Do higher watt solar panels last longer, efficiency-wise? 3 installers gave me quotes with 3 different sunpower panels. The 225, 25, 20 watt panels. Whats the con and pro's of the different wattages?
If they're all from Sunpower, they're all going to be very similar. Personally, I would ask each supplier to quote with the same model of panel, and see how the prices come out. I would buy based on just dollars per watt, assuming warranty and power tolerance were the same. The lower power panels are often a better bargain, just as the slower, slightly older CPUs in computers are a bargain.
You should get the highest efficiency at the lowest price. Typically, the Sunpower brand panels have the industry best 23% efficiency depending on the model. You have to look at the specification very closely and if you don't see it, ask. There are two types of solar cells Polycrystalline and Monocrystalline. Polycrystalline cells are inferior to Monocrystalline. You will also see that different kinds of panels have different output voltages.Since you will be wiring your panels together and connecting them to either a power inverter or a charge controller (if you have battery backup), you need to make sure the panels and controller work together for maximum efficiency. Be very careful when engaging an installer especially when they are trying to sell you the equipment too. Mostly, these are not engineers and you will end up with whatever they have in stock without regard for the most optimal design.
There is no difference between them besides their rated output. One may physically fit on you roof better than another, or look better, although the physical difference between those sizes is minimal. Go with whichever installer you trust, and is preferably NABCEP certified, or working towards NABCEP certification. Get references. Don't believe just because someone is an electrician they know how to install solar electric, it's a whole different animal. Make sure they are trained in installing solar.
Power from solar panels depends upon its proper installation and the brightness of the Sun.
