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@maruno Off grid doesn't have to be as complicated as it sounds honestly! My inverter is actually a 'bit of both' and can even return energy to the grid if needed.
The main thing you need for offgrid is for the incoming mains, and solar panels, to be diverted to the inverter, and the breaker panel that feeds the rest of the house being connected to that same inverter through a single wire that would otherwise be your mains input. It's basically just 2/3 extra (admittedly chonky) wires.
@maruno well regarding the "overloading": if you put them on less filled power groups you will not have this issue, and honestly most cabling is purposely overspecced; they want you to use 2.5mm^2 cabling for 10-16A but that can easily carry 27A, as example, and you'll find it's hard to get there.
As for solar shutting down due to grid overloading: the only real option there is off-grid unfortunately, your batteries won't cause the grid voltage to drop enough for the inverters to turn back on.
@maruno if you have a rather standard digital meter, it SHOULD in theory be possible to just get the state through the P1 port, see whenever you're starting to send power back to the grid, and put that power into the batteries instead.
The battery I linked you actually has a P1 meter dongle you can just tack on for 25€, which should work with a large share of the meters out there.
but again yea, you can do it any way you want, all I'm saying is it neither has to be expensive, nor complicated 
@maruno I mean, the companies that actively reach out to market a solution to you, are definitely the most expensive options you can get on the market x3;
If you want it cheap and easy: 3x that plug-in battery as example, one per phase, 7.5kWh total, will cost you ~3k, with zero additional costs, AND you can take it with you when you move to a new place.
But it's up to you in the end, perhaps your partner's employer can help, but the cheap options are not the obvious ones usually.
@maruno @TechConnectify It's honestly purely the electrician and convenience that really drives up the costs actually!
If you want a grid tie battery it's even easier, you can buy those plug-in ones that you can plug into any wall socket for around 1k, 2.5kwh (random example from the top of google search results: https://www.homewizard.com/nl/shop/plug-in-battery/ ) of course the more easy you make it for yourself, the more you pay 
convenience costs a lot of money, especially for these kinds things.
@maruno @TechConnectify "wait but 4k is more than 1k"
correct! but I got a good car, you can get those Leafs and similar electric cars for around 2k if you look around a little, and it already got the BMS, charger, etc etc included; you're buying a complete package that you can just start using. If you compare that to having a premade 24kwh powerwall (~2500) installed by a professional (~5k+), then it is indeed cheaper to buy a second hand electric car.
@maruno @TechConnectify To even go further in this: getting a second hand electric car as your battery is even cheaper!
I got a 2013 Nissan Leaf for about 4k half a year ago, 24kWh worth batteries included, less than 70k KM on the odometer, 120KM range.
and I've driven thousands of kilometers to work and other placed in that thing already, so calculating what I saved in gasoline, assuming 6k km, which is about 300-500L gasoline, assuming 1.80€ per liter, is 540-900€, so I'm 1/4-1/2 break even!
@maruno @TechConnectify I built my own 20kWh + 5kW off grid setup, batteries included, for about 2000 euros.
LFP cells cost about 40-100 per kWh, you just have to add a BMS, inverter and some cables.
The expensive part is people. Same goes for the panels; 5kw of panels is 500€, but getting them put on your roof and cabled and all that costs (sometimes tens of) thousands, because there aren't a lot of people who do it and they want a high profit margin.
Happy to show you how to do it though
@TechConnectify I still think it's absolutely crazy how cheap solar panels are
I got my 500w panels, new and unused, for 50-60 a piece, without buying in bulk.
That's cheaper than standard plywood. It's literally CHEAPER to build a house out of SOLAR PANELS than it is to build out of low grade PLYWOOD.
They've gone up a little bit in price since but not much, you can still get 500w panels for around 70 euros a piece, example here: https://www.solar-outlet.nl/zonnepanelen/