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0 comparing different types of controllers:


There are a number of different types of solar controllers - the better ones are able to collect more energy
from your solar panels and charge your batteries faster.

Controllers that can "boost" are able to charge a battery from a panel that's not producing more voltage
than the battery is currently at. Most smaller arrays with fewer cells require boosting because there just
aren't enough cells to produce the needed voltage. Of course they do this by trading amps for volts.

The other type is "buck", those take a higher voltage panel and trade volts for amps instead. Some of the
better controllers can do whichever is required at the time, given the voltage your panels are producing.

The other important thing is MPPT (Maximum Power Point Tracking). When solar panels are exposed to sunlight,
the voltage they produce for a given current draw is NOT linear. This means there's a curve, and that means
there's a specific point of voltage and current that's producing the highest number of watts - that's the
"maximum power point". Good solar panels will tell you their MPP, measured in Vmp or Imp. MPP doesn't change
with sun exposure, the value is fixed for a given panel. A controller with MPPT will slowly adjust the
current draw up and down and watch the voltage and current change, and settle at the current draw that
maximizes watts delivered to the battery. Depending on the battery's condition, this may not be at the
panel's marked Vmp since the battery also has a preferred power point, which DOES vary depending on how
charged it is. And a battery is going to have a limit to how fast it can be charged, as well as slowing down
the acceptance of power as it approaches fully charged. MPPT controllers take care of all of this for you.

Chargers that don't have MPPT are often marketed as "PWM" which can only convert down, but the process is not
as efficient as bucking, so you lose even more power in the conversion. You can think of the difference
like MPPT is using a transmission and shifting gears to keep fuel economy high, where as PWM is just leaving
it in 2nd gear, regardless of how fast you need to drive.

Besides converting solar energy for use and charge, most controllers will have two outputs - one for the
battery and one for the load. If the battery is fully charged, it will disconnect the solar, to avoid
over-charging the battery. If the battery voltage gets critically low, it will turn off the load to
prevent the battery from deep-discharging. Most will also disconnect the load if the battery voltage gets
too high. If you don't need these features, you can just connect your loads directly to your battery.

Some controllers let you adjust these voltages. Most of the cheaper controllers are only designed to
work on one battery voltage - like 12v or 24v. Most of the higher end controllers automatically adjust to
the battery you connect.




last updated 11/30/2023 at 20:12:23