FAQs (Frequently Asked Question)

What is Solar Electricity or “PV”? Or What do we mean by Solar Electricity?

The word itself helps to explain how solar electricity or solar electric technologies work. First used in about 1890, the word has two parts: photo, a stem derived from the Greek philosopher, which means light and volt, and a measurement unit named for Alessandro Volta (1745-1827), an innovator in the study of electricity. Therefore, solar electricity can literally be translated as light-electricity. In addition, that is just what solar electricity materials and devices do; they convert light energy to electricity, as Edmond Becquerel and others discovered in the 18th Century.

How can we get electricity from the sun?

When certain semiconducting materials, such as certain kinds of silicon are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. A solar electric or solar electricity cell converts sunlight to electricity in the basic physical process. Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transmitted to an electron in an atom of the PV cell (which is actually a semiconductor). With its newfound energy, the electron escapes from its normal position in an atom of the semiconductor material and becomes part of the current in an electrical circuit. By leaving its position, the electron causes a hole to form. Special electrical properties of the PV cell—a built-in electric field—provide the voltage needed to drive the current through an external load (such as a light bulb).

What are the components of a Solar Electric system?

A PV system is made up of different components. These include PV modules (groups of PV cells), which are commonly called PV panels; one or more batteries; a charge regulator or controller for a stand-alone system; an inverter for a utility-grid-connected system and when alternating current (ac) rather than direct current (dc) is required; wiring; and mounting hardware or a framework.

How long do Solar Electricity systems last?

A PV system that is designed, installed, and maintained well will operate for more than 20 years. The basic PV module (connected, enclosed panel of PV cells) has no moving parts and can last more than 30 years. The best way to ensure and extend the life and effectiveness of your PV system is by having it installed and maintained properly. Experience has shown that most problems occur because of poor or sloppy system installation.

What is the difference between PV and other solar energy technologies?

There are four main types of solar energy technologies:

  1. Solar Electricity systems, which convert sunlight directly to electricity by means of PV cells made of semiconductor materials.
  2. Concentrating solar power (CSP) systems, which concentrate the sun’s energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity.
  3. Solar water heating systems, which contain a solar collector that faces the sun and either heats water directly or heats a “working fluid” that, in turn, is used to heat water.
  4. Transpired solar collectors, or “solar walls,” which use solar energy to preheat ventilation air for a building.

How do I know if I have enough sunlight for PV?

A Solar Electricity system needs unobstructed access to the sun’s rays for most or all of the day. Shading on the system can significantly reduce energy output. Climate is not really a concern, because PV systems are relatively unaffected by severe weather. In fact, some PV modules actually work better in colder weather. Most PV modules are angled to catch the sun’s rays, so any snow that collects on them usually melts quickly. There is enough sunlight to make solar energy systems useful and effective nearly everywhere in Pakistan.

Why should I purchase a solar system?

People decide to buy solar energy systems for a variety of reasons. For example, some individuals buy solar products to preserve the Earth’s finite fossil-fuel resources and to reduce air pollution. Others would rather spend their money on an energy-producing improvement to their property than send their money to a utility. Some people like the security of reducing the amount of electricity they buy from their utility because it makes them less vulnerable to future increases in the price of electricity. If it is designed correctly, a solar system might be able to provide power during a utility power outage, thereby adding power reliability to your home. Finally, some individuals live in areas where the cost of extending power lines to their homes is more expensive than buying a solar energy system.

How is a solar electric system designed, installed, and maintained?

You could install a Solar Electricity or solar electric system yourself. However, to avoid complications or injury, you will probably want to hire a reputable professional contractor with experience in installing solar systems. PV systems have few moving parts, so they require little maintenance. The components are designed to meet strict dependability and durability standards so they can stand up to the elements. However, they are sophisticated electric systems, so installation usually requires the knowledge and experience of a licensed electrical equipment contractor.

Where can I find someone who designs, installs, and maintains Solar Electricity systems?

We suggest you look for a PV installer or equipment provider in the telephone directory under “Solar Energy Equipment and Systems Dealers.” It is a good idea to select a designer or installer of solar energy systems from the list in your local yellow pages by first asking for information from several of them about their experience with PV systems as well as how much their services and products cost. With a system designer, you can discuss power requirements or hot water needs for your building, sunlight availability, and other important factors, and determine the type of system that has needed to meet your needs. System designers and installers should be able to provide you with cost estimates and other pertinent information. If your house is not yet designed or built, it is important to make the building as energy efficient as possible to reduce your PV system’s energy requirements.

How much does a solar energy system cost, and how much will I save on utility bills?

Unfortunately, there is no single or simple answer. However, a solar rebate and other incentives can reduce the cost of a PV system. This cost depends on a number of factors, such as whether it is a stand-alone system or is integrated into the building design, the size of the system, and the particular system manufacturer, retailer, and installer.

How much maintenance do Solar Panels require?

Solar panels generally require very little maintenance since there are no moving parts. A few times a year, the panels should be inspected for any dirt or debris that may collect on them. Always make sure you are safety conscious when inspecting panels and do not take any needless risks! If your panels are too high up on the roof to see very well from the ground, use caution with ladders.

For general cleaning, simply use a standard garden hose to wash the face of the panels either during the early morning or in the evening. Avoid spraying cold water on hot panels or you may crack them.

Cleaning is an important key aspect of solar panel maintenance. The dustier your area, the more frequent inspection is recommended. This ensures that dirt, grime, bird droppings, and debris do not block the sun from efficient absorption by the panels.

There are a few ways you can clean your panels. The first (and easiest) way is to rinse off dust with a standard garden hose. If the panels seem to need a little more cleaning than the hose offers, a soft, spongy squeegee on a long pole (like the ones used to wash tall windows) can be used, along with some soapy water. Then use the hose to rinse off any excess suds.

If the panels are too high to reach without climbing up a ladder, it may be best to leave the cleaning for the professionals. We advise you to contact your solar system installers.

We generally don’t like rainy days since cloudy days mean less power production but consider it a blessing if there are a few days of it. Free cleaning? I’ll take it!

As owners, the goal is always to get the best return on your investment, so make sure your panels are performing at maximum capacity and save energy whenever possible.

How often should I clean my Solar Panels?

When someone gets a new rooftop solar installation, the second question they always ask is “how often do I need to clean my solar panels.” We’ll answer that question here, taking into account the different effects of rain, dust, and electric rates.

Rooftop solar panels get dirty primarily from wind-blown dust and pollen. As panels get dirtier, their output declines. A small amount of soiling — say a light dusty film — may only cause a 5 percent output decline. However, when panels get very dirty — perhaps in an agricultural area or location that does not get regular rainfall — the output decline can be greater than 20 percent. A good heavy rainstorm will usually wash away most of the accumulated soiling.

We use the term “usually” because, on panels that are tilted at about 5 degrees or less, the rain may leave a puddle of muddy debris along the lower edge of the panel. When this puddle dries, sometimes a thick layer of dirt accumulates along the lower row of cells (sometimes moss and weeds may even grow in these areas). Depending on the design of the system, this small accumulation of dirt can cause a very significant decrease in output. So the answer to the question: “how often should I clean my solar panels” really depends on five factors: your location (does it rain regularly or only during certain months), the tilt angle of your panels (steeply tilted panels tend to stay much cleaner than panels that are close to horizontal), the amount of wind-blown dust, your electric rate (if your electric rate is high then it is more worthwhile to clean your panels), and the cost to clean your panels. Unfortunately, it is often the case that the installation date the last time a solar system owner ever looks at their panels – until something goes wrong. We recommend that panels should be cleaned and inspected at a minimum once every two months. Cleaning at regular intervals prevents the buildup of residue and keeps your panels operating optimally at all times. Regular checks can also prevent cracks or fire risks from developing into something worse – but you will need to know what you are looking for in order to identify these issues in the first place.

How should you clean the panels?

Wherever and whenever possible, panels should be cleaned using purified water and a soft brush. Panels should not be cleaned with a pressure washer, as doing so could result in cracked glass. Abrasives and chemicals should also be avoided, as both can result in ‘rough spots’ on the panels where dirt is likely to accumulate. Also, remember that you should never put pressure on the panels by stepping or putting weight on them.

Can solar system work at night?

Technically, no. Solar panels do not produce energy at night. The photovoltaic cells in solar panels must have sunlight to create electricity. However, that is not the bottom line. Solar panels offer two indirect nighttime energy solutions

Solar panels work hard all day producing electricity from the sun. They also have supportable solar energy solutions at night. You can continue benefiting from their energy production after sunset through net metering and solar battery storage. So, when you ask, how do solar panels work at night? These are the two indirect ways that they can.

Solar energy is changing the way we power our lives. Electric grid connection with net metering and solar battery storage both allow your solar energy system to provide electricity when your solar panels are resting—so you can rock around the clock.

Through Net metering you can sell extra electricity to national grid.

Can solar energy be stored?

Solar panels cannot produce energy at night or during cloudy periods. However, we can use batteries to store electricity: the photovoltaic panels charge the battery during the day, and this power can be used in the evening.

Is solar energy efficient?

Calculating efficiency is simple. If a solar panel has 20 percent efficiency, which means it is capable of converting 20 percent of the sunshine hitting it into electricity. The highest efficiency solar panels on the market today can reach almost 23 percent efficiency. The average efficiency of solar panels falls between the 17 to 19 percent efficiency ranges.

Why solar energy is expensive?

Utility rates seem to keep getting higher every year, don’t they? Yet sunlight is free and plentiful.

Accessing power straight from the source makes more logic than paying for it indirectly from your local power plant. Clearly, solar power is more economical than “regular” or standard electricity. According to the World Economic Forum (WEF), installing new solar panels is cheaper than a comparable investment in coal, natural gas or other fossil fuels.

Solar system vs fuel generator.

Solar power has started to go mainstream. But, if you are not quite ready to power your home primarily solar electricity, why not try using solar energy to replace your backup power?

You may already be familiar with gas or diesel-powered generators. Solar systems are cleaner, safer, and may even make more financial sense. While fuel-powered generators, produce pollution and are expensive.

Can I use solar system without inverter?

Yes, you can use a solar system without inverter by connecting solar panels to batteries of UPS by using a charge controller.

Can I use solar system without battery or solar system without battery in Pakistan?

A hybrid solar inverter can work without batteries. This type of system is attached to solar panels and to the power grid, which supplies power from both.

The energy produced by the solar panels is directed to the house for use and they do not need to produce all the electricity to run an entire household as shortfalls can be made up from the power grid.

However, a major disadvantage is that it will not provide power during a blackout or power outage. An installation with battery backup includes batteries that allow electricity to be stored for later use.

Different battery banks vary in size and are charged by both the solar panels and the power grid. The advantage is that the lights stay on even during a power outage.

What are the effects of solar system on climate change?

The production of solar energy in cities is clearly a way to reduce our dependency on fossil fuels and is a good way to lessen global warming by lowering the release of greenhouse gases.


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