Solar controller question

Using the Victron controller calculator and entering the specs of my 2 panels, it only recommends the BlueSolar 150/45.

Here are the panel specs.


I’m wondering why I couldn’t use the Victron SmartSolar 100/50?

If I wire in parallel isn’t the max voltage only the rating of the one panel voltage of 39v?

I have a 12 volt battery bank.

What’s more critical, the amp rating of the controller or the volt rating?

Voltage is the most critical rating. You can over amp a controller but if you over voltage your controller you most probably will kill it

You really need to look at all of it, but I agree that voltage is what will harm a controller. They will self-limit at their max amps, and you will just be losing available power.



The Victron 100/50 doesn't really have the current capacity for your panels. With the panels in parallel you have 600W @ 12V which is 50A. I don't recall exactly, but you are suppose to over rate by something like 15%. But again, that's most important with Voltage.


With the 150/45 that are probably configuring the panels in series. 40V (Voc) times two is 80V. For voltage I think you are suppose to overrate by 1.4, so that brings you to 112V which is too much for the 100/50, but OK for the 150/45.


I have increasingly seen people using one controller per panel, so you might want to consider that. The controller can be smaller, and with each controlling it's own panel you get the best handling of shading. But cost will be a bit more, especially by the time you are done with fuses, breakers, etc.

Don't wire two panels in series as it will result in as much as 80 V which is beyond safe DC wiring specs.


The new Victron MPPT controllers are a good deal so I would consider using two 30A controllers, one for each panel. That shouldn't require that much more expense to wire two panels/controllers in parallel. You can use one fuse/breaker at the battery bank for both as long as the wire from each controller to the battery has sufficient ampacity for the fuse/breaker rating.


David

Dc wiring specs?

The thing that strikes me about that is the maximum (zero current) open circuit voltage of 80V on the panels going tob a controller with a maximum rating of 100V. That just seems too close for continuous use. I'd want ~50% headroom .

Could you use it? Probably. Is it prudent to move up to the model with the higher rating? Probably.

Remember, their calculator isnt giving minimum spec, itbis giving their "recommendation". Mine would be the same.

Keep in mind that the amp rating is the output, not the input. Also, a solar panel will be frequently operating near the top of its voltage rating but only rarely near the top of its current rating.

I like the idea of two smaller controllers if the wiring doesn’t cause me too much trouble.

I really wanted to get a Bluetooth compatible controller because I was not interested in mounting a separate display panel, so that’s why I was looking at the SmartSolar from Victron. So I could use two of these?



Wonder how the smartphone app would handle two of these controllers in the same location?

Yes, the 100/30 model was the one I was thinking of if using two parallel controllers.


David

I was hoping I could mount these controllers down below near the battery box, so I would not have very easy access to them. That was the reason for wanting something that would connect to a smart phone app.

Isn’t it preferable to mount a controller close to the batteries?

For these panels is number 10 wire OK to run to the controller? What size wire do you run from the controller to the batteries?

Putting the controllers as close to the batteries as possible is good. They don’t have a remote voltage sense, so the shorter the wire run, the more accurate your charging will be. Victron does have a blue tooth voltage and temp monitor, but I have read that the range is quite poor.

Yeah I was wondering about that range. I have also read similar comments. My boat is pretty small, and the batteries are basically directly under the pilot house, so standing in the pilot house they would be about 3 to 4 feet away.

cardude01 said:

I was hoping I could mount these controllers down below near the battery box, so I would not have very easy access to them. That was the reason for wanting something that would connect to a smart phone app.

Isn’t it preferable to mount a controller close to the batteries?

For these panels is number 10 wire OK to run to the controller? What size wire do you run from the controller to the batteries?

Click to expand...

If you install parallel controllers then the maximum current will be about 25A for each, so 10 gauge will be fine if the controller is within a couple of feet of the batteries, but if one single controller then at 50A you need #6 to keep the voltage drop to less than a tenth of a volt.



You will need to wire your single or dual controllers to a fuse block within 6" of the battery to meet ABYC. From the fuse block to the batteries use #6. Use a 60A fuse.


David

Thanks! Tested out my panels and got 9.3 amps at 36.3 volts, which appears to be 330 watts? Is it normal for a panel to exceed the rated 300 watts on the sticker?

I have just installed the app on my Polarus 35 and have no problems with the bluetooth on my flybridge which is about 4 meters away from the controller in the engine room near the batteries. I love it.


John

djmarchand said:

If you install parallel controllers then the maximum current will be about 25A for each, so 10 gauge will be fine if the controller is within a couple of feet of the batteries, but if one single controller then at 50A you need #6 to keep the voltage drop to less than a tenth of a volt.



You will need to wire your single or dual controllers to a fuse block within 6" of the battery to meet ABYC. From the fuse block to the batteries use #6. Use a 60A fuse.


David

Click to expand...

Got it. Thanks.

What kind of fuse block are you talking about? I’ve searched around but don’t know what I’m looking for really.

So would I run four #6 wires from both controllers to this fuse block, and then two #6 wires to the battery bank? Does it matter how I hook it up to the 4 battery house bank?

Sorry for all the stupid questions, but I’m pretty stupid when it comes to this stuff. [emoji30]

If you use this terminal mount fuse block- https://www.amazon.com/Blue-Sea-Sys...nt+fuse+block&qid=1552178454&s=gateway&sr=8-7 you mount it to your battery + terminal and then run two 10 gauge plus from each controller to the block and two 10 gauge minus to the - terminal or a nearby negative buss bar.

With a four battery house bank just hook it up to the + and - terminals unless it is series/paralleled wired GC batteries then make sure you wire it to the +/- 12V terminals.


Use this 60A fuse- https://www.amazon.com/dp/B001B04Z5Y/ref=twister_B01LBPFN0E?_encoding=UTF8&psc=1


David

Awesome. Thanks again for the help.

The panel for my Magnum Inverter charger tells me what is coming into the house bank because the solar power comes into the house system at the bus bar after the Magnum shunt. It doesn’t tell me what is coming out of the Panels, unless the instantaneous house loads are near zero.

The most stupid question is the one you should have asked but didn’t!

djmarchand said:

If you use this terminal mount fuse block- https://www.amazon.com/Blue-Sea-Sys...nt+fuse+block&qid=1552178454&s=gateway&sr=8-7 you mount it to your battery + terminal and then run two 10 gauge plus from each controller to the block and two 10 gauge minus to the - terminal or a nearby negative buss bar.

With a four battery house bank just hook it up to the + and - terminals unless it is series/paralleled wired GC batteries then make sure you wire it to the +/- 12V terminals.


Use this 60A fuse- https://www.amazon.com/dp/B001B04Z5Y/ref=twister_B01LBPFN0E?_encoding=UTF8&psc=1


David

Click to expand...

The terminal fuses are awesome and versatile. The mounts are also made in a double if you need two different fuses on the same source.

Ken

twistedtree said:

Putting the controllers as close to the batteries as possible is good. They don’t have a remote voltage sense, so the shorter the wire run, the more accurate your charging will be. Victron does have a blue tooth voltage and temp monitor, but I have read that the range is quite poor.

Click to expand...

We installed a Victron BMV-712 monitor last year. Recently our boat was in a closed building getting the caprails refinished and I was concerned about how the batteries were doing. I was able to view the status from outside the building on my phone. The range is actually pretty good.

Jeremiah

I install quite a few solar panel systems. "Usually", unless an exceptional long run (over 20 feet or so), the 10 gauge is ok to run from the panels to the controller. From the controller to fuse/breaker and on to batteries no one can give you a blanket answer for that without knowing the real round trip distance. You need to figure out where the controller will be physically located in relation to the fuse and batteries, then use a voltage drop table to determine wire size. Blue Sea Systems has a free App called "Circuit Wizard" that you can download to your phone and has a great voltage drop / wire size calculator. You do want to have Victron solar controller as close to the batteries, and in the same environment if possible for the controller to know the exact voltage and temp of the batteries as these are both internal to the controller. I like to use breakers (Blue Sea 285 series) instead of fuses on these installations so you are protected and can use it as a disconnect switch. Most manuals want a fuse or breaker between the panels and controller also. I do that as standard practice.
As far as using the app to Bluetooth to two different controllers, that works fine. When you pull up the app, it will see both controllers and ask you which one you want to look at. I'm personally not a big fan of Victron inverters (although I install quite a few of them) but I am a big fan of the Victron Smart Solar controllers.
I see you are in Victoria, Texas. Where is your boat?

Thanks for the very helpful info!

Boat is on Longboat Key Fl.

cardude01 said:

I like the idea of two smaller controllers if the wiring doesn’t cause me too much trouble.

I really wanted to get a Bluetooth compatible controller because I was not interested in mounting a separate display panel, so that’s why I was looking at the SmartSolar from Victron. So I could use two of these?

View attachment 86255

Wonder how the smartphone app would handle two of these controllers in the same location?

Click to expand...

It handles them just fine. I have three, all mounted right next to each other, and a BVM-712 there also. I also have the remote voltage and temp monitor because my batteries are in one space and my charge controllers in another. They’re about 12’ apart through the floor. I can sit in the V-berth and easily check the status of everything, even the temp sensor.

I suggest the Bluetooth temp monitor because otherwise the MPPT controllers will do their temperature compensation based on the ambient temperature of the controller, not the battery. If you’re like me and have them in two completely different environments, you’ll be shortening the battery life without it.

Also, the Victron units make their own little network, so the sensor is shared between all the devices. It’s right handy, although the MPPT controllers only display temp in SI, while the BVM is more American friendly and will do either C or F.

There are several settings changes that need to be made to make everything play nice between the solar and the battery monitor, but there are several videos and tutorials available that make it pretty straightforward.

The Victron stuff is amazing. And given the price there isn’t really any reason not to give each big panel its own controller. I’ve got two 300W panels each with their own, and a pair of 100W panels in parallel to a third. Although I’ve taken the two 100W panels off line because I really don’t need them, especially not down here.

Josh

Finally made it to the boat. Can the solar controller be hooked to this positive and negative bus bar or does it have to be hooked to the battery?

It can be connected to the bus bar as long as the bus bar, wiring, and circuit protection are rated for the current.

You want to have a circuit breaker between the controller and down stream in event of a short or other resistance-reducing failure at the controller. You also want one between the panels and the controller as a service disconnect.

gkesden said:

It can be connected to the bus bar as long as the bus bar, wiring, and circuit protection are rated for the current.

+1

You want to have a circuit breaker between the controller and down stream in event of a short or other resistance-reducing failure at the controller.
You want it near the batteries or the bus

You also want one between the panels and the controller as a service disconnect.
Nice but not essential

Click to expand...

David

I guess it is worth a few words to explain the location of the circuit protection thing further...

Placing it close to the bus or battery provides the most protection, because it protects both the wires and device. So, if a hot wire chaffes and shorts to ground along the run, you are still safe.

Placing it up by the device or panel makes it easier to shut off, turn on, check, and reset -- but protects only the device, not the wiring. And many (not all) devices have built in fuses or fusable linksbor even breakers, making an external one near them somewhat redundant.

In my own boat, I have fuses on the batteries (Blue Sea 2151) near the terminal block rated for the wiring...and the breakers at or near the panel rated for each supply or load. I like the ability to turn things off and wiring a breaker is almost as east as wiring a switch, I think.

This is super true with supplies rather than loads. These are different. If a solar charger, power charger, or inverter goes wonky, you really want to be able to turn it off, be sure it is off, and be sure it stays off, before it boils your batteries.

My boat's PO didnt have this philosophy andvhad a misconfigured solar charger -- killed a bunch of house batteries and blew up (literal explosion) at least one.

If you dont want breakers near the device, and dont want to use one for a disconnect, give yourself some other way...a switch, a disconnext plug, etc. Disconnect plugs are cheap and take no panel space. At some point you'll want a convenient way to de-energize the device, I think. I know I have.

For example, when I had to open my controller to adjust the charging voltage (so float was really float), I ended up waiting to evening so a slip of the screwdriver couldnt short 20A on the panel supply side. I took that opportunity to add panel and load side breakers as disconnects.

Disconnecting load side wires was easy. But, to disconnect the panel side wires would have been above the bimini -- or inside that same energized metal box and then sliding them out of it.

...could have done it live. Work live plenty. But, I avoid it when I can. Statistically speaking. Reducing exposure keeps me and equipment safer.

Any rate, hope this helps.

"I ended up waiting to evening so a slip of the screwdriver couldnt short 20A on the panel supply side."

If you did short the panel supply with a screw driver it wouldn't hurt a thing. The panel current is limited to Isc which the wiring is fully capable of carrying indefinitely. And it will do no harm to the panels.

David

I ended up going directly to the battery. Forgot I ordered the 60 amp fuse that mounts directly to the battery terminal and that made it easy. Thanks for that recommendation David!

I did run the negative cable to the big bus bar, but it all seems to be working.

One thing I don’t have are some disconnects for the panels. Should I put a disconnect for each positive panel wire right before the controller? Or could I just throw a towel over them and disconnect using the connectors? The less I have to cut wires the better it seems.