jimseng

Actually, re reading the manual I'm still trying to get my head around how to set an export limit, but I am getting there. Luckily I don't have kids. I'm not convinced I will let any into my new house. They are noisy, sticky things that leave jam and muddy footprints everywhere.

Not sure I fully understood this. Can you expand? When I briefly looked through the manual today it seemed you can set the export to any KW value, but it was a fairly cursory browse through. I'm talking about the Sunsynk 10 / 12k inverter. If I do want to try and export at some point Then it likely going to have to be the 2k limit under a G100 application with anything other than a G98 certified inverter.

Exactly. A 10kw Sunsynk and a 16kWh Fogstar battery is around £3.5k all in. That is a G100 / 2 compliant system. With the 60 amp pass through I think I would struggle to max it out, unless I really try.

Maybe. I'm a bit of a stickler for rules in case it comes back to bite me. If I got investigated it might become tricky. I'm open to all suggestions though. I will be using the grid power too, otherwise I would fit a battery charger and not connect the inverter to the grid at all, that would mean I wouldn't need to involve the DNO. I have thought about that route but I think it would be a bit limiting in the winter. I must admit I haven't done the maths yet as I'm not sure how much battery power I will start with.

That isn't how I understand it. My understanding is that to even fit an inverter that is capable of > 3.6k export, even if it is set to export nothing requires a G100 application and maybe even a witness and password to prevent the settings from being changed. Or a G100 limiting device between the meter and the inverter (costly from what I have found). If I am wrong then that would simplify everything. If there is an inverter that is incapable of exporting to the grid then I expect that would work. There is a Victron option of a 5Kw set to 3.6kw in firmware from the supplier, and therefore G98, but it then effectively becomes a 3.6kw inverter, all be it with a higher grid pass through, which, to me, seems pointless.

Do you mean there was a fee to Octopus to allow you to get paid for a non MCS approved install? The whole energy supplier side of things is another bit of research I have to do as I don't even have a DNO connection yet. Sometime in the new year.

That is a question I have mused over. Passing the ac output of the G98 device to the ac input of a slave device set to zero export. Or a generator input. But in order to live with the system, a high ac passthrough is important to me. I don't want to split my loads into on and off grid if I can help it. That is why I am looking at a 10kw system for an all electric house. 3.6kw isn't enough for my long term ambitions. I should add that grid export is not relevant to me as it is a a self install. Off peak battery charging and lots of battery capacity is important.

You're right. There reason I asked the question is, first, I was feeling grumpy at the notion that we are supposed to be moving towards net zero and yet [insert political point about Britain, privatisation, consumers trying their hardest to do their bit by investing in energy efficient homes and still having to contribute their own limited finances towards the under invested national infrastructure], so I was thinking about ways round it. And the second is that actually, it is quite hard to find a hybrid inverter that ticks the G100 box and is compatible with 52v batteries (for instance, the three you mention above are all incompatible). I had struggled for a while to find anything that fitted my criteria (cross referencing the ENA database with datasheets can be a bit bewildering for a newbie like me). But I think I have found two candidates now, A Growatt and Sunsynk. I think I am favouring the Sunsynk at the moment simply due to the AC passthrough current, but they are a little bit more expensive. I did ask the DNO how the 2k limit fitted in with a G98 application. His response was: "The rules get a little complicated you are correct under G98 you can install up to 3.68kW per phase on a fit and inform basis, once you get into G99 things change NGED can restrict exportation to limits that don’t have an adverse effect to the network so effectively the 3.68kW rules does not necessarily apply." Part of me wants to do a G98 application and see if they are forced to upgrade. I am actually writing a letter of grumpiness to Ed Milliband, but I doubt he'll even read it.

Thanks JohnMo. Simple is indeed best. I'll take a look at your suggestion.

I have been struggling to find one that suits my battery choice. I have been on the ENA database and for some reason I am having difficulty. I don't know if I am using the wrong search terms. I found a Growatt that seemed like a good fit but I can't track down a G100 certificate and the Growatt UK distributor neither answers the phone or responds to emails so far. It is proving harder than I thought it would be. It seems the G100 part of manufacturers literature is a low priority so they don't advertise it much.

I was actually asking if bypassing the whole G100 limitation, and the costs involved, by keeping the inverter off grid is a good idea. I am installing 10.2k of solar and planning on as much battery storage as I can afford. To me, being able to choose whether to run things like the cooker, immersion, heat pump off the grid or off battery/solar gives me more choice. 4 pole contactors seem fairly cheap in the grand scheme of things, and easy to control. But the main thing is my pathetic G100 export limit. If I can avoid jumping through that hoop that is a win for me. I assume I don't even need to mention anything to the DNO?

Ok. Thanks. So here goes... good idea or bad idea? (Runs for cover).

Hello. Here is a simple question, Given that I am limited to 2kw export and G100 application if I go down the grid tied inverter route. Is there any legal issue with keeping the inverter purely off grid and using a 4 pole changeover contactor to switch some loads to grid if needed. The inverter would not then be connected to the grid at all. Do I even need to tell the DNO what I am doing? I'm only interested in the legal side of things, if we can keep strictly to the question. Whether it is a good idea or not is for a different thread perhaps?

That does seem the best solution. The Growatt I mentioned above seems to fit the bill. I have no idea if they are a good make but on paper it works.

I have found the Growatt SPM 10000TL-HU Hybrid inverter so far which might be compatible. It is very difficult getting the right information. There must be many available but so far it is proving difficult. Then there is the actual compliance part, given that this is a self install. I suspect I'm going to have to pay for a witnessing at some point. Sometimes I wonder whether it would be better to go the ATS route and not have a grid connection at all and manage my electrical demands myself. I have often thought that since the electrical installation is yet to be designed I might be better off having a small on grid circuit and a off grid/ on grid system with a changeover.

Not so with these really. I have checked. They are quite tolerant of voltage swings. But I am certainly thinking about retro fitting boring old nasty mains. Has this thread drifted somewhat?

Yes. It's actually an amalgamation of several projects I have done over the years. And the dimmer switches work well. The only bit I haven't done before is this many RS485 nodes over this distance. But it is well with RS485 spec and RS485 is decades old and very robust so I'm not that worried about it. Suits me. My life is so much simpler now and I am getting too old for that nonsense. If I live long enough to be too old to go sailing I'll get me a couple of Whippets.

Yes.It is too many, but I can use as many as I want. Here in my stepfather's kitchen, when we are sat at the table we really only need the lights over the table on full, but we have to have all three switches on and the whole kitchen lit up due to how the 3 circuits are configured. And similar in the sitting room where I watch TV. I have to have most of the down lighters on when if fact I don't want the ones at the TV end of the room on for movie night. Or perhaps I do if it is parlour games night. (What if I want to woo a beautiful lady and the lights over the sofa are too bright?). You are right, I have been over thinking it but once the wiring is in and the ceiling up usually it can't be changed, no matter how the Feng Shui of the room transpires. For me it is about having the choice, perhaps due to my theater lighting background. I will find out if it is pointless!

I think one of the things is that I have become slightly obsessed about efficiency. It might be a bit ideological but to me it doesn't make sense to have a DC current being produced by the solar, converting it into AC via an inverter, with the losses that introduces, in order to pump it round a lighting circuit only to have it converted back into DC to power LEDs. I know that is rather pedantic and I know the LEDs have a current converter inside. And it is true that since much of the rest of the house requires 240v ac why get so uppity about it but it does bug me. When I had the consumer unit replaced in my old house a few years ago the electrician couldn't sign it off because the lighting wiring had no earth in it. So I suggested fitting a cheap 12v transformer and switching over to low voltage LEDs. It was what I was used to on my boat and meant I could get an electrical certificate. And I found it was so easy and worked well enough that I decided it was the way to go for lighting now. I wish I had gone for 24 volt at the time but I had already purchased all the LEDs so I stayed with 12v. But I take your point @G and J that future occupants might have a hard time dealing with it so I am certainly going to document it all as best I can. But my aim is that it won't need apps of any fancy panels or screens. Just knobs you turn and the lights get brighter or dimmer (properly, perceptively linear and no flickering, I hate the flickering). But beyond that there is more sophistication to the lighting system "under the hood". For me it was easy and really cheap to design a system where each LED has its own channel. And, going back to the OP and the original question, I think 24v can be a good idea but the Loxone route looks very pricey. My LED downlighters are less than £8.00 per unit including the ceiling fitting. And the control side for 80+ channels will probably be around £300-£500. The cabling will definitely be significantly more but all in all, much less than an off the shelf system. We'll see, I might fall flat on my face!

My setup is nothing at the moment as my house is being built. But I have a plan! I don't know how much detail to go into before it gets boring for you all. I have 85 8w MR16 bulbs coming on a slow boat from China at the moment from Benory lighting. They are about £4.50 per bulb and I have a mix of 4000 and 3000 colour temperatures. I have been looking over the last two years for low voltage LEDs that actually dim well at high PWM frequencies and these ones are specifically designed for it. They dim very well down to very (very) low levels at 3Khz PWM frequency and are very stable with no flicker or buzz. I have also purchased 24 x RGBW (4 channel) LED amplifiers from Alibaba at about £3.50 each. I have used these before and they seem very good and reliable, especially given how cheap they are. But then they are just mosfets in a box I guess. So I will have 96 channels available to me in my house. Each room will have between 8 and 16 channels so every single LED will be on its own channel. I have designed a control system that sits behind a standard dual gang pattress which will look like a conventional 3 gang dimmer wall switch. But inside is a micro controller (RP2040) hooked up to an RS485 network. The micro controller is responsible for generating the PWM signals and responding to the dimmer knobs and communicating with the house computer. I have the ability to run slave controls on the other side of the room , plus infrared (and my phone / laptop if I really want to). The idea is for it to be invisibly sophisticated so the light switches look and behave like normal dimmers switches but each individual LED in each room can be assigned to any knob on the room dimmer switch at any relative level (with a gamma curve). And I will be able to change the dimmer knob assignments on a whim or a schedule. (I might want different pre-sets and levels for different occasions. Who knows, maybe I'll set it up once and that will be it). I have also included temperature and door sensors. My plan is to have a 24v dc "backbone" on each floor. I have yet to do the voltage drop calculations but it might be some fairly chunky DC cable (6mm? 4mm?) that then branches off, via a busbar to each room. The LEDS will have a common positive and then each negative will be taken back to the RGBW amplifiers on .5mm cable (8w at 24v is only about .33 amps so .5mm should be plenty) I will put up to 4 RGBW amplifiers (up to 16 channels) behind some sort of elegant service hatch in the service void in the wall in each room. As for the power supply. I will probably start with a 500w 24v unit running off a 13amp plug as eventually I will have a 24v LiFePo4 battery tapped off my solar array. 80 x 8w MR16 bulbs is 640w, and that is with every single LED on at once so I don't think I need a massive supply. It works out at about 12 amps per floor, worst case. Over a 15 metre run that requires quite beefy cable if I want to obey the 3% voltage drop rule, but I will do some more calculations and start chunky and reduce it as I go further from the power supply. I think I will run 2.5mm for the common positive and then the negatives will be .5mm. I have yet to have a conversation with the electrician as he/she/they don't know what I am planning. I might run singles in a ring for the positive, I will have to see what regs apply. I have yet to set this all up so it will be interesting to see if it is a success but compared to Loxone kit I think it is likely about a 50th of the cost and will work the way I want it to with my own firmware that I can customize to my own diabolical ends. Feel free to ask more questions, or tell me I'm mad. I don't care. It's my house and no-one can tell me what to do! (I don't have a wife).

I am doing exactly this. My whole lighting circuit is going to be 24v DC and I have found some MR16 8w 24v lamps that work extremely well with PWM dimming, even at 4Khz. So I am going for a really cheap option of RGBW LED amplifiers (less than £4.00 for 4 channels), the MR16 bulbs work out at about £4.80 per bulb and will fit any MR16 fitting. I have also ordered some ES 24v bulbs to fit normal lighting fixtures. I hate mains dimming LEDs, they buzz and flicker at the cheap end of the market. I will probably try and run the whole lighting system from a 24v LiFePo4 battery eventually.

That is a handy tip indeed!

I guess that is part of this question. There are some many inverters on the market and G100 certification doesn't seem to be top of the spec list when searching. I suppose I am looking for recommendations, with the proviso that I would like to choose my own batteries, probably in the nominal 48v voltage range given that I am looking at the Fogstar range. With 24 solar panels I suppose that is 3 strings of 8 or two strings of 12. I'm completely open to suggestions. My searches so far have left me a bit bewildered by choice with no experience of any make other than Victron kit at the 12v end of the market.

I don't think 3.6kw is enough so right now I believe G98 isn't going to work for me. I only have electric, for heating, hot water, MVHR and cooking so I will go over 3.6kw at the drop of a hat. I had thought of two inverters, the Victrons can run in parallel as far as I have seen. So I think it is either a G100 compliant inverter or an external G100 device, if anybody here has experience of these. I really don't want to be tied down to propriety batteries either. I have thought about having one inverter non grid tied for running specific items such as immersion or heat pump, perhaps with a changeover option. It is very frustrating as the farm paid 12k for an upgrade to the infrastructure a few years go and they seem to have been very short sighted and installed the minimum.