question

It would be good to list more details.

You say six solar panels, but you need to specify what type of panel, the power rating of each panel.

I'm guessing you are thinking of having two strings of three panels, correct ?

There really is no a need to use two MPPT charge controllers, instead on just one capable of handling the complete solar panel array, which would be more efficient.

Say a SmartSolar or BlueSolar 150|70 could be what works best.

My understanding of the inverter you mention, the MultiPlus-II, is that is is a grid connectable unit, hence more electronics that you probably don't need if as you say, you will be totally off-grid. Better to use an inverter that simply converts battery DC to AC. You want to size your inverter close to your expected maximum AC loads for best efficiency. No point having a 3000VA inverter if your maximum load is only 1000VA, that is a waste. I understand you may want to use a small induction cook top during summer months.

I am wondering why for such a small system you are wanting to go to 48 Volt system, not that this is a bad choice. But is seems you might not be able to expand the solar panel due to space.

You need to think about how the system is designed, can you get with your six solar panels enough energy put back into the battery for each day during the winter months ? Okay, I am on the other side of the Earth, down under at a latitude less than where you would be, 42°South, little island called van diemans land, ja, echt ja, and I have six solar panels into a larger system, and I can tell you you are very likely to have a hard time during winter months in Nederland without having additional power input, especially when you have a run of rainy days.

In my case, I am lucky in that I have a micro-hydro power plant, which makes more than enough during the dark months. So, you do need to think very carefully to have a system that will work for you as you need and with so very little solar panels.

If your solar panels are around 400Watts each, then that is good, but if they are 200Watts each, then seeking additional advice might be good.

What type of battery, I am going to guess LiFePO4 of some sort, maybe Victron ?

45 degree angle is not high enough, when the sun reach 20-25degree max at highest point.

Like von-baron said, use smaller inverter, these ones have lower selfconsumption and even at night u shutdown to sace energy(fridge can hold temperature at night)

or two differnt ones, one 500-800 (fridge/light), another for powerfull loads. Multiplus is not needed, exept u have a gS generator for some emergency reasons

I suggest you also to use a 250V charger, where you can have usually 6 panels in series and it will deliver more power between autumn and spring

You may first want to do some simulations using the EU PVGIS tool to see what 6 solar panels can produce in Holland, and analyse your power consumption before looking at the type of inverter/charger you need ..... https://re.jrc.ec.europa.eu/pvg_tools/fr/

I have a very low power consumption and are looking to go off-grid (further south than Holland), but simulations show I would need 12-18 panels (375-400) and 15+ kWh battery storage to be on the safe side ....

I agree with the above comments.

If you can only have x6 solar panels (mine are at 55 degrease) you need them in series as Michelle says, i have and they start before the sun comes up (5 to 10 mins) and sill charging when the sun goes down. (every little bit counts right!)

One thing i have learnt is over-size as much as you can and or add a wind turbine if you can, if not you will need a small generator to take up the slack.

Dave.

Also agreeing with the above comments. I'm off-grid in London with two 415W panels (parallel though, series would start earlier but I have shading issues) and 2kWh of usable battery storage. Similar latitude and my usage is also 1kWh per day. On an average winter day I make less than a fifth of that from the solar, so I'd guess you're looking at around 3/5 with an ideal tilt.

I'd suggest a smaller inverter too to match your loads as they're most efficient close to their capacity - my 1600W is only around 75% efficient on a 70W fridge load - and make careful use of AES mode. Running the inverter in search mode saves me around 125Wh per day compared to being left on.

I would also consider alternative sources if you can - could you ground mount any panels? Add some wind (with a dump load)? Failing anything else you'd probably benefit from even a small generator.