Solar: It’s been a couple years. Got rusty.

[Chotu]

I have the Outback FlexMax 80 charge controller and a pair of 350 watt panels.

I’m looking to add another pair of 350 watt panels.

I’m not understanding the exact meaning of the following. Can it support 1400 watts of solar?


NEC Recommended Solar Maximum Array STC Nameplate
12VDC systems: 1000W / 24VDC systems: 2000W
48VDC systems: 4000W / 60VDC systems: 5000W

Is this the solar panel system voltage? Not my battery system voltage?

https://www.outbackpower.com/downloa.../specsheet.pdf

[dksail]

STC means Standard Test Conditions which in your case is most likely 350W/Panel. They recommend that if you have a 12V battery system, the max panel wattage should be 1000 W. It would support 2000W if you have a 24V battery system.

[Chotu]

Think I answered my own question.

80 amp controller. 12 volt output. 960 watts throughput.

BUT, panels are always less than ideal so maybe I can do 1400 watts given real power will never reach that?

Still confused

[noelex 77]

It is the recommended maximum solar array size. The charge controller is limited by a maximum current of 80A for both input and output. So a larger solar array size is possible if you have a higher battery bank voltage.

1400w of solar is only recommended if you have a 24v (or higher) house bank.

[Chotu]

Originally Posted by dksail

STC means Standard Test Conditions which in your case is most likely 350W/Panel. They recommend that if you have a 12V battery system, the max panel wattage should be 1000 W. It would support 2000W if you have a 24V battery system.

Thank you!

So I need another controller for sure.

Is it ok to just put the two controllers in parallel on the battery charging side or will they interfere with each other?

[dksail]

Going much beyond 1000 Watts would most likely be problematic. There could be a cool day at noon with a bright sky and cloud effects that could push your panels near or past the 350W each, for a short period, even if they are somewhat old. It sounds like the controller would have issues with that.

[sy_gilana]

dksail has it right.

Interestingly, I have just installed 2x330 watt panels. So the max I should see is 660w in an ideal world.


BUT


on my new Victron Smart 100/50, the history shows that I got 718 watts out of the system. I have never seen advertised values exceeded, until now.

[Chotu]

Ok.

Guess I need another controller to complete my system.

Can you wire both controllers in parallel on the battery charging side or will they interfere with each other ruining the smart charging features?

[rslifkin]

2 controllers in parallel should be just fine. It's ideal if the controllers can talk (like the Victron stuff and probably some others) to coordinate dropping to float, etc. But even without that, it'll work.

[Bycrick]

You can connect multiple Outback chargers in parallel. They’ll network just fine, but you’ll probably need to add their network hub to have enough ports.

[Chotu]

Originally Posted by Bycrick

You can connect multiple Outback chargers in parallel. They’ll network just fine, but you’ll probably need to add their network hub to have enough ports.

So you have to network them? I only have 2. Or will have 2.

[Bycrick]

Ah, the devil is in the details. I started out with the inverter/charger. It had no display and no controls. So I also needed the Mate remote panel. When I got the Fkexmax, I wanted to add it to the two existing devices. That meant adding the hub.

But the Flexmax has a control panel for programming. You could certainly just install them in parallel, but then you’d have to program each of them separately, and each would work independently. You’d have to ask Outback if they’ll work together without the remote panel and hub.

[noelex 77]

You do not have to network the controllers.

Two controllers in parallel works fine. If you network the controllers the output will be slightly better in some circumstances, and the batteries will be charged a little more accurately, but the difference is small.

I had an Outback controller on my last boat, but it was a single controller only so I do not know what is involved to set up the network. It will probably require some additional equipment and if so the Outback accessories can be expensive. If you decide to do this enquire about the extra cost involved in achieving battery return amp termination. We did have this on the last boat and does also slightly improve the charging accuracy. I suspect some of the required equipment will be the same as needed for achieving networking so the extra cost of this feature may not be significant.

The other trap is that sometimes equipment like this needs the same software version to network successfully. I do not know if this applies to Outback, but it would be better to find out before you commit. The Outback software cannot be upgraded by the user so you may need to send the old controller back to accomplish this.

[sailingchiro]

Another controller would be great. You could also split the panels between starbaord and port panels just in case one side is shaded. Controllers are not that expensive. Spend your money on storage capacity.

[Chotu]

Originally Posted by sailingchiro

Another controller would be great. You could also split the panels between starbaord and port panels just in case one side is shaded. Controllers are not that expensive. Spend your money on storage capacity.

Ok. This is the plan. I’ll get the other controller, program the same and see how it goes.

I do have the panels split port and starboard in my design (starboard already installed).

However, I have a unique approach to power. I have a unique approach to everything. Ha ha.

I have 1400 watts solar and 440 AH of lead acid batteries. I’m trying to avoid moving to 660AH.

I’m keeping the lead mine off my boat and instead of storage, have excess lightweight solar.

I’m focused on power generation, rather than storage, which is lighter.

All day long I have excess power. Oodles of it. I’m awake during the day, so watermaker runs, dishes get washed. Laundry if needed. Autopilot if needed.

Then at night, I’m asleep. So only the refrigerator and freezer are running. These take about 100AH overnight.

Next morning I’m charging at max acceptance and full by lunch or so, free to do all the chores and stuff again.

And no heavy battery bank.

If I run low due to prolonged overcast days for some reason, I have generators and a 70amp PWM battery charger.