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Finding the right gear for my powerbasement
#1
So. My roof will fit 21 mono panels of 300W. This is 7 strings of 3 panels in serie = 145V.

Later on there will be solarpanels in the garden.

But now what other gear do i need?
-An (or 2) mppt controller(s)
-An (or 2) puresine wave inverter(s) => sometimes there will be 4500w loads for 2 or 3 hours.
-An grid tie battery charger
-An bms

What do you suggest that i need to use.

Victron has great gear. But kinda expensive?
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#2
Voc (Open clamp voltage) of 60cell 300Wp panels is higher +-40V, plus you need to take into account that at lower temperatures the voltage will go up. Take this into account or you will fry the mppt controller. You can also use a grid coupled PV inverter and grid tie battery charger. Like a SMA sunny island or victron multiplus. Lots of options...
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#3
(01-23-2019, 10:45 AM)TimBelgium Wrote: Victron has great gear. But kinda expensive?

I'd say it's rather reasonably priced for what you will get. If you think something like this can be done properly for cheap then you're wrong.
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#4
(01-23-2019, 11:59 AM)sparkgap Wrote: Voc (Open clamp voltage) of 60cell 300Wp panels is higher +-40V, plus you need to take into account that at lower temperatures the voltage will go up. Take this into account or you will fry the mppt controller. You can also use a grid coupled PV inverter and grid tie battery charger. Like a SMA sunny island or victron multiplus. Lots of options...

Grid tie is not an option. This system needs to be 100% offgrid. Otherwise i need to pay grid tie takses. Witch is around 500€ every year. And goes up if i expand the solar capacity. And in a few years there will be an intelligent electricity meter that pays a ridiculus low amount of monney for electricity put on the net. And pay the full price if you use it later.
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#5
@TimBelgium I know I also pay prosumententarief.... The system mentioned above doesn't need the main grid, you can connect it but you don't have to. The battery charger/inverter unit will create the single or 3 phase grid using power from the battery. If the grid the charger/inverter has created is stable the AC PV inverter will start (takes a minute or so). Power flows directly from the AC PV inverter to the loads, what is left is used to charge the battery. If not enough energy from the PV installation is available the inverter/charger will take power from the battery.

Also that a look at pvgis http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#SA (free !) and see how much battery you need to get through nov/dec/jan/feb the only way to go off grid (in Belgium) is:
- having lots and lots of panels and a very low power usage
- having a second source of power besides PV (so you can get through winter)
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#6
Sorry. Maybe i was not 100% good with the information. The idea is that i have an offgrid solar system. But still have the grid if the battery is flat or when the inverter goes dead. In summer i probably wont be using power from the grid. In winter i will be using power from the grid. To fill the extra need that the solar then does not provide. Right now i have almost 20kWh of tested batteries. And in a few months i probably hit 40 already.
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#7
From the moment the inverter is able to inject power into the grid, you are stuck with prosumententarif. Unless you get creative and for example separate the 2 so you just charge the battery from the grid....
Also be careful when designing your system a lot will change this year with the new meters things will probably be a lot better if you have a battery +PV and are connected to the grid. You will no longer pay the prosumenten tarif... you will only pay for feeding back into the grid . You can even setup a grid connected system with a battery that will never feed back to the grid... but when the battery is full excess PV power is lost ! 
Anyway intresting times ahead for a pv/battery freak  Big Grin
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#8
If you use a Victron Multigrid & separate MPPT chargers, the multigrid can be separate to the grid but "fall back" to power load from the grid if the batteries are flat.
There is no "grid-tie" this way, (ie you would not push power to grid) only draw from grid if needed.
The multigrid units already have a large change-over contactor inside.
Normal operation:
Solar panels > MPPT chargers > batteries > multigrid > loads
when batteries are flat:
grid > multigrid (change-over relay active) > loads
Running off solar, DIY & electronics fan :-)
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