Mattg4321

Impressive bit of kit. Wonder if they do one for pigeons. I'm just about far enough inland that the seagulls don't visit too often, but I f*&^%^& hate pigeons. They sit in the tree and C%^P all over everything underneath (which is most of my garden as the tree is v large and the garden isn't really!)

My guess is you won’t pay elsewhere in the country currently, but I’ve not looked into it properly and the journalism is pretty poor!

You'd say an induction hob with multiple rings doesn't have multiple points of utilisation? It's a moot point really though. I have 25 years experience in this exact area, doing this sort of thing every day of the week. If someone wants to ignore my opinion, and that of the IET On Site Guide, then I don't think I'll even attempt to change their mind.

I would take a strong guess this is National Grid - DNO in the Midlands, South Wales and South West England. I can't see how anyone outside can apply it to the other DNO's, apart from the DNO's themselves. They all have slightly different rules/charges as far as I know. I've only ever really dealt with UK Power Networks as they are the DNO for anywhere within a couple of hours drive of my location.

Not true. See below in Table A2 of the On Site Guide. Yes, this is only a 'guide', but as above, I've been doing this for 25 years and have probably fitted thousands of cookers and following this formula has never yet caused me a problem and often saves my customers lots of unnecessary cost and disruption in an existing property. Correct Yes, which has a large influence on cable size. The others being installation methods, correction factors and volt drop usually. It's fairly unusual for 6mm2 not to be big enough in a domestic property. I am an electrician 😉 Diversity - On Site Guide - 18th Ed BS7671.pdf

So many people don’t take diversity into account when calculating cable sizes for cooking appliances. Add the first 10 amps to 30% of the remainder. It’s never failed me in 25 years of using this. 6mm2 is almost certainly enough unless there’s huge amounts of insulation and/or a very long run. My induction 110cm range at home is on 6mm2 and 32A RCBO when total load is over 16kW (around 70A). Don’t think I’ve ever known it to go above about 25A. Running 25mm2 is just madness. On the flip side, the amount of arguments I get into when talking about cable sizes for electric showers. People run 6mm2 when it’s very often not big enough as there is no diversity allowed. Sometimes the same guys who run in 10mm2 for a 5 ring hob, will run 6mm2 to an electric shower. Absolute muppets.

You’ll never draw that 18kW Every ‘fixed’ appliance over 2 kW should be on its own dedicated circuit really. Everything else on the ring. In practice this doesn’t usually include kettles/toasters/tumble dryers/washing machines, but does include cooking appliances. Freezer on its own dedicated circuit is a nice to have as it minimises risks of losing everything in it when a fault trips out your power.

Guessing that might be just the mounting system, without the panels?

Forgot the link https://voltaconsolar.com/products/gaia-10-degrees-rubber-self-ballasted-mounting-system-for-solar-panels-east-west?variant=52708205461838

This system claims to be only 10-11kg per sqm. No idea if it’s any good though!

Headroom not a problem if I had to lose a couple of inches. If I have to spend £600+ on structural engineer and timber etc, which is looking likely. I’ll probably bin off the idea. It just seems a shame not to use the spare MPPT, especially as I can get all the pv kit vat free still I think. And no labour costs.

No worries about intruding on a room below. The flat roof is above a utility room 80's extension with 6x2 joists (same 2.4m span) and also a garage as previously mentioned with the 4x2. There's nothing below the joists in the garage so easy access. No idea of the cost of a structural engineer for something simple like this, anyone like to guess? If it's as potentially simple as sistering the joists, I may look into it as without strengthening the joists and the costs involved in that, payback time is going to be around 2 years according to AI, so pretty attractive. Current joists go into pockets in the brickwork of the house and then overhang the wall plate on the other side by a few hundred mm to create an overhang outside. Presumably any sistered joints would just need to sit on the wall plate (not all the way to the fascia outside), but if the joists are deeper than the current ones, the bottom would need notching out at the wall plate? Assuming these would generally then be bolted to the existing joists. I'm also not sure what the approved practice would be at the junction with the house. I assume create a pocket in the brickwork for the joist to sit in.

The problem with that is that it starts to push out the payback time. I suppose it depends what strengthening work might be required. Anyone have any idea what might be typical?

I think you're right. Will be giving this a miss then.

I've got a spare MPPT on my Sunsynk inverter. I've got a garage (flat) roof on the side of my house I could fit 5 (or possibly 6, I've not bothered measuring yet!) panels on, landscape to reduce height. It's south facing, with only moderate shading early/late in the year. Half the year it will be in full sun all day. I'm sure it would payback within a couple of years or so as I can fit myself. I don't want any penetrations through my flat roof and I don't want it to look awful. Are the ballasted systems any good? Roof structure is early 70's and in good condition. 4x2 timber. 2.4m span. Not sure if I will require structural engineer? What's the lowest profile flat roof system? Do I require planning? All input appreciated!