One customer was complaining about an unstable grid, voltages fluctuating alot, and getting his electronic equipment damaged all the time. One solution is to connect the grid to an online ups, which would continuosly filter the grid, converting ac to dc, then back to ac .
However we would like to do it with Victron Energy products, as he would like to add solar, wind to the system.
Is this possible using LiFePO batteries such as Pylontech ?
I would design the system as follows :
1 multiplus II 48/5000 connected only to the grid and the batteries
1 multiplus II 48/5000 connected only to the same batteries and to the loads
2x Pylontech UF5000 batteries
1 gerbo gx
This way the multiplus which is connected to the loads only is not affected at all by the anomalies of the grid.
However the question is how do I make the two multiplus listen to pylontech with one gerbo ? Do I have to install two gerbo’s ? in this case, how do I make sure that one pylontech system gives info to two gerbos ? As it communicates over canbus , this should be possible ?
This is completely unsupported, though some have done it.
The gx can only manage one multi as well.
Multis are not a ups. They have some properties of a ups, but they do not smooth power and the failover is not as good as an actual ups.
If the gear is sensitive rather add a dedicated, ups on ac out.
We use Multiplus as UPS at a number of sites and they work fine as an inline UPS. Reaction times to grid issues are fast enough to maintain suitable power to sensitive equipment.
If you were worried about voltage spikes affecting equipment then even if you have some sort of UPS you would want to consider a surge protection device to protect it upstream.
It is possible to adjust the voltage range the Multiplus will accept or reject the grid. This could be used to make the device more or less sensitive to grid fluctuations.
As Nick says there is no way to have two Multiplus show on a single GX. You could however connect the second inverter to the DC bus via a Smart Shunt which would give you power consumption. Further care would be need to ensure the inverter shuts down on low SoC as it won’t be able to see and of the battery information from the Plyontech.
The challenge with the multi being a grid attached ups, while it is good enough for domestic purposes, some gear is more sensitive than others, and attached to a bad quality grid, you can get power dips as the output tracks the input. Voltage limits don’t seem to help much with brownouts, so if it is critical gear then either run it permanently off an islanded inverter or consider a specialist ups between the loads and inverter.
If its basic gear and you don’t care about a quick restart then the multi is fine.
I have a graveyard of UPSs here all from established brands. The build quality of them is all lower than that from any Victron device. We had an expensive online UPS flat out die on us a year ago taking everything connected to it offline and just outside it’s warranty period.
Electronic devices are typically powered via a switched mode power supply which gives them a large range of AC input voltage as they cater for various global standards. The Multi should disconnect the grid before it is out of range for the PSU.
Well, in my experience that isn’t always the case; if it can cause something as arb as a modern TV or POE switch, all with switch mode supplies, to dip then it isn’t ideal. Can’t say I have had many issues with APC/schneider gear as a core ups, though they do cost a bit.
For the most part the conditions that have caused a power dip are rare across the broad number of outages.
It is for that reason I will never attach server gear to these, but for telco/pop purpose it is adequate, few will notice the restart if it occurs and it is unlikely anything hung off these systems has a 100% uptime sla anyway.
Although are around the same price, you can use a battery charger instead of the first MP2.
But an MP2 used in charger only mode is also OK.
Although I didn’t tried, I suppose that two Cerbos can be daisy chained on the BMS-CAN with a single Pylontech and I suppose they will work, because there is no direct CAN frame from Cerbos to the Pylons, just listen to the Pylons broadcasts and a Victron presence broadcast.
I would do the following chain of equipments:
Grid
Simple charger with some minimal monitoring (Skylla TG)
Pylons
MP2 (or simple Victron Inverter, LowFreq or HighFreq)
Multiplus II 48/5000 is about half the price of a Skylla TG 48/50 in the UK currently. Plus it supports DVCC and will give you some telemetry on the state of the grid.
I will go for this solution. If successfull , I will tell in this discussion. I think that’s a good solution compared to other inline ups. Advantages are : Possibility of adding solar, wind , additional power , additional batteries.
I have tried this option in my previous installations, however the response seems not quick enough to protect the devices from the over/under-voltage situations.
It’s 10ms reaction time, inside is toroidal transformer that regulates voltage.
One thing to remember - not all of them supports two ways transformation, so need to be careful with systems that exports to grid
Works fine for 4 years, very standard equipment in Ukraine when you own private house. Popularity is not connected with war, more with a grid quality, especially during winter times.
