Why do I need more than one controller?

[Jim Burrow]

A curiosity question!
Over the last 30 months that I have been in this group and watching tons of youtube videos by Will P and others, I note they are all using 2 or more inverters/converters in parallel. The question I have, if one controller can handle you house load, why would I need more controllers in parallel?
Example: My house will never use any more that 3kw at one time. So why not just use one controller good for 6kw?

 

[upnorthandpersonal]

The question I have, if one controller can handle you house load, why would I need more controllers in parallel?

You don't. You need it to a) provide more power than a single one can provide or b) you need split phase/3 phase

 

[Jim Burrow]

Ok thanks. I notice several like the Growatt come with 120/220 vac so no auto transfer required. Or get on controller with 220vac and use an autotransformer. Although they my definitions are not transferrers as they do not have a primary winding and a secondary winding. The videos I have watched like from Dave Poz (I'm sure you have seen his videos) has been using an auto transfer for over a year with no problems. Although I do understand some of the issues they could have.

Anyway, thank you for your feedback. I'm using a 2424lv right now and can't handle more that 22amp of battery discharge current with a load of 400 watts before the controller shuts off for about a minute. So someday will have to upgrade.

 

[GLC]

I have 3 different controllers on different panel locations, east, south and west. I also have 2 inverters. A 4000 watt 110 that is on all the time and then i have a 110/220 inverter just in case I lose power to run my well pump. Everything is on one large battery bank.

 

[schmism]

You don't. You need it to a) provide more power than a single one can provide or b) you need split phase/3 phase

c) the redundancy if one goes down, I still have one to provide at least 3kw of power.

 

[Rednecktek]

Ok thanks. I notice several like the Growatt come with 120/220 vac so no auto transfer required.

Units like that are really just 2 smaller units mounted together in the same box. I.E. a 6048 with 110/220v output is just 2 of the 3048's in parallel and then mounted in the same box for convenience.

The other reason to use multiple SCC's is to reuse older panels. As an example if I started my little system with 6 of the 100w panels and then moved to a dozen 250w panels, trying to make the 100's play nicely with the 250's would be a pain in the butt. I could reuse them though by throwing them on their own SCC and attaching that to the battery bank. Then the 100's and the 250's wouldn't have to be manhandled into playing nicely as the battery wouldn't care at all.