SeanK

Would love to know how you're getting on with this! Had always thought diversion units had to have grid connection, but after a search seems that's not so! Some off the shelf alternatives: An Australian unit - https://www.ecocool.com.au/products/hot-water/plasmatronics-jackal-hot-water-system-power-diverter/ And one in the UK that apparently works off-grid - https://www.earthwiseproducts.co.uk/solic-200/ Just finding out if these units can work in multiples....

...kw instead of kW?

Seems like they plucked the number out of the air right?

I was imagining coils like these might do the job but I'm likely being naive... but you're right, upon further googling it seems there are pre-plumbed thermal stores available for around a grand.

Another couple of products from Poland that do this job, any folk experience with these? https://actii.pl/en/ladowarki-prostowniki/979-mpm-pwm-heater-charging-controller-for-solar-solar-panels-actii-ac7391-6931240073919.html?SubmitCurrency=1&id_currency=4 https://ekopulsar.pl/news/sterownik-fotowoltaiczny-PulsarSimple On a separate note, keen to hear any thoughts on DIY thermal stores. These tanks are suitable for hot water and a fraction of a price, is there anything in the regs that doesn't permit this approach? https://www.draytontank.co.uk/product_details_388.htm

Thanks for the heads up and the link @ProDave! We survive without a telly just now. You never know, might get a wee inverter to have on hand just in case... Just having a quick look through the blog, great stuff there.

Thanks SteamyTea, plenty to mull over! A small turbine ticking over straight into a thermal store sounds sensible. I'm put off slightly by the high outlay of a turbine and inevitable mechanical problems posed by fast spinny things! A D400 seems a good contender though. We could meet our winter hot water/cooking/space heating needs with wood and peat (we'll have a peat bank). I've plans for a wood fired cook stove and water boiler and a HETAS installer to build them. I have been wondering whether PV could be dumped into the thermal mass of these heaters in summer... Sorry, should have given a bit more context! No mains connection, looking for a simple domestic system for off grid. The folk at Living Energy Farm have lived with their setup for over ten years and to me, it makes a lot of sense. Interestingly, as laid out by Scottish Building Control - a conventional supply doesn't seem to be required where no mains is available. Obviously there are risks, good practices and it is worthwhile having an electrician okay it - but a 120V DC is considered extra low voltage and doesn't require a building warrant. Forgoing AC and a lot of standard appliances is something we would be fine with.

Good points, thanks SteamyTea. I'm coming at it from the ethos/approach taken at http://livingenergyfarm.org/energy/ - seeing if it's feasible to do away with inverters and such like. Is the problem you highlight exclusive to DC (or only able to be addressed in an AC system)? Living Energy Farm actually use Solar Thermal with a little pump run by PV. Not sure how effective this would be in the Outer Hebrides and the idea of (perhaps) simplifying matters by eliminating the plumbing involved with Solar Thermal appeals. Don't know a great deal about Solar Thermal but I wouldn't have thought they would be able to get a thermal store up to temperature...

This will no doubt raise more questions that it answers but - been looking into DC micro-grids, inspired by the unconventional use of PV, Nife batteries and "Daylight Drive" employed by these guys - http://livingenergyfarm.org/energy/ In line with their approach of being "multi linear" - I've been pondering standalone PV/hot water and PV/cooking systems for the summer so we're not relying on firewood or peat.

I've been pondering an off-grid standalone PV setup for dumping DC straight into a thermal store, to be supplemented with a wood stove in winter months... the simplicity of the system appeals and I wondered if anyone here has put together anything similar? Seems some folk try and match the panels to the heater resistance - but as this figure varies there are a few products implementing MPPT to increase efficiency. One Austrian made and a few in South Africa: https://zerohomebills.com/product/mypv-dc-elwa-solar-pv-water-heater/ https://www.sustainable.co.za/solarhotty-pv-water-heater-controller.html https://www.sustainable.co.za/geyserwise-offgrid-pv-solar-water-heating-kit.html The "Geyserwise" products use PTC elements which are very interesting, and seemingly inherently safe... I've a distributor for SunAmp who is enquiring about their "dPV" units that might be a worth a look at for this purpose... (if any still exist).