I want to use a Bluetti device in my motorhome and recharge it off my existing roof mounted solar. That system has an MPPT charge controller. Is it possible to do this?
Running the gas genny defeats the purpose of a power station and adding a dedicated PV panel just to recharge a power station is inefficient and redundant. Thanks.
Nunna
Hi @NunnaUrbiz
welcome to the bluetti community forum!
The Bluetti Powerstation come with a built-in MPPT. Each model have a different sized MPPT, so you need to check if you solar array is within the values of the Bluetti MPPT. Most crucial value is the Voc voltage. This shouldnt exceed the maximum input of the mppt.
greetings
Erik
In addition to what @Selfmadestrom says, on the checks to do first to ensure that your bluetti station can handle the max voltage coming from the existing mppt…
I’m trying to answer the question you may have in mind: can we put 2 mppt one behind the other (the existing mppt of your installation and the mppt on your bluetti station). I can’t guarantee that it works for all mppt combinations, I can only say that I have an external Victron smartsolar 100/20 mppt chained with the solar input of a bluetti AC200max which is also equipped with an MPPT and in my case it works well, I haven’t encountered any problems. This does not mean that it will work in your case (because you do not necessarily have a Victron MPPT and an AC200max).
Good Point @Snips1 ! Its important that the voltage dont exceed the max input of the Bluetti MPPT in the end. Have two mppts in series can work, but also can produce bad efficiency up to it doesnt really charge. Up to how the two MPPT handle with each other
“but also can produce bad efficiency up to it doesnt really charge” : Exactly; NunnaUrbiz will have to test for example that the two mppts can find
->a stable operating point (because sometimes the operating point (V / I) oscillates constantly, therefore poor efficiency)
->and that this stable operating point is the maximum power point (corresponding to the Vmp and Imp of the solar panels) because sometimes it can have a stable operating point, but which is not the maximum power point.
-Also useful when the panels are in direct sunlight, to simulate passing clouds to find out if the MPPTs can manage to recover the maximum power point!
If the 2 mppt cannot operate stably or discover the maximum power point, one solution would be to connect two Y cables between the panels and the existing mppt, to be able to connect in parallel the existing mppt and the solar input of a bluetti. (it would be necessary to disconnect the load from the existing mppt when the bluetti is recharged).
Yes, I want to know if 2 MPPT charge controllers can be connected in series. The existing controller is 10+ years old and can be replaced if the overall concept is feasible. The PV panel is an older Hitachi 36 cell, 270 watt (I think.) I’m willing to add more panels if needed but want to minimize extra effort/cost.
Long term, I want to replace the complete 12v DC system with a power station. The 6v deep cycle lead acid batteries will be replaced with a single power station. I want to minimize gas genny usage to an absolute minimum.
Thanks, I appreciate logical, rational responses, preferably based on experience. I hesitate to take much advice from forums based on “by guess & by golly.” 