How to evaluate if your site is good for solar?

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Much before anyone installs a solar energy system, the first question that crosses everyone's mind is, "Do I have a good site for solar? How do I evaluate the basics?" Most solar installers provide site assessment before installation, but frankly an initial basic assessment is not exactly rocket science. And although solar electricity costs today are almost at parity with those being supplied by most utility grids, unsuitable sites and bad installations are the top reasons why solar installations sometimes don't live up to performance expectations.

So, we thought why not put out a post to discuss prerequisites that go into making a site a "good solar site" and also discuss few other factors that may help in your initial evaluation.

Although designing the solar energy system itself requires expertise, but a good solar site by evaluating a few basic factors namely: Type of installation, Orientation, Tilt and Shading. In this post, we primarily are discussing solar energy systems where the panels are fixed (majority of installations are fixed panel installations). It is possible to install solar panels on trackers where the panel tilt and direction can be changed as needed. But evaluating sites for those kind of systems is a subject for another post. Let us look at the evaluation criteria in detail.


Type of Installation

This refers to whether your are looking to install the system on ground or is it going to be a rooftop installation. If it is a ground or flat roof-top installation and you have a reasonably sized space then you don't need to evaluate the next two factors: orientation and tilt of the site. It is generally only for inclined rooftop installations that you would need to consider these.


Orientation

“Orientation” simply means the direction your solar system will end up facing (i.e. north, south, east, west). While panels facing south are best but panels installed facing east or west still generate a very high percentage of possible power. North-facing systems are generally not recommended. India is located in the northern hemisphere, closer to the equator between latitude 6˚ and 36˚N (the longitude boundaries are 68˚ and 98˚E). In order to get the most from solar panels, they must point in the direction that captures most sunshine. And since India lies in the northern hemisphere, solar panels should face southwards for maximum efficiency.

Since, for most inclined roof installations the panels are installed flat against the roof, the direction of the roof ends up determining the direction of the panels. So, we recommend to make a note of your roof direction.


Tilt

The “tilt” implies the angle between the solar modules and the ground. Solar modules at a tilt of 0 degrees would be flat i.e. horizontal while a module at 90 degrees would be vertical. The sun’s path changes throughout the year and modules produce the most electricity when sun’s rays hit perpendicular to panel surface. Hence, it is best to have modules tilted at an angle which helps maximize the amount of time the rays of sunlight are close to perpendicular to the panel.

If the solar panels are going to be fixed throughout the year and you want maximum overall production, the solar panel tilt angle should be more or less equal to your latitude. So that the panels can intercept maximum solar radiation during the year. As mentioned before, for most inclined roof installations the panels are installed flat against the roof, so the tilt of the roof ends up determining the panel tilt as well.


Shading

Shading is one of the most critical factors that may limit the  energy production by your solar energy system. While evaluating, do check if your potential solar site is completely without shade from trees, chimneys, surrounding buildings, etc. If you feel the installation site is not free of shading, it is important to do a shade analysis of any potential solar site since it can be surprising what ends up being shaded at different times of the year. Generally speaking, life of a solar system spans approximately twenty to twenty five years and hence it is important to think ahead. What if those trees that are currently twenty feet tall are at forty feet in next few years?

Let us say that if your solar array is shaded by twenty five percent, then you can expect your output to go down by as much as seventy five percent. Although there are ways to mitigate effects of shading on energy production it is best to chose sites free of shading.


A Few Other Factors

If your home or property has passed the orientation, tilt, and shade tests, following are few other factors that you may want to consider:

  • Roof Age and Material
  • Electrical Service and Utility connections
  • Amount of space available for installation

You may want to find answers to following questions:

  1. How old is your roof and what type of a roof is it? 
  2. Will you need to replace your roof in the near future or did you recently get a new roof?
  3. Do you have enough space for solar panels and also battery system (if needed)?

If you have recently got a new roof within the past five years, then the age of roof will probably not be a concern for you. But if you are going to be replacing your roof then it will be good to install your solar system during the same time period.

Many states in India have authorized and adapted to the policy of Net Metering which is nothing but selling back excess energy that you produce back to the grid and the solar system is a grid connected system. Hence, you may want to check with your service provider of necessary requirement for such a setup, understanding wiring and getting state electricity board's approval to get yourself connected to the grid. 

A solar professional will be able to determine all of this for you and should also be able to fill out any paperwork required by your utility for interconnection. At EnerMark, we evaluate projects based on financial returns for the life of a system, so we take care of all these details for you.

Once you have thought about and have information about the evaluation factors listed above, we can provide detailed information about costs associated with your solar system and return on investment, in a few minutes online. Just go to project estimator and create a report for your site with all the necessary details. In fact, the Enermark estimator uses the same industry leading software used by top installers to evaluate sites.

This is it for now, would love reading your comments. If you have a question related to site evaluation or for that matter any topic related to energy under the sun (pun intended), do check out our online community





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