Yes yes, this is what I meant.
Thank you, this makes sense to me indeed. Then I am quite content with my results thus far.
Lets say I add another MPPT with another 2,4Kw of panels. So assuming 80% efficiency again, the paralleled MPPTS should then be able to deliver 70amps? And if memory serves, up to 4000W on an 48V system?
Looking at the picture, the derating recently discussed is not happening. There is slightly over 2400W of loads, and the inverter carrying around 2400W of it (which is its maximum grid-tied capacity).
The MPPT is maxed out as Louis said. That is what is happening. If you add more panels, you’ll need a second MPPT, or a larger one. The least expensive option would probably be another 150/35.
Efficiency-wise, the Multi is usually somewhere between 85% and 92% efficient, depending on how hot it is running. On average I find that it is around 88% efficient, so you should expect around 12% of the energy to get lost (between the DC and AC side). So while it is making 2400W on the AC side, it will draw just over 2.7kW from the batteries/MPPTs.
Ah! This also probably explains why I see a “peak” of around 4700W from my two 150/45s? Say my US3000s are sitting at 52.4V, then the MPPTs can only generate 52.4*90 = 4,700? Would the MPPTs not run at a slightly higher voltage than the batteries, to not cause the batteries and MPPTs to want to equally contribute to the loads (I don’t know anything about electricity and as such my intuition can be completely off here)?
Correct
No not quite. They will want to equalize the voltage.
Think of it like two jojo water tanks connected together. The height of the water is your voltage.
If you add to the one tank it will flow through the connection to the other tank and the level (voltage) will be the same in both tanks.
If you add water faster (your current) it will just flow faster to the other tank until your connection pipe cannot handle the water flow. By that time your electric cable (the pipe) will start heating up and melt, so you should have added a bigger cable/pipe.
Ah okay, so will the batteries then not also get used all the time (a little bit)?
They should not no. It is easier to get power from the thing pulling up than from the one pulling down. So least resistance will be used first (the power from the charger).
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Thanks for all the responses guys. You have also basically touched on something that I have experienced firsthand today (quite alarmingly so) and I need to find a way to resolve this.
It was fairly overcast today…
So I have programmed my geyser timer amongst other times, to come on from 15h00 to 16h00 to give it that boost for the night use. Of course you all see where I’m going with this, probably having had to deal with it eons ago.
So when the sun is not absolutely moering my PV’s, the battery steps up to the plate and supply up to 51amps at a time continuously. I know enough about batteries to know that this will toast lead acids in less than 6 months if this goes on.
So my ideas are as follows:
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Start by replacing the geyser element with a 2Kw unit.
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Add a further 6 panels. I already have another 150 | 35 MPPT so it would be only the panels expense.
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Make use of the sched charging trick to keep the system from using the batteries at night (geyser’s other times to work is 21h00 - 20h00 and 05h00 - 06h30)
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The oven which wifey so loves to use, would have to only be used in this sched charging time.
Are there any other things to do on the inverter’s side? For example, I know one can program the max output on it, but can it be done for only a certain time of day maybe?
What do you guys do? Looking for ideas please.
With regards to the geyser that is set to turn on from 15h00 - 16h00 ( maybe I should also make this a little earlier in the day), would it work if I add another scheduled charging during that same time? Would the batteries be left alone then but the panels will still supply what it can? Or does it not work like that?
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You have not done that yet … sacrilege! 
Jip, I do that.
Yes, the people here told me, AND helped me, with Home Assistant, and one can do a shiite load of stuff with it, far beyond Victron.
But still, the core functioning of my system, I left that on the Venus, using a Cronjob, like I schedule the inverter output power by times of the day etc.
See here: Victron Cronjobs
Interesting that you have to heat at 16:00 to get to the night.
I heat my 200l geyser to 55 degrees (3kW element) from 12-13 and it is fine until the next morning for dishes (geyser for kitchen and family bathroom, only bathe our baby there).
Heat main bedroom’s 100l geyser to 60 degrees (2kW element) between 13:15 and 14:30, which is perfect for nighttime shower. I believe it might still be fine in the morning, but I don’t take that chance. Have my inverter on scheduled charging between 5am and 6am with the geyser then coming on for an hour.
Technically the timers on the geysers are allowed to turn then on until 16:00, but they always just need to run for the times above, unless there’s a lot of afternoon dishes, then the 3kW element might need another 30mins or so to be back at 55 degrees.
Strictly speaking it probably shouldn’t be necessary, I’m still experimenting. We have one geyser and we are three in the household with basically the same bathroom schedule. Think its a 150L
And the geyser is enclosed in its own box on the roof outside so I believe it is ok-ish insulated. Thinking of also wrapping it in a geyser blanket to improve heat retainment even more.
So this cronjob stuff, haven’t looked at it yet, but can this make the inverter to leave the batteries alone and only use what the panels can supply during the day?
My gut feeling tells me this might be tricky seeing as the batteries and PV’s are basically integrated on the DC side. Still, this should be possible by playing with SOC and voltage settings?
Or is the best we can do to limit inverter power during certain times of the day? I will suffer a small coronary arrest if I see 50+ amps being pulled from my lead acids again hahahaha.
As far as Home Assistant goes, this might be a very distant future project, not even sure exactly what it is, sound like an Alexa type setup lol.
You can “toor” with Cronjobs.
Like:
# 9am - Set Inverter to 4kw at 9am - after kitchen usage has been reduced.
00 07 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/MaxDischargePower SetValue 4000
# 10am - Push SOC up a wee bit, gearing up for evening use, less use of batteries to heat geyers.
00 08 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/MinimumSocLimit SetValue 70
# 13h30 - Push SOC up some more
30 11 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/MinimumSocLimit SetValue 75
# 16h30 - Push SOC up some more
30 14 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/MinimumSocLimit SetValue 90
# 5pm - Limit inverter power to 100w during cooking times
00 15 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/MaxDischargePower SetValue 100
# 10pm - Drop SOC for evening use and increase inverter power for average evening loads
00 20 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/MinimumSocLimit SetValue 50
# 10pm - Up inverter power from 100w to 500w
00 20 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/MaxDischargePower SetValue 500
Or use:
# 5pm set system to Keep Batteries charged
00 15 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/State SetValue 9
# 10pm set batteries to Optimized BatteryLife to allow discharging again
00 20 * * * root /usr/bin/dbus -y com.victronenergy.settings /Settings/CGwacs/BatteryLife/State SetValue 1
Or use Scheduled Charging.
With all the above on the Venus, you are as close to the source as you can be, no RPi to go honkey, no Pc someone switched off … as long as the Venus runs, it will work … and the Venus will always work. 
Yes I don’t require anything too fancy at this point in time.
Before I start bugging you as to how to do these cronjobbies, just two other questions that I need to clear up in my mind please.
- During daylight hours with good sun. Will the PV still be utilized with the grid when I have scheduled charging on? Or will everything then come from the grid?
If that doesn’t work, then I think the option would be to limit inverter power for times the geyser and the oven runs.
- What about the “Keep batteries Charged” option? If I use this setting only for those times the geyser and oven runs. Will PV still be utilized with the grid if this happens during daylight hours?
Guys bear in mind that my simplistic rookie goals currently only are:
- Using PV to help with geyser and oven using PV;
- Whilst simultaneously being kind to the batteries in terms of amps drawn.
Looking for simple straight forward solutions. How do I do this?
If you set schedule charging on, and don’t want to use any Eskom, set the SOC very low, like 20% of some such.
If you switch it to Keep Charged and the batts are at a lower SOC than 100%, then Eskom will be used to charge them. This setting is like HKGK, laai die batts NOU!!! … and keep them charged at all times.
If you leave the system daytime as is, it works best. No interference.
You limit the max the batts will be used, by:
- The Min SOC setting.
- The max charge amps which automatically limits the DC side max amps, in and out as well as the MPPT’s potential.
- The max watts the inverter can run at.
Cronjobs is when you want to like not use any batts for cooking supper, or use less batts or when you want to power the house from batts during certain times at a max wattage to not strain the batts.
The way Victron software runs is optimal already. So I would not fiddle too much during peak sun hours.
Get the 2kw element in first, that solves a lot of drama if you heat geysers peak times, using some form of timer, with the panels able to provide all the power with ease. Come winter, the rules change.
Your questions may seem easy to do, not complicated, and they are easy and not complicated … but as you delve deeper into it all, the complications come out of the woodwork. 
Cronjobs are easy … once the penny drops.
If I, a Linux non-supported, can do them from a Windows PC on my Venus … then it has to be easy.
So, I am trying to do the same. Quite manually at the moment, but basically using scheduled charging.
I have noticed that sometimes on scheduled charging, my MPPTs don’t ramp up once the batteries are at 100% (but when I switch off scheduled charging and on “Keep Batteries Charged” it does ramp up). Not sure if it is just a bug on my side, but I’m going to upload some new config file to my inverter soon (hopefully this weekend I’ll get time to play) which would not allow Eskom to charge my batteries. Then I would be able to put it on “Keep Batteries Charged” on cloudy days.
My aim to is get it automated in Home Assistant - Effectively when the batteries are being drawn upon too much (say > 10A) during daylight hours, switch on “Keep Batteries Charged”. I’ll definitely have to fine tune the rules over time, because typically “simple” solutions like what I am proposing would not be optimal.
Yes, I have seen this during the night time when I use this. So during the day also, Eskom will not be used. But PV will be utilized then? This is what I’m trying to establish.
But what will happen if the batteries are already 100% charged? Eskom I suppose will then only top them up as and when the loads drain them. And with full PV available during the day? Will no PV be used then?
With regards to item 2. When I look at DVCC section, my max charge amps was set at 30A. So why was the geyser able to pull 50+ amps from it?
This seems exactly what I would want to achieve. But yes, MPPT needs to do its thing when the batteries are full. I really hope its just a bug and that you manage to sort it out.