So you’ve bought $3K worth of solar panels and the salesperson now wants to sell you a charge controller worth about $100 to monitor the battery state and prevent overcharging of the battery by the solar panels.
Now they tell you that their controller is 30Amps. Would you question it? Nope. YOU TRUST THEM! He or she goes about installing your system and yet each time you are in full sunlight, the controller “pops” a fuse. To remove it, you have to gain access to the controller’s back circuit (if it’s not auto-reset). Now why would it act like this if indeed it was the right unit for your needs?
Well, check the controller’s specifications. Did the manufacturer write “30AMPS for 60 seconds” in small print? So what is the true rating of this controller? Likely about 21Amps.
Now if the controller should be able to handle 21Amps (about 300W) why is it that when the panels are not in full sunlight, the controller still pops? Once again, truth in advertising would force any knowledgeable vendor to tell you that you need a buffer between the rating of the controller (at its CONSTANT maximum rating) and the total power of the solar panels.
OK, now let’s throw in one more tidbit just for fun…the controller he has sold you is not PWM based, which is just a fancy way of talking about monitoring and pulsing the charge to the battery so that it gets maximum power. A battery is like a sponge my buddy Randy once taught me. You can blast water into a sponge for the first 90% but for the last 10% you need to stage it in otherwise the water (aka power) will just bounce back. So basically, if your controller is not PWM based, then you could be losing 10% of the value of your solar panels. Take that $3K you just invested in solar panels, and write off $300. Tough luck!
This is the prime reason that during the past season, my company, ICP Solar, has been talking to industry leaders and technology developers. We have gauged the wishes of the consumers and compared our old offerings to new ones. So we partnered with a German firm over the summer and will be offering ONLY PWM controllers under our new brand..set to launch next month. You won’t see them on our website until the official launch though, so please be patient. In the meantime, there are other companies from whom you could buy a very legitimate and high grade PWM controller like Morningstar or Specialty Concepts.
Therefore, if you are being offered a non-PWM controller, stop and think about how much the salesperson really knows about solar. Mass merchants may drive volume, but eventually you need help to understand such complicated systems. And if their salespeople have not been trained properly, then more often than not, you will get wrong advice. To buy a non-PWM controller for up to 5Amps is perhaps OK (your total loss would be $50). But lose $300, what a shame that would be…
Sass