Crofter

I can relate to that. I'm currently living on a boat, using 1150w of solar and a couple of lithium batteries. Powers all of our needs including cooking- unless we have two dull/rainy days in a row, when we have to turn the gas on. It's possible to be very frugal with energy. Cooking is far and away our biggest power user, so when we're running short we tend to switch to pressure cooker meals or stir fries which only need a few minutes cooking. And when we have enough power, we can do a big meal (tonight was pork chops and chips, done in the air fryer). I don't know how it stacks up in terms of carbon emissions, but based purely on price, I think we must be approaching break even- small bottles of gas, as used in boats, is not cheap. It's so nice to not have to buy the stuff any more.

I would look out for a suitable material and then you'll have a starting point for size, based on what's available. For robust, you won't beat solid stone of some kind. I've always used tiles because it can look great and it's cheap. Previous house I used natural slate floor tiles, it looked the bomb and cost about £10. On the next house I was advised to use porcelain 'slate effect' instead because apparently real slate can stain. I've heard that an old pool table is a good place to get slate from.

Welcome aboard! When you say off grid, do you mean no mains water/electricity/drainage/gas?

Correct. E.g. https://www.desmog.com/2023/07/20/revealed-media-blitz-against-heat-pumps-funded-by-gas-lobby-group/

For all those worrying about how the grid will cope with all those EVs, we're actually using less electricity compared to this time last year: https://www.energylivenews.com/2023/10/27/uk-electricity-consumption-plummets/

That's fairly pessimistic. Looking at the EV Database figures, if you order them by efficiency, you have to scroll through 20 pages until you get cars that are that bad. The Model 3 is listed at over 4.5mi/kWh, with more mundane offerings like the e-Corsa not far behind.

Grid demand peaked in 2002 and has fallen about 15% since then. Mostly because our household appliances have become more efficient- LED lighting is probably the biggest win there. At the moment, the extra demand from EVs and HPs isn't taking us beyond precious generation capacity, and National Grid seen pretty relaxed about the whole thing. https://www.nationalgrid.com/stories/journey-to-net-zero/electric-vehicles-myths-misconceptions

I usually grab a deep socket and drill down through the middle of it. Gives a rough guide which is usually good enough.

IME the quality of the back box makes more of a difference than the actual socket. Deeper boxes do not need longer screws. But... you can pick up longer screws for pennies on eBay. Worth having them to hand sometimes. When I was doing the kitchen, the extra depth of tiles made longer screws vital. Some faceplates are supplied with really tiny screws.

I've used all sorts of different ones, including the 99p Toolstation ones. Can't really tell any difference tbh. There are sometimes differences in the angle of the cable entry but if you have a decent service void and a bit of slack to work with you'll be fine.

That's a very good point!

Here's the thread about wow factor:

Welcome aboard. I understand the suggestion to use pros to get to wind and watertight, but you're missing out a lot of the fun. Granted, my build was tiny (50m²) but I found the basic structure to be very satisfying. Watching your plans come alive under your own hands. I was TF so it was just chop saw and nail gun, and I had the whole thing built singlehanded in a few weeks. At the framing stage, you can be pretty sloppy, the tolerances are much wider than later on. When I came to do the interior, I got nervous about messing it up. Things like kitchen worktops or skirting will show your abilities for all the world to see. I found my rate of work slowed down a lot. And some jobs seemed never ending- insulation, applying a vapour/airtight barrier inside the frame, plasterboarding a vaulted ceiling, and even just the painting, dragged on for weeks and weeks. The only bits I didn't DIY were the major groundworks (couldn't hire a big enough digger), plastering, UVC, and wiring (although I did labour for the sparky). There's a good thread on here somewhere about getting value for money 'wow' features in your build, I'll see if I can find it, it had some useful tips.

Thanks, that makes sense. For background, I currently live off grid on a boat, with 1.2kw of PV, 6.6kwhr of DIY lithium, and MPPT charge controllers. I gather in a grid tied domestic system you don't need the MPPTs, the inverter handles that? What voltage do household batteries generally work at?

Well I guess that's a no then. A set of cells and a BMS are not going to be type tested or appear on a database.

Prompted by the discussion about using an old Leaf in V2G mode, I'm wondering if it's allowable to build a battery yourself for an on-grid installation. A couple of years ago I put together a 3.3kwhr LiFePO4 battery for about £400. That was for a 12v system. A 48v system either be cheaper per kwhr because you'd only need one BMS for the 16 cells. Prices have fallen a bit since then too. Compared to an old Leaf, this is brand new cells, more appropriate cell chemistry, and it's cheaper. I accept that there may be insurance issues, but in principle are there other hurdles, e.g. do the DNO need to sign off on what you're connecting? Not that the grid would see the batteries directly, of course.

The caravan legislation dates back to 1968, I wouldn't worry about changes there! How have A&B Council handled the STL rules? It sounds like some councils are slightly taking the mick with the fees. In Highland it's no bother, it's an extra cost of about £150/yr, I'm not sure what all the fuss is about tbh. I was kind of surprised, when we started the STL business, that there was so little regulation compared to long term lets.

In Scotland at least, twin units comply- but that's not worth the hassle for a shepherd's hut. The other route to go down is hutting, which is a specific type of building in Scotland, with relaxed planning and building control rules. But the OP will have no problem calling his shepherd's hut a caravan. Is Argyll full of glamping pods? If so the planners will be very familiar with the concept of portable buildings.

The 'mobility' is inherent to the structure and not its location. You can have a suitable structure located in a courtyard or under power lines etc where no crane could ever reach it- or down the end of a narrow winding track which is cannot physically fit through. The reasoning behind this is that you could have craned it on to the site and then in the intervening years trees can grow, buildings can be added, which box in the mobile unit. It remains legally a portable building though. So on site fabrication is fine. But you do have to have a plausible way of showing that it could be lifted/moved. That means a monolithic structure, not reliant on continuous support from a concrete raft or masonry underbuilding. No dwarf walls- your joists will need to span the full width. Not a problem on a shepherd's hut. In my own case, I built a rectangular 'chassis' from heavy timber. The walls are fixed on top of it, the joists are hung within it, like the rungs of a ladder. The chassis is supported at eight locations but that's pretty arbitrary. In theory you could put slings under it, or jack it up and back a trailer underneath. Total weight of the ~10x5m building is about 10t. If you look at my early blog entries you'll see how it went together.

Yep it's pretty windy up there! At least you have Nessglaze on hand to fix you up with new windows 🙂

I would just foam them, think of all the energy you'll be saving! By the way whereabouts are you located? I lived on Lewis for about eight years so I know it fairly well.

Those sizes look a bit odd. It's generally 4", 5", or 6". Should be a snug fit between sections. Single wall is cheap and throws out a fair bit of heat. But you can't have it within a certain distance of combustibles. Twin wall can be pretty close to combustibles (~2" from memory). Non combustible includes masonry and cement fibre board. It's not rocket science but the rules are there for a reason and the consequences of getting it wrong are pretty bad.

There's lots of hype around Small Modular Reactors, but as far as I can tell they've yet to actually prove themselves. It seems a matter of faith that mass production will offset the economies of scale of larger units. Can SMRs be made to fit any site, without the need to access water sources etc? That would be a huge advantage.

I've only ever bought cheap stuff from the DIY sheds. I'm aware you can spend more but I'm not sure what you get for your money?

Ouch! Is 7 really a realistic value? Another thought- I presume I can work backwards from known energy use and use that as another data point?