MPPT stands for Maximum Power Point Tracking. It is a type of solar regulators and provides higher efficiency of transferring your solar energy to your battery.
So why it provides higher efficiency?
If you are not sure how regulator works and why we need them for our solar system, please refer to this article: What are solar regulators?
The standard regulator will only draw power from the panel at the nominal charging voltage at the same amp that the panel is putting out. For example, you have a 120w 12v solar panel, the maximum amp rating is 6.7A and the optimum power voltage is 17.85V. 6.7×17.85=120w which makes perfect sense. But a standard regulator will drop 17.85v to 14v (which is the charging voltage) and keeps the amp the same. In this case you are basically getting 14×6.7=94W out of the panel and the other 26w will be lost. The efficiency of the system is only 94/120=78%.
Instead, a MPPT regulator will takes that 17.85v and 6.7amp from your battery and convert them into the ideal charging voltage with a higher amp. A very small percentage of energy will be lost during this converting process but the over all system efficiency is still higher than 97%. If the charging voltage of your battery is 14v, 17.85×6.7=120w, (120w/14v)x97%=8.31amp. Now you are having 8.31amp instead of 6.7amp pumping to your battery.
Another great feature about MPPT regulator is that the system voltage doesn’t have to match. The solar panels can be 48v and the MPPT will drop it down to 12~14v to charge your 12v battery as long as the regulator is configured properly.
Winter, and/or cloudy or hazy days – when the extra power is needed the most.
- Cold weather – solar panels work better at cold temperatures, but without a MPPT you are losing most of that. Cold weather is most likely in winter – the time when sun hours are low and you need the power to recharge batteries the most.
- Low battery charge – the lower the state of charge in your battery, the more current a MPPT puts into them – another time when the extra power is needed the most. You can have both of these conditions at the same time.
- Long wire runs – If you are charging a 12 volt battery, and your panels are 100 feet away, the voltage drop and power loss can be considerable unless you use very large wire. That can be very expensive. But if you have four 12 volt panels wired in series for 48 volts, the power loss is much less, and the controller will convert that high voltage to 12 volts at the battery. That also means that if you have a high voltage panel setup feeding the controller, you can use much smaller wire.