Anyone else running a Renogy MPPT on a static with mixed panel orientations?

Got a bit of a head-scratcher on my setup. Running a Renogy Rover 40A MPPT on the static and I've got 4x 200W panels — two facing due south on the roof and two on a ground mount that's more southeast. They're wired into two separate strings going into the same controller.

The southeast pair seem to drag the whole array down on morning generation, which I expected, but I'm seeing some odd voltage drops mid-afternoon too when the south panels should be smashing it. Wondering if I'm losing more than I should by mixing orientations on a single MPPT rather than running a second controller for each string.

Currently feeding a 200Ah Fogstar Drift lithium, so efficiency actually matters — don't want to be throwing watts away needlessly. Has anyone split this into two MPPTs and actually measured the difference, or is it not worth the cost of a second Victron 100/30?

@BurnGlen been down this exact rabbit hole with my boat setup before moving to separating the strings entirely.

The core problem is your Rover is hunting for a single peak across panels that have different peaks at any given moment. Southeast panels will be pulling ahead in the morning, south panels dominate midday — the controller just can't satisfy both simultaneously.

Worth considering splitting them onto separate controllers. Fogstar's budget MPPT range is decent if cost is the concern, or a second Rover wouldn't break the bank secondhand.

Alternatively, if rewiring isn't appealing, put your south-facing pair in series and southeast in series, then parallel the strings — at least the voltage characteristics stay consistent even if the current mismatch costs you a bit.

What's your actual harvest looking like currently? That'll tell you how badly the mismatch is biting.

DodgyRigger | 847 posts | ⭐ Trusted Member

@BurnGlen mate, the thing to watch here is whether you've got those mixed orientation panels wired into the same string. If you have, your south-facing panels will be dragged down to match the southeast ones whenever there's a mismatch — kills your morning production something rotten.

Best fix I found on a similar setup was splitting them into two separate strings feeding the Rover's single input in parallel, keeping voltages matched but letting each pair do its own thing current-wise. Just make sure your combined Voc stays within the controller's 100V input limit before you wire anything up.

What's your current wiring arrangement? If they're already parallel rather than series that changes things a fair bit.

Hey @BurnGlen, classic mixed orientation headache! The Rover 40A has a single MPP tracker, so it'll compromise between the two strings rather than optimising each independently. If your south and southeast panels are wired in parallel, the southeast ones will drag down performance of the south-facing pair during morning hours particularly.

Worth considering splitting them across two separate controllers if you can stretch the budget — even a modest second MPPT would likely recover enough lost generation to pay for itself. Alternatively, wire them in separate strings and connect to the controller's input, but honestly with differing orientations you're still leaving efficiency on the table.

What's your current wiring arrangement — series, parallel, or a combination? That'll make a big difference to how badly the mismatch is actually affecting you day-to-day.

@BurnGlen your south panels and your southeast panels are basically having a constant argument about who's working harder, and your poor Rover 40A is stuck in the middle like a referee at a particularly rubbish football match ⚽

The single MPPT tracker will just pick a voltage that's least bad for both strings — you're essentially leaving watts on