Your paper is very well written, yes a good paper. Might ask you if i can put that in my book please.
You'll have to ask Studer CM. It's their intellectual property. I just happened to agree with it before I read it.
But don't forget the main Inverter H Bridge that can backfeed AC turn it to DC and charge/backfeed the batteries. Now that i am getting the hang of the back feeding regime i think i can calm down my direct DC coupled to batteries PV input to only 2.5Kw instead of the present 5Kw. This 5kW DC is on 2 very expensive MPPT controllers and i really only use these as battery charging finishers. Both have there own independent charging regimes and deal with things as required. But are not connected into the main system or themselves. Note, I much prefer the Morningstar Tristar MPPT controller over the Midnight classic 200.
I only use MS to harndle proper lead charge because no fans (although often HF singy) and specific gravity results. I buy a substantial stock of the MS MPPT orphans that turnip on ebay. This is the thing about buying robust high fidelity equipment. You can rest assured a used one is more often than not right as rain. If you buy at the right price you can sell for the same after you've had your way with it.
If we examine the graph in my previous post we see a system that is extremely well-matched input to load for that particular day at least.
I've added some data points to observe an interesting ratio.
Deploying ball-park-o-meter-scope.
Let's assume Night Load = 2.3 times the Day Load. Because the graph is pretty accommodating about lining up at ~2.3x amplitude if superimposed.
We also observe a ratio of 1:3 AC to DC coupling.
For the following reasons I expect.
AC coupling meets on-demand daytime load profile.
Battery loads are ~2.3 times greater than daytime; to provide this is a DC Coupled Array 3 X size @ 70% efficiency to use at night = 2.1x Equivalent Day Load Supply capability.
For an AC-coupled array to supply the same nighttime power it would need to be 6% larger.
One {extra solar panel / less shadow} per 20 panels.
The benefit of course of DC coupling is the redundancy whereabouts the disappearance of the installation's 230VAC voltage source does not take the battery with it.
For example when the Battery Inverter UnderVoltage Disconnect Trips the GTIs anti-island and hence reduce charge/recuperation opportunity.
What I also draw from the dataset is why are people calling batteries a greener solution for normal grid connected domestic applications? When moving from a 96% efficient system (red) with a lower setup cost and faster return of investment to a 66% efficient system with a battery to pay for too and short-changing the network 30% fossil fuel offset?
The removal of a battery from the system is the best for the network.
A Utility Battery is another matter.
As for people who want to use night rate lecky and day cycle offsetting daytime import?
If night rate = 50% day rate. Night energy = 66% efficient. Battery doubled cost of installation...
So once the GTI's input into the MIN GRID my battery use becomes minimum.
That's what doing it right looks like. I never understand why people focus more on a battery (an inefficiency bucket) than the system input.
(System input = system output) / now ....that's the proper way.
I class the OzInverter as a true 6kW output all day if the batteries could cope, however with AC Coupling, i am now back feeding and operating 12Kw of GTI's on the MINI GRID the OzInverter is managing.
My powerplant Xtender handles AC coupling fine and DC coupling fine. It's tripped it's own over-voltage threshold by latent backfeeding response in..you know those cold Autumn days when sunbeams are lensing cloud edges like an eyefulla arc weld and the array pummels the system with surges. Hitting two moving targets at instantaneous max output ain't easy. I could increase the Over-Voltage alarm trip. At the moment I've AC coupled one Xtender and DC coupled another.
The LFP is AC Coupled.
It can trip it's own over-voltage with SmartBoost hysteresis too if the threshold is too narrow.
I have yet to see if my 7kVA twinset fair any better managing a system built entirely of other manufacturers' supporting hardware inclusive of 4kW mixed couplings.
My LFP 4kVA is hibernating as of this weekend. The PowerPlant Twinset (one active, one standby) are now handling DC Coupled AC Injection. My SB1700 is on shore power only. I will link it later to backfeed through the Xtender with islanding frequency out of limit trip control for back-up usage.
There seems no point in being concerned about power injection offset & making an even distribution of oversupply between here and April and besides my solar freakin' battery heater refuses to exist on the basis of shenanigans. There will be no oversupply after the Immersion Diverter for the next 5 months.
The issue I was having is the TS Absorption + Temp compensation voltage was higher than the Inverter Over-Voltage Trip.
The Xtender can be a bit slow to react at back-feeding input surges so bigger batteries are more capable of absorbing these power pulses.
Yes it can do 50kW surges no issue, but 'Oztules' did that on some of his testing procedures, I am very chicken when it comes to that test, so i let 'Oztules' test stand on that one.
50kW..Woowee!! It'd take me a coupla minutes to find a suitable test load.
It's not a speed limit...it's a challenge.
Oh yes, the OzInverter is reasonably efficient as it uses only 35w idle power.
Yurp. My jaw did hit the floor the first time you said that.
That's quite impressive for a lump that size.
I'd say that puts you in the top 3.