MPP LV6548 for my off-grid shed

[mjgillen]

Hello all,

I've been researching a small DIY off-grid setup for my shed to power a small portable 1250w air conditioner this summer. My anticipated setup would be an AIO Inverter, a DIY 48v bank of batteries, and 2400w (6x400w) of panels on the roof. From what I've read, it seems like the MPP LV6548 is a very good AIO choice for reliability, functions/features, and price. However, it looks like these "original 250v" models are no longer in production and have been replaced by 390v and now a 500v models which may or may not be as reliable. So I am looking for advice on whether to buy an MPP LV6548 or something else?

I'm not quite ready to install my system yet and likely won't be ready to start the project until June.

I see that Watts247 has the MPP LV6548 250v version on sale as a "Winter Special" for $900. I emailed them and they have "limited stock" so not sure how long those will last.

So... Buy now from Watts247? Wait? Will more of these 250v versions become available in June? Will the 390v/500v versions prove to be just as reliable as the 250v model?

Looking for advice from the forum.

Thanks,
Michael

 

[Texican]

I have 2 of the original 250v inverters. 2 years now, never an issue
keep in mind if you ever want to go to a 240v system you will need 2 of these inverters and a second might not be avbl at that time.
with the 6 panels you have with a VOC near 50v you will need to wire as 3s2p to not exceed the 250v limit
they are good inverters, just have some limits

 

[dab61]

I have 2 of the original 250v inverters. 2 years now, never an issue
keep in mind if you ever want to go to a 240v system you will need 2 of these inverters and a second might not be avbl at that time.
with the 6 panels you have with a VOC near 50v you will need to wire as 3s2p to not exceed the 250v limit
they are good inverters, just have some limits

can you help me understand how you got the calculation of VOC near 50V? Since his array is 2400W and the unit is rated at 4000W for each of the 2 PV inputs isn't that enough margin? Newbie question...

 

[mjgillen]

can you help me understand how you got the calculation of VOC near 50V? Since his array is 2400W and the unit is rated at 4000W for each of the 2 PV inputs isn't that enough margin? Newbie question...

VOC is a characteristic of the panel such as 400w. Many 400w panels have VOC in the 40-45v range. And you want to leave some margin so you don’t fry your expensive Inverter. Thus 3 panels in series (3S) is ~150v. Make two of these and connect them in parallel (2P) for the same 150v, double the watts.

I’m a noobie too so I hope I got all that correct.

 

[mjgillen]

I ordered the MPP LV6548 250v version from Watts247. Gonna read the manual again and start collecting the other stuff I need (besides a battery and solar panels). Should be fun!