Solarladeregler 100/30

Bit of a tangent from the main thread topic but this feels like the right place to post — anyone else find that installers (or even just the bloke who helped you on a Saturday) just bung in a Victron MPPT and leave everything on factory defaults?

I've got the SmartSolar 100/30 on my garden office setup, paired with a Fogstar Drift 100Ah LiFePO4, and when I first got it running I assumed the defaults would be "good enough." They absolutely were not. The preset charge profiles are very much aimed at lead-acid, and even the lithium preset isn't quite right for every cell chemistry.

Worth checking a few things straight away:

• Absorption voltage — for LiFePO4 typically wants to be around 14.2–14.4V, not the 14.7V lead-acid default
• Float voltage — I run mine at 13.5V, some folk go lower
• Tail current — often overlooked but crucial for not hammering your cells near the top of charge
• Max charge current — the 100/30 can push 30A but whether your battery wants 30A is a different question entirely

The VictronConnect app via Bluetooth makes all this dead easy to tweak, no laptop needed. Connect your phone, go into the battery settings, and spend 20 minutes actually reading what each parameter does. The Victron docs are genuinely decent and there's a specific LiFePO4 setup guide on their website.

Would be curious what battery others are pairing with the 100/30 and what charge settings you've landed on — always feel like I'm one firmware update away from needing to revisit mine. 🔧

@WheresMeWires yes, absolutely this. Had a "helpful" neighbour spec out my boat install last spring and he just defaulted to a Victron MPPT 100/30 without even asking about my panel configuration or battery chemistry. Turned out I had a 24V LiFePO4 bank (Fogstar cells) and the panel string he suggested would've been completely wrong for it.

Nothing against Victron — brilliant kit — but there's a tendency to treat it like a universal answer before anyone's done the maths.

Has anyone found a decent UK-focused sizing calculator that actually walks you through the questions properly? I've been pointing people toward the Victron MPPT calculator but even that assumes you already know what you're doing to some degree.

@NicolaTaylor72 the boat scenario is classic — marine installs especially seem to attract the "just bung in a 100/30 and call it done" mentality. My garden office setup had exactly this problem initially; someone quoted me a 100/30 for a 180W panel array which is frankly hilarious overkill on the current side but simultaneously wrong on the voltage side once I looked at my panel Voc properly.

The 100/30 is a brilliant bit of kit but it's not a universal answer — Victron's own MPPT calculator will tell you that in about 30 seconds. Worth noting the 75/15 or even a 100/20 suits most modest residential setups perfectly well, and at meaningfully lower cost. The "100" in the model name refers to max PV voltage, not some quality tier, which I suspect half the Saturday installers don't actually realise.

Great points all round. The thing is, the 100/30 is a cracking bit of kit when it's the right tool for the job — but I've seen it dropped into systems where a 75/15 would've done the job perfectly and cost half as much. The other side of the coin though is people going too small to save a tenner and then throttling their array. Worth actually sitting down with the numbers before you buy anything. @WheresMeWires — what's the actual panel setup you're working with? Knowing your Voc and expected current would tell you pretty quickly whether the 100/30 is justified or overkill. There's a decent sizing tool on the Victron site that takes about two minutes to run through. Sometimes the "obvious" choice turns out to be right, just not always for the reasons people assume.

@DailyLife hits the nail on the head there. The 100/30 is genuinely excellent kit, but I think part of the problem is that Victron's reputation has become almost a shortcut for "job done properly" — and that's not always fair on the customer. I've seen setups where a decent PWM controller would've served just as well for a fraction of the cost, and the extra money could've gone into better battery capacity instead. Worth asking why it's being specified every time. Is it genuinely the best fit, or is it just what the installer has on the shelf and knows inside out? Nothing wrong with familiarity, but it shouldn't come at the buyer's expense.