Solar Panels: A Brief Guide on choosing the right Solar Panel

A Brief Guide to choosing the right Solar Panel

A Brief Guide to choosing the right Solar Panel

Looking to buy a Solar PV equipment, but confused as to what kind of solar panels to choose.

You might be wondering:

What all do I need to consider for choosing the best solar panel?

The vendor you contacted could be giving you quotations for Solar panels he thinks is right.

But unless you have the firsthand information about solar power panels it might be difficult to make the perfect decision.

So in today’s post, I detail on the different types of Solar PV panels and the pros and cons of each type of solar panel and the different factors to consider when choosing a solar panel.

Ready?

Let’s get right in.

Photovoltaics Basics

The Solar PV system consists of solar panels made of solar cells which convert solar power into electric current. The electric current generated is DC(Direct current) which is converted to usable AC(Alternating current) power by solar inverters.

The solar cells are made by sandwiching 2 layers of silicon crystal. The top layer is N-type and is treated to lose electrons and the bottom layer is the P-type treated to receive electrons.

When the sunlight falls on the solar panel, excited electrons exit from N-type to the P-type and the P-type is ready to receive the electron into its empty spaces.

To create conductivity other elements are added for the free flow of electrons within the cell. Electrons are made to flow through a circuit to produce electricity.

A detailed explanation on the Photovoltaics can be seen in this video:

Types of Solar Panels

The solar panels differ based on the type of solar cells used. There are 3 basic types of Solar Panels

  • Monocrystalline solar panels
  • Polycrystalline solar panels
  • Thin-crystal solar panels

Monocrystalline panels

They are the most efficient at converting sunlight into electricity. They are usually dark black in color. The solar cells are made of single crystal silicon and uniform lattice structure. This homogeneous structure enables electrons to move easily and hence are more efficient compared to polycrystalline panels. Since they are highly efficient, the solar panel size is less and occupies less roof space and are less expensive.

Pros

  • Highest efficiency solar panels made of a high-grade silicon
  • Space efficient
  • Long lifespan
  • More efficient in warm weather compared to others.

Cons

  • Highly expensive

Polycrystalline panels

They are dark blue in color. The manufacturing process is very difficult. It can be done using the expensive Czochralski process which produces efficient silicon wafers or the less costly Bridgman process producing less efficient silicon wafers.

And because of its nonhomogeneous structure with many crystal fusion, there is less space for electrons to move and are less efficient. They occupy more roof space and hence less efficient.

Pros

  • Costs less
  • Lower heat resistance compared to Monocrystalline panels

Cons

  • Less efficient than Monocrystalline  
  • Less space efficiency

Thin-film panels

 These panels are often not made with silicon wafers, but made by applying a very, very thin layer of a special ‘paint’ of very fine particles of specific metals. Although the cost is low, more roof space area is required in this case.

Pros

  • Mass production – simple
  • Very Appealing
  • High temperature and shading have less impact.

Cons

  • Takes up a lot of space
  • Degrades faster compared to others

Important factors to consider:

  • Installation and venue conditions

      • The direction where the Solar Panels are installed – India located in the northern hemisphere makes true south the optimum direction to get the most out of the solar panels.
      • The tilt of the Solar panelsThe tilt of the solar panel is adjusted to make sure the sunlight strikes at 90 degrees with the panel. This angle of incidence varies with seasonal variations. The Solar output depends on Orientation, Tilt and Tracking.
      • Shading  – The solar equipment(crystalline) produces the maximum output when working without shades. Consider the different types of shading when installing the Solar PV systems. Ensure there are no obstructions creating shades on the equipment
      • Temperature – The ambient temperature plays an important role. It affects the solar panel temperature in determining the output of the solar panels.
  • Economical perspective

Consider your budget. Choose a solar panel that suits your budget when taken other factors into consideration. 

  • Cost Efficiency of Solar Panels

The efficiency of solar panels is the amount of electrical output it can provide for the amount of solar radiation falling on it per meter square. For example: consider a solar panel with efficiency 14% and area 1.5 m2. If the amount of solar radiation falling on this panel is 1000W/m2, then this panel is capable of producing

1000 * 14% * 1.5 = 210W

If this energy falls for 5 hours, then this panel will produce 210*5= 1050 Wh or 1.05kWh in a day. Higher the efficiency, higher will be the amount of energy generated per unit area. So efficiency matters if you have limited space for solar panel installation and in such a case it is better to go for higher efficiency solar panel.

Although efficiency is important what matters at the end of the day is cost efficiency, i.e. how many money you are paying for each Watt of power?

  • Solar Panel Temperature

Solar Panel Temperature plays a major influence in the output of the Solar panels.

Solar Panel temperature depends on the

  • Ambient temperature and Temperature coefficient of the Solar panels
  • Solar Panel Installation

Ambient temperature and Temperature coefficient of the Solar panels

If the weather is very hot it leads to increase in the solar panel temperature – the result is reduced output. Contrarily in cold sunny temperature, the solar panels can work more efficiently.

Information on the temperature’s effects on solar panels is provided by the manufacturers in terms of the temperature coefficient of power rating.

Temperature Coefficient

Temperature coefficient tells the rate at which the power decreases for every degree rise in temperature.

Temperature coefficient of the solar panels come in between 0 and 0.5%. Closer the value is to 0 higher the power output. Also, the installation of the Solar PV affects the Panel temperature.

All the solar panels come with 25 deg c rating. But the temperature outside can grow much higher than this.

Ex:

Let’s say a 500W monocrystalline solar panel installed on a roof is at 50degC.

The solar panel’s power loss can be calculated as follows:

50degC – 25degC = 25degC

25degC x -0.5% = 12.5%

Therefore panel power loss = 12.5% x 500W = 62.5W

Therefore panel power = 437.5W

Solar Panel installation – Where the Solar panel is installed can influence the panel temperature. If it is installed  on a rooftop the solar panels experience far greater temperature than the ambient temperature leading to decreased output.

  • Panel quality and warranty

Weather and temperature fluctuations can cause panels to degrade over time and produce less energy. Most solar panels lose about 1 percent of their power generating capacity per year.

A solar company’s product warranty is an indicator of how much a company is willing to stand behind its products. SunPower offers an industry-leading 25-year Combined Power and Product warranty. In the unlikely event that a SunPower panel is underperforming, we will repair or replace the panel and reinstall it on your home.

There are many important factors when going solar – performance, quality and warranty are at the top of the list. You also want to make sure you purchase the panels from a reputable company that will be around to back up its warranty

  • Tolerance of solar panels:

A solar panel rated at say 100 Watts should give at least 100 Watts under standard test conditions. However, if the manufacturers say that their panels have a tolerance of +/- 5%, it means the same panel can give either 105 Watts (acceptable) or even 95 Watts (not acceptable). Ensure that your solar panel will always have ‘positive tolerance’ mentioned on the datasheet.

Conclusion

The article looked at the important factors to look at before choosing the type of Solar panels that best suit you.

The important factors to consider are:

  • Your goals
  • Panel Quality and Warranty / Approvals / Certifications
  • Temperature Coefficient of solar panels
  • Efficiency of solar panels
  • Tolerance of Solar panels

If you are considering to purchase a Solar Rooftop, we could assist you in getting the right Solar Rooftop that suits your requirements. Contact us for more information.

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