DIY Off-Grid Solar Project

Just finished wiring up my shepherd's hut setup last month so this is fresh in my mind!

Running a 200Ah Fogstar Drift LiFePO4 with two 200W Renogy panels on the roof. Went with a Victron SmartSolar MPPT controller and honestly the Victron app alone makes it worth the premium — being able to see exactly what's going in and out in real time is dead useful.

Few things I wish I'd sorted earlier:

• Cable sizing — I undersized my first run and lost way more to resistance than expected
• Fusing every connection — seemed overkill at first, not any more
• Shading — even partial shade from a nearby tree killed my output more than I anticipated

The hut is mostly used weekends so the battery rarely gets fully depleted, which suits LiFePO4 chemistry well apparently. Running lights, a small 12V compressor fridge and charging devices no problem.

What's everyone else using for monitoring? I'm eyeing up a Victron Cerbo GX but hard to justify the cost for a weekend setup tbh. Anyone gone down that route for something similar or is the SmartSolar bluetooth enough?

Also curious what others are doing for winter — panels are a bit marginal November through February even in the south. Thinking about adding a third panel but roof space is tight.

@AnneWatson that's a solid little setup for a shepherd's hut! I'm curious what capacity MPPT controller you went with for those two 200W panels — did you leave yourself any headroom for expanding the array later?

Also wondering how the Fogstar Drift is holding up in colder temperatures? I've got a 100Ah Fogstar myself and noticed the BMS cuts out more aggressively below about 5°C when charging. Not a massive issue in summer but I'm a bit concerned heading into winter months.

Did you end up needing a separate DC-DC charger or are you running purely off solar? And what's your typical daily consumption looking like — are the 400W of panels keeping up comfortably or finding yourself a bit short on cloudy days?

@AnneWatson really interested in the Fogstar Drift choice — been eyeing those up myself for the motorhome. How are you finding the cycle performance so far?

Also following on from @George1972's question, with two 200W panels you'd want to check your Voc in cold conditions before settling on an MPPT size. Two Renogy 200W panels in series could push close to 50V open circuit on a cold morning — worth confirming your controller's input voltage rating covers that headroom.

What's your panel wiring config — series or parallel? That'll affect which Victron SmartSolar model makes most sense. The 100/30 is popular for smaller builds but series wiring might push you toward the 150/35.

@AnneWatson nice one. Fogstar Drift is decent bang for money — got the same cells in my narrowboat and they've been solid for 18 months now.

One thing worth keeping an eye on: Victron's absorption settings out the box aren't always dialled in perfectly for LiFePO4. Worth double-checking your charge profile in VictronConnect matches Fogstar's recommended voltages. Easy to miss and it matters long-term.

Also curious what your shading situation is like — two panels in series vs parallel makes a big difference on a shepherd's hut roof where you might get morning shadow from the eaves.

Great setup @AnneWatson! One thing worth mentioning that I don't think anyone's touched on yet — with a shepherd's hut you'll want to keep an eye on ventilation around the battery if it's tucked away in a cupboard or under a bench. LiFePO4 is far safer than lithium-ion but they still don't love being completely sealed in with no airflow, especially in summer when the hut heats up. Fogstar recommend keeping them below 45°C during charging.

Also curious whether you've got any heating load planned for winter? A small 12V diesel heater can absolutely hammer a 200Ah bank on cold nights — worth factoring in if you're planning year-round use. What's your typical daily consumption looking like at the moment?