visible light. The light then creates an electric current. It should not be confused with the photoelectric effect.

What materials show the photovoltaic effect?
In general the photovoltaic effect is demonstrated by semiconductors. The first solar cells were made with selenium and gold. Nowadays a wide variety of semiconductor materials are used, as well as a few exotics which may never escape the lab.

What does light do to the material to make electricity?
Light simply knocks electrons out from the atoms of the material used. Light refers to the VISIBLE spectrum. Radio waves, microwaves, X-rays are all electro magnetic waves. Only when the electrons are guided to move in 1 direction do we have a photovoltaic panel.

What are solar cells made from anyway?
They can be made from a great many materials. The most powerful ones are made from Gallium Arsenide, the same material as LEDs. CIS, CIGS, Cadmium Telluride, Silicon, are some of the most common materials.

What is a semiconductor?
Materials, both compounds and elements, can be classified according to how well they conduct electricity. There are materials such as metals which conduct electricity well and those which conduct electricity poorly, called insulators. The universe being such as it is there are a few materials which fall in between. They conduct electricity a little bit. These materials are called semiconductors. Silicon is the most commonly used semiconductor, nowadays, but there are many others. Examples are:
– gallium arsenide
– germanium
– selenium
– cuprous oxide
– lead Telluride
– lead sulphide
– silicon carbide
– cadmium Telluride
– indium gallium arsenide nitride
– copper indium gallium selenium

What is the electromagnetic spectrum?
The first inkling of the electromagnetic spectrum was likely the rainbow. People who played with prisms noticed that white light split into a band of colours. In time it came to be realized that there was spectrum beyond blue and below red. In concrete terms, the electromagnetic spectrum is populated with light, x-rays, gamma rays, radio waves, microwaves and so on, which are all aspects of the one phenomenon – electromagnetic radiation, differing by wavelength (or the equivalent frequency (or photon energy)). As far as PV is concerned, what matters is the solar spectrum which is a black body curve for approximately 6000K. Note that at the top of the atmosphere, this is just what you get from the sun, which is called an AM0 spectrum. At the bottom of the atmosphere at high noon, the electromagnetic radiation has been filtered by the various gases and is called an AM1 spectrum. Note that for standard measurements of photovoltaic module ratings, the AM1.5 spectrum is used to allow for the fact that in the morning and in the evening the sun is on an angle and passes through a longer mass of filtering gases.

What are ThermoVoltaics?Similar to Photovoltaic’s, ThermoVoltaics may be defined as the conversion of heat to electrical voltage by a material. The difference is the wavelength of the radiation and the corresponding band gap in the material.

What constitutes a complete PV system?
This means that the system has everything needed to make it work correctly. That is Solar Panels, Inverters, batteries, controllers, connecting wires. The correct sizes and combinations MUST be designed by certified PV practitioners. A list of whom may be found on the MPIA web site.

What is an Inverter?
An electric device which converts direct current [DC] to alternating current [AC]. Solar cells produce a direct current. Unfortunately, most of the electrical devices we commonly use expect a standard AC power supply and come with adaptors to enable them to work on 240v AC. An inverter takes the DC from the solar cells and converts it to 240v AC to feed into the standard adaptors. Some small losses occur in this conversion. ( Larger losses occur within most microprocessor appliances, when converting from 240vAC back to DC)

What sorts of Inverters are there?
There are Grid connected type that put your solar power into an existing TNB power supply grid or stand alone type that just make electricity for a particular group of appliances in your own house. Some appliances can run directly on DC and do not need an inverter.

What does a Grid Connected (grid tied) system mean?
Solar energy is produced during the daytime only, while it needs to be used day and night. How to deal with this situation? Typically there are two solutions, depending upon the circumstances of the installation. Either one dump extra power during the day into some reservoir, typically a battery backup system; or one uses an inverter which can also be connected to the electric grid. In this latter case, one pumps excess power into the public grid during the day, and withdraws it at night. This is called a grid tied system. Note that each jurisdiction and electric power company will have its own rules and regulations for setting up a grid tied system.

What sorts of Inverters are there?
A Solar Tracker is a device which aims a solar panel directly at the sun in order to maximize energy output. The mechanisms for achieving this can be as varied as human ingenuity allows. In a Tropical country like Malaysia no real benefit is obtained from the use of Solar Trackers.

What sorts of Solar Trackers are there?
A broad breakdown of Solar Trackers is into those which adjust their orientation in one dimension East to West) and those which adjust their orientation in two dimensions (i.e. East to West and up to down).   Roughly speaking, there are those which adjust their orientation in one dimension. East – West) and those which adjust their orientation in two dimensions East – West and up – down).

What are Solar Concentrators?
A Concentrator is a device which takes the Sunlight and concentrates it into a smaller area. It is the SAME amount of Sunlight as reaches any solar panel but is squeezed into a smaller area. It has no advantages in PV and has many disadvantages and high losses. You still get the SAME amount of Sunlight from the Sun, which is around 1,000 watts per square metre. The concentrated Sunlight is STILL 1,000 w/M2 so NO advantage.   In order to work well, the concentrator has to be aimed at the sun and follow it exactly all day long. Thus the design considerations for trackers come into play. One commonly used design is the reflective trough, which simplifies things by removing one dimension of adjustment. This is not used in PV applications but is used to collect HEAT.

What is a voltage regulator?
A voltage regulator, aka a charge controller, is a device in a photovoltaic system which prevents over charging (aka ‘cooking’) batteries. Depending upon the sophistication of the unit, it may also prevent over-discharge of the batteries and reverse charging of the cells. It also has control over the system output.

What about lightning protection?
Commercially available surge protectors are used to protect photovoltaic systems from lightning. A properly designed system should include such protection for all elements. Note: The older spark gap arrestors were far more reliable and lasted much longer than the modern, solid state units, which are usually destroyed by the first lightning strike.

What is a blocking diode?
A ‘diode’ is a circuit element which theoretically has low resistance to current flowing one way and infinite resistance to current flow the other. It is, if you like, a one way valve. It is also called a ‘diode rectifier’.   In the case of Photovoltaic’s, a ‘blocking diode’ is a diode connected in series between solar cells and storage batteries to keep the batteries from discharging through the cells when there is low or no output. At night

What is a hybrid system?
A hybrid system is a combination photovoltaic and other power systems. Wind, Biomas, geothermal, Wave, Hydroelectric, generator or any other power source.

How do I figure out what size of system I need?
Your MPIA certified installer will do all the calculations for you. Remember it has taken the installer many years to learn how to do this and should not be attempted by inexperienced users unless the system is not important. First there are questions of type to consider.
– Is the system going to be Standalone or Grid Connected?
– Are you going to use standard AC or will DC doing?
– Are you using the system at night?

Presumably you will know this immediately. Then there are several other basic pieces of information you need to know or find out. Â
– How much energy do you use on a day to day basis? How many lights do you use? How many hours for each and every lamp. How many hours for every other piece of electrical equipment?
– How much sun do you get at your location?

To find out how much energy you use on a day to day basis, you can look at your grid utility power bills for the last year or two. An energy audit will enable you to track down where every watt goes. To find out how much sunlight you get at your location, consult any one of the several available members in this site. When you know if you are using the system at night, and how much energy you use daily, the question of review the storage capacity can be dealt with to ensure sufficient supply

What is a phantom load?
A phantom load is a hidden use of electricity which one might easily overlook in doing an energy audit. This normally equipments which are exceeded load at the point of start or shut down regardless. However low while in operations. Example air conditional units

What kind & how many Batteries do I need?
The problem of sizing a battery bank arises when designing a PV system. This discussion assumes you have done an energy audit and know how many kilowatt-hours you need your battery bank to be able to deliver. The general solution is to convert your energy required from kilowatt-hours to the amp-hour units in which the batteries are specified, while taking into account various efficiency losses

What is the Solar Constant?
The rate at which energy is received from the sun just outside the earth’s atmosphere on a surface perpendicular to the sun’s rays. Measured to be ~1365 W/m^2 by several satellites.

What about the legal & regulatory controls on PV systems?
There are several issues which concern PV systems, ignoring matters of warranty and tort which may arise.
– There is the matter of building codes; Ensuring that your power system is safe and meets municipal safety standards.
– There is the matter of regulations concerning connection to the electric grid.
– There are laws or regulations regarding
– There is issue of insurance, which relates to device testing and building codes.

Please contact MPIA; they will be able to advise you on the requirements and regulator issues

What is Net Metering?
If you take the AC output of your Inverter and run it to the mains coming from your utility power meter, any excess power you generate will feed back into the utility grid and drive your power meter backwards. This is called Net Metering. Effectively you will be paid the going retail price for your electricity up to the amount of energy you use per billing period. Any excess energy you generate will be credited at a lower rate, perhaps not at all.

What building approval do I need to add a PV system?
This need to be checked and advised – Additional policy information need. Please refer to MPIA Members

Who makes PV or PV Cells?
Most manufacturers of solar cells also make modules. Business guides and professional organizations are good place to search. Please contact members listed in the members directory they will be able to assist you on this area

Who sells and/or installs PV?
Please find list of members in the MPIA directory, they are ever willing to assist and install the PV for you.

What are these solar tiles?
Solar tiles are roofing tiles which are combine structural and photovoltaic properties in one unit. The advantage of doing this is twofold. Often the difference in price between a solar tile roof and a standard roof is negligible. And secondly, some municipalities have ‘photovoltaic hostile’ bye-laws, on the grounds of attractiveness, which discourage the use of standard photovoltaic modules.

What are Building Integrated Photovoltaic’s?
BIPV or ‘Building Integrated Photovoltaic’ an industry buzz phrase, which indicates photovoltaic modules integrated into various construction materials. Solar roof tiles are an example. Similar combination materials can be used on any other well illuminated surface.

What is the highest efficiency PV possible?
Note: A higher efficiency does NOT mean a higher output. The only answer to this is “we don’t know yet.” This is because we have yet to see the full set of photovoltaic devices which humans will develop. One sees specific numbers batted around, but they always contain the implicit or explicit assumption that solar cells will be built in a certain way.

How much do PV cells degrade with rising/falling temperature?
The electrical output of PV cells are specified for a given SURFACE temperature (usually given at 25C). The surface temperature is ambient temperature plus 25C so in Malaysia at 34C ambient temperature, surface temperature will be 59C. The behaviour of Crystalline PV, when the temperature rises above or falls below the optimum 25C given by the manufacturer, depends upon the physical properties of the photovoltaic material used. For each degree C above 25C the output will drop and the reverse for each Degree C below 25C. For Thin Film PV there is no appreciable loss with increase in temperature and this gives Thin film a big advantage in Hot climates. For precise information on a particular cell or module, see the manufacturer’s data sheet.

How do companies make standard PV measurements anyway?
They use a Laboratory test machine wit parameters that only occur in the Laboratory. These must not be used when sizing or designing a PV system and your MPIA installer will know how to size the system to real life conditions. This is the laboratory test parameter. “Light intensity of 1000 W/m^2, uniform over the active area of the module and shining perpendicular to the module surface. ( Real Sun moves 15 degrees across the Sky every hour so is never perpendicular to the real panel) “Solar spectrum at air mass 1.5 (AM1.5); that is, sunlight from space after it has passed through the atmosphere 1.5 times (or once at a 48 degree angle from vertical). Note: Malaysia has a lower Air Mass of 1). “Module temperature of 25 C. (Malaysia is 59C) “Typically, none of these parameters is real and the results of the measurement must be adjusted dramatically to reflect what the measurements will be under real conditions.

How can I connect modules with different ratings?
You do NOT. This would cause loss of power and make the system unreliable. Consult your MPIA installer.

How do you measure power?
TPower is part of the measurement of energy Power is the rate of doing work. It is an instantaneous quantity, measured in watts. A watt is 1 joule per second. Energy is measured in Kilowatt hours. Simply look at your monthly electricity bill. This shows how much energy you used, in Kilowatt hours, during the month. While power may be measured in many ways, the most common method in the context of photovoltaic power is with a watt meter. What are volts, amps, watts, joules, etc.?

Term	Measure	Definition
Newton	force	The force which will give 1 kilogram of mass an acceleration of 1 meter /second^2
dyne	force	1/10^5 nektons
joule	work	The work done when a force of 1 Newton acts through a distance of 1 meter.
erg	work	1/10^7 joules
ampere	electric current	1 ampere is a charge flow of 1 coulomb per second
ampere	electric current	“that constant current which, if maintained in two straight parallel conductors in infinite length, of negligible circular cross section, and placed 1 meter apart in a vacuum, would produce between these conductors a force equal to 2×10^-7 Newton per meter of length.”
volt	electric potential	(joules per coulomb) The electromotive force required to drive a steady current of 1 ampere through a resistance of 1 ohm
coulomb	electric charge	1 coulomb is the charge carried across a surface by a steady current of 1 ampere in 1 second
watt	power	1 watt is 1 joule per second [Power is the rate of doing work.]
watt-second	energy	1 watt of power being used over the duration of 1 second [Energy is power over a period of time.]
electron volt	electric potential	1 electron volt is the kinetic energy gained by an electron traversing a 1 volt potential difference.
amp-hour	energy	1 amp-hour is 1 amp supplied at a given voltage by a battery for 1 hour
x	y	z

What’s with this SI system anyway?
The SI, also known as the metric system, and sometimes the ‘mks’ system, has the following basic units:
– meter (length)
– kilogram (mass)
– second (time)
– ampere (electric current)
– Kelvin (thermodynamic temperature)
– mole (amount of substance)
– candela (luminous intensity)