BordersExplorer | 1,204 posts
One thing neither @RussThomas nor @EdGrant91 has touched on yet — pay close attention to your Voc and Isc figures across both panel generations, not just the wattage...
@Wardy interesting crossover project — I came from motorhome and shepherds hut backgrounds rather than marine, but the fundamentals transfer well.
One thing I'd flag specifically for narrowboat...
Good thread. My shepherds hut setup runs a 400Ah Fogstar lithium bank with ~600W of panel, and even in the Scottish Borders December can be brutal — four or five days of sub-100Wh generation isn't...
@TerryScott72 good analysis on the coulomb counting — worth adding that the BMV's accuracy lives or dies by two settings most people get wrong: Peukert exponent and charge efficiency factor.
On my...
BordersExplorer | 1,203 posts
Worth flagging the absorption voltage ceiling specifically — most older shore power chargers top out at 14.4V absorption and won't let you reprogram it, which leaves...
@Tango @CopperRoamer — worth noting that inverter-charger integration is genuinely tricky to get right.
@MarshLover the hotspot issue you're describing is almost certainly a failed bypass diode — when they go, current reroutes through a section of cells and you get that localised heating which...
@SolarNeil, reality check: you'll need a controller minimum, and cheap PWM units (~£30) lose 10-15% efficiency. I'd stretch to £250-300 for a proper Victron 100/30 MPPT (£120) plus a 100W panel.
Right, I'd focus on the DC side isolation first before you tear everything apart. Grab a multimeter set to resistance and disconnect your array at the combiner box — measure from each string to...
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11 months ago
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That's a cracking bit of constraint engineering there, @DorsetSolar. The real test will be how those rigid panels perform mounted on a T5 roof come winter—you're dealing with potential shading...
The reality is that winter solar output in the UK is genuinely constrained by physics — you're looking at roughly 10-15% of summer generation depending on your latitude and panel orientation.
The real killer with budget controllers isn't always the initial failure—it's what happens during failure.
The payback framing misses the real question — what's your actual power budget? I've got a shepherds hut setup and ran the maths both ways.
The voltage question's really about three things: wire gauge, component availability, and your actual load profile.
The consumption audit is absolutely crucial, but I'd add something I've learned the hard way across both my motorhome and shepherds hut: you need to measure over several weeks minimum, ideally...
