Oversizing Solar Controller

[JonathonM]

I am going to install solar on my MH.
I currently have 240ah of AGM battery storage. Batteries are newish and I can probably get a few more years out of them.

Phase 1 (immediate) is two 250W panels and 240ah of AGM battery storage. The Victron calculator says I need a 100/30 for 500W of solar.

Phase 2 (next winter) is four 250W panels and 400ah or 600ah of LiFePo4 battery storage. The Victron calculator says I need a 150/60 controller.

I dont want to buy a small controller and upgrade to a bigger controller later.
My questions is... can I use a 150/60 controller with only 500W of solar?

[MacDaddy1111]

Originally Posted by JonathonM

I am going to install solar on my MH.
I currently have 240ah of AGM battery storage. Batteries are newish and I can probably get a few more years out of them.

Phase 1 (immediate) is two 250W panels and 240ah of AGM battery storage. The Victron calculator says I need a 100/30 for 500W of solar.

Phase 2 (next winter) is four 250W panels and 400ah or 600ah of LiFePo4 battery storage. The Victron calculator says I need a 150/60 controller.

I dont want to buy a small controller and upgrade to a bigger controller later.
My questions is... can I use a 150/60 controller with only 500W of solar?

Sure can! I have 1400 of roof and 600 I plug in to 2 sets of controllers when needed

[SJ-Chris]

Oversizing your solar charge controller causes no issue (...just costs a little more). If you know/think you will be adding more solar later then it is 100% the right thing to do.


Good luck!
Chris

[Mark_K5LXP]

Another way to look at it - what happens when you have " four 250W panels and 400ah or 600ah of LiFePo4 battery storage", and a 150/60 controller on a cloudy day?

Mark B.
Albuquerque, NM

[JonathonM]

Originally Posted by Mark_K5LXP

Another way to look at it - what happens when you have " four 250W panels and 400ah or 600ah of LiFePo4 battery storage", and a 150/60 controller on a cloudy day?

Mark B.
Albuquerque, NM

The kids get to watch a movie.

[Mark_K5LXP]

Originally Posted by JonathonM

The kids get to watch a movie.

And, an "oversized" controller (little panel output vs controller capacity).

Mark B.
Albuquerque, NM

[Pappion]

The 1st number is the panel max voltage. Do not exceed it. You did not spec your panels.

I have Victron 100/50 for the 3 panels on the roof. 230W at 48.7V Voc each in parallel. Series of 2 would be to close to the 100v limit, especially during atmospheric lensing.

I have a 2nd Victron 100/30 for 2 panels on the ground. These small 190W panels came with the travel tailer. They have a good tilt and are helpful in the winter.

The Victrons participate in a Bluetooth network. First on awake in the morning takes the lead. Victron Shunt also contributes the battery voltage to the network.

[Bobby F]

Just sort of a side note: There is something to be said for redundancy. Two smallish controllers versus one big one might pay off some day if one dies on a trip.

[JonathonM]

Originally Posted by Bobby F

Just sort of a side note: There is something to be said for redundancy. Two smallish controllers versus one big one might pay off some day if one dies on a trip.

Good point. One 150/60 is actually more expensive than two 100/50.
If you have 4x100aH batteries, how would you connect the two controllers to four batteries? One controller to two batteries or both controllers to all batteries?

Im still beginning to understand solar, batteries and how these controllers work...

[Pappion]

Originally Posted by JonathonM

Good point. One 150/60 is actually more expensive than two 100/50.
If you have 4x100aH batteries, how would you connect the two controllers to four batteries? One controller to two batteries or both controllers to all batteries?

Im still beginning to understand solar, batteries and how these controllers work...

Both to the batteries. Victron solar networks together and acts as one foe Bulk and Float.

[SafariBen]

Originally Posted by JonathonM

Good point. One 150/60 is actually more expensive than two 100/50.
If you have 4x100aH batteries, how would you connect the two controllers to four batteries? One controller to two batteries or both controllers to all batteries?

Im still beginning to understand solar, batteries and how these controllers work...

Interesting, the 60A is marginal with 1000w of solar, if you ever got full sun in cold temps, not likely, but possible. The 150V is plenty, if you really only get 71VOC at 10C, then I think you're fine with a 100V controller (that voltage you do NOT want to exceed, the 50 or 60 amp output will just be limited, the voltage will damage the controller). 100A is obviously way more than 60A charge current.

[JonathonM]

Originally Posted by Pappion

Both to the batteries. Victron solar networks together and acts as one foe Bulk and Float.

How do they do this?
Ive read the user manual for the 100/50 but cant find an explanation for how two or more controllers network.

[Bobby F]

I have set up systems with 2 SCC's operating off of different panel arrays feeding into the same battery bank.

I have never had a problem with this arrangement, and the charging occurs as quickly as one would expect with a single double-size SCC.

The "networking" of SCC's - to, I guess, maximize output - seems to me to be an unneeded feature.

[Pappion]

Originally Posted by JonathonM

How do they do this?
Ive read the user manual for the 100/50 but cant find an explanation for how two or more controllers network.

It's a bluetooth network. SmartSolar models have bluetooth. Easy setup on my phones Victron app.