Smallholder

Sorry if I'm being a bit stupid here, but do these mounts need to be installed at the same time as the roof membrane? Or you can add them after the roof has been 100% finished?

Ahh, I love the look of those Nicholson Plates! Thank you very much for the link, will definitely look into this.

This is the layout I'm thinking about. I may be making life hard for myself in terms of wind lift, but I'd really like to use ballast rather than drilling a hundred plus holes through the roof membrane. You can see that with the existing roof and rooflights, leaving a sensible edge gap is not all that easy. Thanks for all the input folks, really appreciated.

Thank you saveasteading I'd hoped there might be some solid formula I could follow, but maybe it's just down to my own risk appetite!

I'm trying to get a new PV system installed, on a flat roof. I'm about to apply for planning permission, but can't find any solid info online about restrictions in terms of how far from the edge the panels must be. I assume this is a building regs thing rather than planning permission, but I'll need to be on the right side of both aspects I guess. Many websites seem to refer to a general rule of panels being at least a metre from the edge, which for my roof will massively reduce the area I can use. Does anyone else have any experience with this? Thanks in advance

This is the Octopus Flux tariff. As far as I know, there are not many alternatives for export. Though I may be wrong. You'd definitely need a smart meter.

VAT etc Am I missing a trick here, in terms of VAT? I understand that all kit involved in the new installation of a PV system is VAT zero rated, including batteries? So if I buy all the stuff myself, at a cost of say (very rough ballpark!) £15k inc vat, then I'm paying £2,500 in vat, that could potentially be saved and put towards an MCS registered installer doing the job. Not sure it makes any difference, but I am fortunate to have accounts with a couple of good suppliers that do panels, batteries, inverters etc. I guess there's no harm in getting a quote from an installer, and seeing how it compares to my equipment costs. There's also the point that I LOVE doing these jobs myself, and knowing how the kit works, how it went together etc. I wonder, roughly, what the export payments would be each year.

I was coming from the angle of trying to get paid to export, but if that's a no go (if we can't get MCS), then it would still be good from an environmental perspective. Even without getting any payment for feeding in, I'd be prepared to foot some additional expense in order to maximise what I feed in to the grid. Within reason.

I agree we are all kind of similar, as humans. But both my wife and I are self-employed, and we do not have any regular routine. Some days I am at home 23 hours out of 24, other times I'm not at home at all for a few days straight. There's also the point that our current consumption patterns are likely quite different to what the will be when we are generating our own power. Having been off grid at the farm for years, we have learned how to shift demand, but there is not such a great need for this at home beyond charging the EV's at night. It seems mad to design a system around a pattern that will change drastically.

Absolutely brilliant, many thanks!

Great info, thanks very much! I heard there is a bit of a faff in terms of which Victron inverters are approved for the G99 application, and from memory the bigger Quattro units are, but not sure about the larger Multiplus models. I'll have a look... Yes it looks like the largest Multiplus that's ENA approved is 5000VA (4.4kW). So in summer I'd not be able to export anywhere near as much as I'd need to.

Is that definitely the case? That Octopus would demand MCS cert? I had read online from people that had said they self installed, and were exporting to Octopus. Some of the year we would definitely be self consuming most or all of the power generated, but in the summer there should be a decent excess. Model shows over 1000kWh per month in summer, and only consuming 5-600kWh.

I have not yet gone this far with the consumption data, but I certainly could. Though our daily lifestyle is so unpredictable that I'm not sure I would get a lot from the data? I figured the battery storage almost covers a whole day of consumption, so that should set me on the right track... I'm just wondering what changes I might make to the suggested system, if I did have more detailed data? I guess I could reduce the number of panels if it somehow pointed towards that... The inverter I guess might want to change, but I'm not sure how I'd reach this conclusion. The inverter(s) I'm looking at would be a good size to ensure I could export at a sensible rate, and if needs be, charge from the grid off-peak. So I suppose the only thing I might be pointed towards, is changing the level of battery storage. Do you agree with this assessment?

I am certainly familiar with the kind of output I can expect, having relied on a 2.5kW PV system on our smallholding for the last few years. Yes I have modelled the output using this tool, so I have an idea of what to expect. It's a great tool! As I said in the post, and showed with the 3D model, this is really the max number of panels I can fit on the roof space available. I could just about get more panels on another roof, but figured there must be a law of diminishing returns that says beyond a certain point, the cost of the larger array doesn't really make sense. Plus it will cost more!