Hi.
I want to build an energy storage system to do pure peak shaving in my home.
So basically I want to couple an inverter/charger with lithium batteries charging
the batteries from the grid during off-peak hours and then powering the whole house by using the batteries during peak hours. Let's assume that this "plan" makes financial sense from the point of view of the energy rates during off-peak/peak hours.
To implement this I'm inclined to choose a Multiplus II (230v AC/48v DC) plus some pylontech batteries (they are rack-style batteries with bms and CAN and they are, I think, compatible with any GX device). However I have two "lines of doubts":
The first line of doubts is about the efficiency of the Multiplus II.
Looking at my consumption patterns I'm not sure if the 48/5000/70-50 model would be enough or if I should go with the 48/8000/110-100. If the actual power available with the 48/5000/70-50 was close to the 4000W at 25C I think I could get away with the smaller unit without having to change consumption patterns too much. And obviously the 6400W at 25C of the 48/8000/110-100 would be enough.
Come to think of it I'm not even sure if the 4000W and 6400W figures are the power available on the AC out or the power extracted from the batteries.
Anyways, it's all about efficiency. I see a maximum efficiency figure of 96% for the 48/5000/70-50 but I'm not sure what that means. The ideal would be an efficiency curve with the load on the X axis and the efficiency percentage on the Y exis. Kinda like what's provided with good quality PSU for PC's.
Is Victron providing such information anywhere? It's not in the brochure but maybe it could be found in some more technical document.
The second line of doubts is about the maximum noise of those two units (which obviously is also connected with the efficiency question).
Obviously there is at least one fan in there. And from the
videos I've seen online it seems to ramp up and down with the load. However I don't see anywhere in the brochure any mention about noise. Not even the maximum db at one meter distance which I've seen with units of other brands.
Is this information available anywhere?
Absent that, is anyone with one of those units able to share their experiences regarding noise at various load levels.
If I'm not mistaken, Victron is really big in the van/boat world. So, because of the inherently small spaces involved in those kinds of applications, I would immagine that
they would be making pretty efficient (and hence less noisy) inverter/charger units.
Thanks for any suggestion/insight/etc.
John
