There are a lot of different factors you should be considering. This is not meant to be overwhelming but through careful considerations mentioned here, you can be self-assured that you have made a good choice
This is the first thing most people think of. A better determination would be Cost per Watt. Just because you get quoted a low price, doesn’t necessarily make it better. Always make sure that you do a Cost per Watt comparison.
You can find this by dividing the Price of Panels by Total power output.
This is pretty much common practice to have a standard warranty for PV Manufacturers. There are two types of warranties for PV Modules:
i. Performance Warranty:
Usually, this lasts for 25 to 30 years to produce at least 80% of Rated Power. Most people focus on the timescale that the warranty applies. This is just the salesperson throwing dust in your eyes. What should concern you more is the degradation rate – The rate the efficiency of the panels drops every year – This can range from 0.3 % to 0.5% usually, anything greater than this is high. Taking a degradation rate of 0.5% applied for 25 years gives you a panel efficiency of 87.5% at Standard operating conditions, considering no other losses.
ii. Workmanship Warranty
Usually, this lasts for 10 years. It protects against manufacturing Defects & other physical faults with your PV Module.
You have three components you have to worry about. In some instances, there will be guidelines/rules applied where you can only use a particular colour.
i. Panel: Monocrystalline – Black || Polycrystalline – Blue
ii. Frame: Silver || Black
iii. Backsheet: White || Black
4. Company History
To put it simply, you want to go for a company that maintains a good reputation in the market. A majority may not always be right, but when a lot of people complain or praise a certain company through their reviews, you should keep your ears open. Another parameter is how long they have been established within the industry. There is no point in having a 30-year warranty if the company goes bust before that happens.
The more efficient a PV Module, the more energy you can produce from it. This is especially important if you have a limited space to fit your panels in and your electricity demand is high. Mono-crystalline panels are more efficient than poly-crystalline panels.
I want to tie in something a bit more technical called ‘Temperature Coefficient”. It is a common misconception that PV panels are more efficient with high temperatures. The Temperature coefficient determines how much the efficiency drops for every degree above or below standard test conditions.