1. TIER 1,2 or 3 (high, medium, low)⠀⠀⠀⠀⠀⠀⠀⠀⠀
TIER 1 panels are your big name brand panels. They are generally more expensive but run at a pretty low risk because of their long standing reputations. TIER 2 & 3 panels are both cheaper and more varied but CAN run at a higher risk if you don't understand the current manufacturing landscape. In saying that, there are cost effective options that a knowledgeable installer can help you find.⠀⠀⠀⠀⠀⠀⠀⠀⠀
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2. COMPARING WARRANTY⠀⠀⠀⠀⠀⠀⠀⠀⠀
Solar panels come with 2 warranties - a performance warranty and a manufacturers warranty. The performance warranty on nearly all solar panels is 25 years. Don't worry about this one. The manufacturers warranty on the other hand is what really matters here. It covers faulty parts, defective materials etc. You want this warranty to be AT LEAST 10 years.⠀⠀⠀⠀⠀⠀⠀⠀⠀
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3. POWER TOLERANCE⠀⠀⠀⠀⠀⠀⠀⠀⠀
Power tolerance refers to how close to the specified wattage the module will be in real-world conditions. For example, if it is a 300-watt panel and the power tolerance is +/-5%, your actual wattage could be from 285W up to 315W. These days quality panels have a “positive only” power tolerance. That means a 300W module will never be less than 300W. That’s a good thing. Our advice is: only buy a solar panel that has a “+ve only” power tolerance. ⠀⠀⠀⠀⠀⠀⠀⠀⠀
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4. EFFICIENCY COMPARISON⠀⠀⠀⠀⠀⠀⠀⠀⠀
Efficiency is not as important as most people think. As long as the module efficiency is over 15% it should be fine. More efficient panels don’t produce more electricity, they are just a little bit smaller on your roof. ⠀⠀⠀⠀⠀⠀⠀⠀⠀
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5. COMPARE TEMPERATURE COEFFICIENT ⠀⠀⠀⠀⠀⠀⠀⠀⠀
Solar panels love sunlight, but they hate heat. Their power drops as they get hotter. The temperature coefficient measures how much the power reduces for every degree rise in temperature above 25°C – panel temperature. This generally ranges from -0.4% per °C (good) to -0.5% per °C (not as good)