New no battery pure sine wave solar power system with smart switchers.

Ran a batteryless setup on the narrowboat for about three weeks last summer just to see if I'd go mad — spoiler: I did, but that was unrelated to the solar.

The smart switching side of things is genuinely where it gets interesting though. The trick is getting your loads to play nicely with what the panels are actually producing in real time, otherwise you're just asking a pure sine wave inverter to conjure power from thin air the moment a cloud rolls over Wolverhampton.

A few things worth considering if you're going down this route:

• Panel sizing — you'll want serious overkill on the array, probably 3-4x your peak load, to account for the UK's enthusiastic cloud coverage
• Inverter quality matters massively — cheap modified sine rubbish will fall over the second supply wobbles; decent Victron or similar kit handles the variability far better
• Smart switcher logic — are you rolling your own or using something off the shelf? Curious what others are using here

The honest reality living on a boat is that without a battery buffer you're essentially weather-dependent for anything more demanding than a phone charger. A tiny 100Ah Fogstar lithium acting as a micro-buffer rather than a full storage bank is a middle ground worth exploring — keeps the system "batteryless in spirit" without the drama.

Anyone actually running this long-term through a British winter? Because I suspect the data would be humbling.

@Stu1991 interesting experiment — how'd you handle the inevitable cloud cover gaps? On my boat I found even a few minutes of intermittent shading from bridges and trees would knock things out completely without a buffer.

The smart switching concept is solid in theory but I'd be curious what kit you used for it — some of the cheaper relay setups have a noticeable lag before they drop back to shore power which can be murder on sensitive electronics. Victron stuff handles it cleanly but obviously that's not "off grid 4 less" territory pricewise 😄

What were you actually running off it? Dead curious whether you managed anything beyond basic 12v loads.

@Stu1991 Three weeks batteryless on a narrowboat — so basically living dangerously every time a cloud rolled over the Midlands. That's peak British solar gambling right there.

Curious what you used for the smart switching logic. There are a few relay-based setups that'll prioritise loads by wattage, so your fridge keeps running

@Stu1991 the batteryless approach is genuinely fascinating but I'd want to see the panel data before calling it viable. The fundamental problem isn't cloud cover gaps — it's the rate of change. Panels can collapse from 90% to near zero in under a second when a cumulus edge passes over. No smart switcher I've tested reacts fast enough to protect sensitive loads without some capacitance buffer in the system.

What were you actually running during those three weeks? If it was just a 12V pump and some lighting, the maths are very different to anyone thinking they can run a compressor fridge this way.

Curious whether you had a Victron MPPT in the chain — the data logging would tell quite a story about what was actually happening to voltage during those transitions.

@Stu1991 the smart switching angle is what interests me most here. Running our static caravan off-grid, I've experimented with priority-based load shedding using a Victron Cerbo GX and some relay logic — essentially the same principle as batteryless switching, just with a buffer behind it.

The critical question nobody's asked yet: what were your minimum irradiance thresholds before the inverter would sustain continuous load? On a pure sine wave unit without storage, voltage sag under sudden load transients must have been brutal.

UK diffuse light conditions — particularly anything north of the Midlands — make batteryless genuinely marginal outside June/July. My array in Scotland would laugh at this approach for about nine months of the year.

What inverter were you actually running? The smart switcher behaviour varies enormously between manufacturers, and some handle rapid MPPT input fluctuations far better than others.