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I'm installing a 1.5 kw solar panel set and would like to share its output with two separate lithium systems - 12 volts and 48 volts. My question is can two Victron controllers be placed in the same panels output. I prefer not to switch the panels output from one bank to the other.
Many Thanks
You want to connect the two MPPTs together to the same PV array?
That will not work because both MPPTs try to find and work at the MPP. But the MPP always changes if one of the MPPT starting to pull energy from the array.
You have to install a switch, split the array or you connect the array only to the 48V system and use a DCDC converter to push energy into the 12V system.
Thanks for the reply - if the MPP changes is it not within the capability for each controller to adjust it status for the new incoming voltage be it higher or lower or different amperage's. Is this any different than when the panels drive into and back out of a shaded area and the output varies? A DC to DD converter won't work because it can not taylor the charge on the lithium and will cause a hard shutdown.
Regretfully a switch is not an option since both packs need to be charged when ever there is solar.
Thanks
Your quesion seen to be not very clear, you can not mix 12V with 48V.
Hello and thanks for the reply - Sorry however the question is clear!
I have a 1.5 KW solar panel set and I need to take the output to two controllers - a 12 volt controller for the 12 volt lithium batteries f and a 48 volt controller which I have (1550/45 TR) for the 48 volt lithium batteries. There is no connection between the batteries. The panels output is just that output it does not see battery voltage.
Therefore the question is why can't I install two controllers (not linked) to the output and let them do their own thing?
Many Thanks
M Lange
Thanks for the reply - if the MPP changes is it not within the capability for each controller to adjust it status for the new incoming voltage be it higher or lower or different amperage's. Is this any different than when the panels drive into and back out of a shaded area and the output varies? A DC to DD converter won't work because it can not taylor the charge on the lithium and will cause a hard shutdown.
Regretfully a switch is not an option since both packs need to be charged when ever there is solar.
Thanks
MPPT will not work properly sharing input as Matthais said. They need to synchronize their tracking and this is not built in.
So you're left with the options already stated, split the panels or use DC:DC chargers.
As people have advised you cant connect two MPPTs to a solar array. However rather than two MPPTs why not one 48v and then a DC/DC converter between the 48v bank and 12v bank
2 MPPT on one solar string is like two steering wheels in a car, it is not possible.
Many thanks for all the replies however there seems to be quite a bit of expert knowledge and advise that it won't work, yet no one has tried it, so would you not agree that it's "here-say" at this point!
Regardless, of what's inline of the solar panels output, it only seems logical that each controller would look at the input "available" and adjust accordingly using tracking or not, isn't that the what controllers do. If a controller was in line and another controller is added to the output and begins to draw from the panels output, the 2nd controller would adjust to work with what voltage and amperage there was remaining, it's certainly not going to shut down.
There is only one set of cables going to the roof with no options to run another so two systems is not in the picture.
A 2 way switch won't work because the owner would have to baby-sit the two systems.
The recommendation of using a DC to DC converter won't work. I have one and they are either on or off and have no lithium protocol for charging.
Best Regards - Mike
Think of it this way. Each MPPT is selfish, optimises it's input. At this point the other is being robbed/starved. Then a bit later the other optimises. This robs the first. Effectively they fight, both operate sub optimally and the panels give much less power. The optimisation process is started on a time base. Take a look at the description of a panel output and how mppt works. As soon as you go past max power point, panel output drops off a cliff. Just use one set of panels per mppt, or a DC charger as we keep saying. The orions do have a lithium profile. Or as was also said, use a suitable fixed voltage.
It is a basic electrical concept, based on physics.
You have some very smart people telling why it won't work based on the architecture and design of the MPPT.
If you don't wish to take the advice given by people capable of giving it, then don't ask for help.
Hi Mike, the Smart DC-DC do have a lithium charge profile abs can be turned off.
Regarding two chargers, I think it is more than hear say. No manufacture that I have looked at have have any detail allowing two chargers on one string of panels. From everything I have read and heard. It would be like two people shouting and unable to hear what is happening and following whoever shouts the loudest at any point in time.
