Been using MPPT at the shop for a few years now.
It is a "12V in / 12V out". SB2512iX. A higher voltage input rating would be more efficient.
At the time, it cost less than adding a 50W PV (PV, mounts, wire, etc).
Something nobody seems to mention is how they make a large difference in the winter and how it helps in the real world.
- The battery bank voltage will effect the charging amps. If the battery only needs 2A to maintain float voltage then a decent MPPT will only give it 2A because it is "controlling" the bank, even if a direct connected PV array will send in 3A.
- Cold PVs make more voltage at peak power, and winter is colder.
- Less insolation in winter, and more lighting demands, and more soldering (for us), mean the battery bank is always low. The lower voltage battery combined with the higher voltage PV means the MPPT works far more efficiently.
- Here, if the system is even semi-well designed, there is far too much PV power available to bother with MPPT in summer, but winter is off the bottom of the insolation chart at <0.5H/D.
- It works best when it is needed most.
Wait to pass judgement until the bank is low, on a cold cloudless day. You will be impressed.
Increasing the PV array at the off grid shop by ~50% this week or next. Adding a 75W PV to the 180W array.
We never thought that much power would be needed, but it is nice the existing oversized MPPT can handle the increase!
G-