Looking for solar panel recommendations

Interesting setup — I'm in a similar situation trying to expand my solar array on the boat and could do with some input too.

Currently running a Victron SmartSolar MPPT 150/35 with a couple of older 200W panels that came with the vessel. They're functional but I suspect I'm leaving a fair bit of generation on the table, especially on the grey days we get so much of here.

A few things I'm genuinely unsure about:

• Mono PERC vs half-cut cells — is the real-world difference on overcast UK days actually worth the price premium?
• Rigid vs flexible — I know flexible panels cop a lot of criticism for longevity but space constraints on a boat make them tempting
• Brand reliability — I've seen Renogy mentioned a lot, but also some UK suppliers pushing their own-brand panels. Anyone had long-term experience with either?

My array feeds into a 48V LiFePO4 bank (Fogstar Drift cells), so getting the voltage configuration right with the MPPT matters. I'd rather not fry anything expensive figuring it out.

For anyone running a similar Victron ecosystem — what panels did you end up pairing with yours, and did you go for a series or parallel string? Roof space is tight so I'm trying to maximise output without overloading the controller's input limits.

Would be good to hear what's actually worked in practice rather than just what looks good on a spec sheet. UK conditions are a different beast to the sunny climates most of these panels seem to be marketed towards.

@Taffy the 150/35 is a solid controller, should handle a decent expansion without needing an upgrade depending on what panels you're adding.

Few things worth checking first:

• VOC in cold conditions — panels spike voltage when it's cold, easy to accidentally exceed that 150V limit on a winter morning
• String configuration matters loads on a boat, shading from rigging etc can kill output

For panels I've been happy with Renogy mono panels for the price point. Used a couple on my garden office setup. Victron branded panels are quality but you pay for the name obv.

What's your current string voltage sitting at? Might be worth running the numbers through Victron's MPPT calculator before committing to anything — saves a headache later.

@Taffy worth noting that the 150/35 has a 35A output limit, so your maximum usable charge current into the battery bank is capped there regardless of how many panels you throw at it. At 12V that's only ~420W effective — at 24V you double that to ~840W, which is far more sensible for a boat expansion.

If you're staying 12V, you're already approaching that ceiling with modest panels. I'd seriously consider whether a second MPPT (perhaps a 100/20 on a dedicated domestic circuit) makes more sense than simply daisy-chaining more panels onto the existing controller.

Fogstar do decent value panels that I've run successfully on my narrowboat without complaint. What's your current panel wattage and system voltage? That'll determine whether the 150/35 has meaningful headroom left.

@DefenderAdventure already covered the 35A ceiling so I'll just add — if you're going series strings to keep current down, just double-check your Voc doesn't creep over that 150V limit on a cold morning or your Victron will have a very expensive lie-in.

@SolarKeith has basically turned this into a masterclass, so I'll just chip in with the bit nobody's mentioned yet — panel orientation matters more than people think, especially on a boat where you can't always guarantee a southerly aspect.

I run a couple of 200W Renogy monos on my static van tilted at about 35°, and the