F I T, payments while being off grid

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mfred68 asked May 6, '24

F I T, payments while being off grid

I am still in the buying and planning stage to go off grid, I have 42kw of battery storage, 17kw of solar panels, (I live in very cloudy Wales) and a multiplus ii 10000/140 inverter, as well as the lynx shunt, distributer, and cerbo gx.

My current setup is a 3kw micro inverter system with a F I T which pays me around £700 a year.

The plan is to go off grid, until the battery is depleted, then set the multiplus to automatically charge from the grid ( more than likely during December)

So my question is, if the FIT system charges the batteries via the "back door" of the multiplus, as well as the other solar panels, during the summer months, I should very quickly have a full battery, at this stage, no more power would be required from the FIT array, but if I shut them down with a frequency shift, the generation meter would stop counting, meaning I'll receive less money. So I was wondering if there is a relay made to transfer all unused power from the FIT array to the grid, by disconnecting the panels to the consumer unit (which is isolated as off grid) and transfer the power to the grid line, which would also be isolated via the internal multiplus contactor.

Then set the programmable relay in the multiplus to switch the FIT panels to feed into the grid once my batteriesare full, then switch back over to battery charging once the batteries have gone down to say 80% soc.

Is such a switing system available?

Multiplus-II

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Answer 1 · 2024-05-07T08:24:06Z

matt1309 answered · May 07 at 08:24 AM

HI @mfred68

ESS is the easiest solution to achieve what you're looking for but you are technically on the grid. AC Ignore might also be another solution closer to what you describe but worth having a read on both to see which one you're looking for. ESS is easier especially if you want to schedule charging from the grid (at night which is a good way to have 60% cheaper winter bills here in the UK).

Each solution connects/disconnects the Multiplus from the grid though rather than doing what you propose and transfering the PV to the grid. (which might be DIY'able but harder to integrate as you'd have to stop counting pv in gx then as it wouldnt be connected to that system so some custom code). Whereas ESS would be designed for it.

FIT is no longer available, so i imagine editing a system to add a multiplus might void that contract. As it's very valuable now in comparison to newer export only schemes.

Assuming that isn't an issue (my guess is it will be but i'll continue anyway).
One other option could be using hot water heaters/heat pumps or other large loads that produce a useful outcome. If you're just trying to make sure the PV doesnt ramp down use dump loads that make something you will get value from. Like hot water or aircon (far less needed in wales).

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Answer 2 · 2024-05-07T08:30:25Z

Jason - UK answered · May 07 at 08:30 AM

@mfred68 I would check your T&C's of your FIT tariff. you might find you cant use the generated energy for battery storage as the FIT tariff is based on a predicted % of export. If you don't export what is expected, and they find out you have batteries, they will stop your FIT payments until you can prove you are still in compliance with the FIT T&C's.

TBH, unless you are on the highest payment tier of the FIT scheme, then you might be better off moving away from FIT and joining a energy tariff with decent export rates which give you access to cheaper off-peak rates better suited for BESS whilst still exporting on a decent tariff.

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Answer 3 · 2024-05-07T09:33:47Z

mfred68 answered · May 07 at 09:33 AM

The idea is to do all this "on the quiet" to avoid red tape and paying officials money I don't have for pushing pens, I don't want to get any outsiders involved. I do have an electrician for advice and guidance but I'm totally diying the system. (I'm not a novice, I totally rewired my house and had it signed off back in the day)

ESS could work, but it involves getting the pen pushers and red tape with all the costs, cetificates, and I wouldn't feel I was using electricity that I've generated, because I'm technically still on grid, also can't have power in the event of a power cut. As for FIT, I'm getting around 15p per kwh, so not sure if I could get more, or less if I changed it.

Ideally with 17kw of solar ide like to export if it pays 3 or 4 grand a year, but I was told I can't export more than 4kw

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Jason - UK commented · May 07 at 09:46 AM

@mfred68 I understand your want to be 'off-grid' but there is a positive to being grid connected with an ESS. You can charge your batteries during the night on off-peak energy, that way you export more during the day which is when the export rate is greater than your night time off-peak. You'll earn more that way. You can still use your ESS as a UPS in the event of a power cut, exactly what I have.

You can do the DNO application yourself and you can also commission the system yourself for signing off the DNO application. The only thing you cant get is the MCS certificate yourself but Octopus Energy dont require a MCS certificate for all installations.

I'm 17 months into not paying an energy bill because I export enough in the summer to cover my winter energy bills.

https://vrm.victronenergy.com/installation/171934/share/db6807bb

Have a look at the photos section, I have a schematic of my system in there.

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matt1309 Jason - UK commented · May 07 at 10:32 AM

I've done very similar to what Jason suggested here. Definitely check FIT T&C's first, but DNO application was far less of a nuisance than you expect. A fair few people on this forum helped provide useful materials for that. MCS on the other hand i agree tends to add £££ to any quotes you'll get and not always for increased quality.

Highly recommend the overnight power. I swapped to it last year. Much cheaper than drastically oversizing PV for winter or any generator system to help with winter short falls. I tend to only recommend full offgrid if you have hydro/wind or dont have grid at all.

I understand your sentiment though. If you try view grid as a cheap generator it tends to sit nicer. At least that's how i view/use it.

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Michelle Konzack commented · May 07 at 12:05 PM

Why not let the GTI connected to the Grid together with any 3-Phase equippement via an EnergyMeter (connected to the CerboGX) and then cut the cable to the Fusebox and put the 10kVA Inverter in between. Then connect all three phases from the original FuseBox parallel and run the House from a single phase?

Configure the Inverter/CerboGX for ESS and disable Feed-In (to prevent the Batteries are emptied)

This WHOLE thing work as an UPS, BUT, the Inverter can simply lower the voltage and feed any consumers in the house and also charge the batteries for the night.

In this case, your Inverter works like an UPS but with the EnergyMeter it can control how much Energy stay in your house.

From point view GRID, it is not even visible.

I have several customers which have done this here in Estonia and EestiEnegia/Enefit/Elektrilevi do not know anything about it because they donot go into the house itself and verify the Electric installation.

The only thing they see is, that you Feed-In lesser the day and buy lesser at night.

If you have Space, simply install an additional SmartSolar with some SolarPanels and connect it to the Battery. And if someone ask you, why your power consumption at the night is lesser, then you can simply sas, that some of your devices are now powered from the DC SolarCharger...

Nobody in Strasbourg/France, in Kehl/Germany and Lääne Virumaa/Estonia has ever gotten a complain by the Grid- or Energy-Provider.

It is a little bit piggy, but you know, the Energy Companies are always MAFIA.

Have a nice day

Michelle

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