Miko

Hello. without hesitation I use the Economic Mode and it is the one that I recommend.
I can only speak from my experience and testing and tell you why I don't use general mode.
GENERAL MODE
1) WITH MAINS GRID ENERGY AVAILABLE
Situation A) When there is enough PV power:
A.1) Covers all loads (essential and non-essential), A.2) Surplus PV power is used to charge the batteries until fully charged to 100% SOC or SOC configured with PV Master, A.3 ) if there is still surplus, it is exported to the grid up to the maximum value in watts indicated elsewhere in the configuration of the PV master application (can be 0)
Situation B )  If there is no excess PV or it is at night:
The energy that is missing to cover the essential and non-essential consumptions is extracted from: 1) Batteries to the extent possible (battery discharges can be huge up to the Nominal Total of 4600 vA depending on the GRAND TOTAL (ESSENTIAL + NON-ESSENTIAL) of the loads in your home and the limit of that discharge (in amps) will be given by what the BMS reports to your inverter, while the total energy extracted from the batteries will be given by the configured DOD and only when the batteries are discharged ( DOD reached) or if the totality of the Power of the batteries supports only the essential loads and there is a requirement of the Non-Essential Loads that the batteries cannot cover:, it will use the GRID to maintain its TOTAL Loads
Here we stop to expose one of the 2 reasons why I do not use the General Mode: Although the Batteries are DISCHARGED, IT DOES NOT USE MAINS ENERGY to charge them. That is, General Mode will only charge your batteries with excess PV, it will never use GRID, you will have to wait for PV Power to be available to charge your batteries.
2) THERE IS NO GRID AVAILABLE
It works as a backup mode, the batteries supplement the energy that is missing from the photovoltaic. Only essential loads are taken into account. Due to anti-islanding protection, non-essential loads are cut off. Economic mode, in the case of GRID Cut also works exactly the same.
From the above description it is clear why the GENERAL MODE "is not cheap at all". It is true that it prioritizes your pocket from the point of view of importing energy from the GRID, but it does not take care of the most valuable part of your installation: the batteries.
Second reason I don't use general mode is that there is no current limit it draws from batteries with GRID available. It is "on demand" and the more violently the battery discharges, the shorter its life cycle.
Correctly configured with Economic Mode you will not have these problems and you will be able to make the most of your photovoltaic surplus.
 

Just my 2c.
With 5 x 3.5kWh Pylontechs, would one then be looking at 17.5kWh of storage, with a combined charging capacity of (37A x 5 = ) 185A ? I don't understand the logic of limiting the charging current from grid with a battery bank of this size.
Would have made sense (if one could mimic the controlling of the Sunsynk/Deye) to discharge to around 40-50% capacity, switch to grid, keep a reserve on standby for loadshedding, and then just charge and run from solar the next day with the 6kW of panels. And then for cloudy days do a top-up grid charge at full power from 3-6pm or so.

There are by now a number of different versions of this inverter, but most of them will be 4600VA, and the eco % is a % of that. Either way, it should be easy to test, set ECO charge to 10% and note the value (assuming the batteries are not near full).
That is the upper limit on the charge rate - it may be further limited by your battery SoC or voltage as well as the BMS.
The "about 73A" part will depend on your battery voltage - since power is fixed by the setting, and the battery voltage determined by it's design and SoC, the current will obviously be the only variable left to change: P=VI.
 

OK... I did check the Goodwe web site this morning, because at least one of us is clearly misinformed. They say that continuous maximum charge current is 100A. That correlates with your figure of 5kw, but it doesn't fit with what I observe (yesterday a setting of 80% of rated power resulted in 3.6kw from the grid at a time when there was no PV available.
Well, see above. One of us misunderstands the inverter's charging capability. But either way, the charge current is not going to send more than that rated current over the pair of cables that exit the inverter. So I don't think your batteries are going to get charged at 37A.

At this point, both of us should be hoping that an expert will jump into this conversation. In the meantime, and remembering that I'm not an engineer, but just an owner who does use that eco mode and has spent a while trying to make sense of it. You should probably double check anything I say.
 
This must have happened to me, but I can't think of a specific date when it did. If I could, I'd go check on SEMS and see what happened. I would expect that in the absence of grid what happens very much depends on the ratio of available PV to load, and on SOC.

If PV > Load then I'd expect that it services the load and the balance is for charging the battery. But you can't use what isn't there, so if the PV after servicing the load is less than the charge current you specified, then that's what you'll get.

If PV < load then it has no choice but to use the battery to service the load.

Both are effectively the same as general mode with the grid is down - service the load, then charge the battery if it needs it and if you can. But please double check.

This, BTW, is where installers add value. We can expect them to be familiar with the equipment they sell, and thus to be able to answer this sort of question. If you can't get any information from any other source, try Goodwe support. There is a wide range of opinions about this channel, but in my experience they have been helpful.
 

I know a bit about charging in eco mode. 
You'll be asked to specify a % of rated power. The rated power in your case is 4600w. So if you set it to charge at 80%, it will charge at 0.8x4.6kw - about 73A. It will use a combination of grid and available PV.
You need to understand how much current your batteries can receive, and certainly don't exceed that. If you bought this system through an installing company, ask them for a reccomendation. 
Ok... I have 10kwh of battery. This battery can take 125A. This morning, with a forecast for bad weather and early morning load shedding, I used eco mode to charge at 80% from 4:30 to 5:30. This increased SOC by 30% over that one hour. It seems to have drawn a steady 3.6 +kw from the grid, serviced a load of about 600w, and sent 3kw to the batteries. 
I would think that on sunny days, general mode will still be your best bet. When weather isn't great, then you can probably charge faster in eco mode than backup mode, so you can use eco mode preemptively for an hour or two (I incline to two one hour slots a day, but that's just me). 
It seems to me that if you just set a charge rule or rules, outside of the specified times, the inverter behaves as if it is in general mode. 
I like to have a full battery going into the evening, so my default strategy is to charge at 80% from 15:00 to 16:00. Outside of those hours the system behaves as usual. If the battery is charged by 15:00 (usually it is on a sunny day) then nothing happens. But if SOC is low and if there is grid, the battery gets a charge. 
I don't know what the discharge setting does. I don't really need to. I just use the charge settings to charge preemptively, as described. 
Forced charging at high current might not be optimal for the batteries. Same goes for holding them fully charged. Again, get a reccomendation or seek the information.