Anyone actually running a garden office on a tight budget solar setup?

Been powering my garden office for about 8 months now on a pretty barebones system — 200W of Renogy panels, a 30A PWM controller (yeah I know, MPPT next time), and a single 100Ah Fogstar Drift LiFePO4. Total spend was around £450 all in.

Runs a laptop, a couple of LED strips, phone charging, and a small USB fan in summer no bother. Winter's been rougher — short days plus a north-facing fence means I'm sometimes dipping below 20% SoC by 3pm. Had to run an extension lead from the house twice in January, which felt like defeat tbh.

Thinking about adding a second 100Ah Fogstar to the battery bank rather than upgrading the panels first. Anyone done similar? Wondering if more storage actually helps in winter or if the problem is just not enough harvest in the first place — i.e. I'm emptying what little I collect almost immediately anyway.

KeithMartin | 203 posts

@WrongFuse96 solid little setup that, and 8 months is proper real-world data rather than just forum theory! The Fogstar Drift is a cracking battery for the money — good shout there.

One thing worth knowing with that single 100Ah: LiFePO4 really doesn't like sitting at 100% state of charge for extended periods if you're not drawing much. Worth setting your absorption voltage slightly lower if your PWM controller allows it, maybe around 13.8-14.0V rather than the full 14.6V. Extends cycle life noticeably.

What's your typical daily load like? Running monitors, lighting, that sort of thing? Might be worth logging your actual consumption — even a cheap plug-in energy monitor on each device tells you a lot about where your budget should go next.

Tommo30 | 147 posts

@WrongFuse96 nice one, that Fogstar Drift is a cracking bit of kit for the money. Curious what your actual loads are day-to-day? I've got a similar-ish setup on my shed office — 320W panels with a Victron MPPT (splashed out eventually, worth every penny) and two 100Ah LiFePOs in parallel. The upgrade that genuinely surprised me was switching to a decent low-draw monitor — old TN panel was pulling nearly 40W, new IPS job does the same work at 22W. Those small wins really add up when you're working with limited capacity. How are you finding winter so far? That single 100Ah must be getting a bit stretched on the shorter days if you're doing full working hours.

BerlingoLife | 412 posts

Running something similar on the narrowboat so comparable constraints — limited roof space, weight matters, budget matters.

One thing nobody's mentioned yet: your PWM controller is losing you a fair chunk of that 200W depending on panel voltage. If your panels are wired for 24V nominal into a 12V system you're essentially throwing away a third of your generation capacity before it even hits the battery.

Might be worth checking your actual panel config and what the controller's seeing. A second-hand Victron SmartSolar 75/15 off eBay can be had for under £40 sometimes — genuinely transformative difference on the same panels.

Also curious what your worst-case winter days looked like. November/December on a boat was pretty grim for me even with MPPT, so knowing how the Drift handled repeated partial cycles would be useful.