Newbie solar controller question

[john61ct]

No it's just the solution to the (IMO minor) annoyance you raised.

[CatNewBee]

You can connect one bt device at a time to the same tablet.

There is another issue, independent controller have independent set points for float, absorption, equalization, temp compensation etc. Especially with LFP you want an easy to monitor system without tweaking to many devices. A single controller keeps it simpler.

I guess with FLA not too much of an issue..

[Suijin]

Originally Posted by BigAl.NZ

How does the Bluetooth monitoring work with multiple controllers?

Do you need to disconnected and reconnect to each different controller to view the stats? (Because if so that would get really annoying!)

Cheers

Al

The Bluetooth app will show a list of controllers. Easy to swap between them.

Another advantage of multiple controllers is being able to see exactly what each panel is doing which is helpful when diagnosing problems.

Also makes it easy to shut down one panel and leave the other up, if necessary.

I have two controllers, one for each 270w panel. Very happy with the setup.

[gwbull]

We have 2 panels wired individually to 2 Victron smart solar controllers with a Victron bmv 712 monitor. We have networked all components and can view (and correct, change, etc) quickly and easily on our iPhone or iPad. No need to jump thru hoops. All info is at our fingertips. We like this.
Just one remaining mystery — maybe a setting error — but only one panel delivers. The other has power we can see on screen, but delivers 0. Could be a controller problem maybe. But if we can correct this failure we’ll be quite pleased with the ease of this system.

[noelex 77]

Originally Posted by gwbull

The other has power we can see on screen, but delivers 0. Could be a controller problem maybe. But if we can correct this failure we’ll be quite pleased with the ease of this system.

If you can post a screen shot showing the output, and the battery settings of defective controller the diagnosis should be straightforward.

[Uncle Bob]

Originally Posted by noelex 77

Multiple controllers (ideally one per panel) generally harvest the most power from marine solar panels. Given you already have the wiring installed I would not change this system. Multiple small controllers are usually not much more expensive than a larger single controller, but this depends on the available models and pricing, so you need to check.



The difference in the total harvested output between a solar array wired in parallel and one controller per panel is not high, but in general the one controller per panel will deliver more total output in a marine installation.

The easiest way to explain the difference is to understand that the purpose of an MPPT controller is to select the ideal voltage where the solar panel produces the most power. Thus the controller is continually adjusting its input voltage to find this ideal point where the power produced is optimal.

However, each controller can only have one input voltage. Solar panels that are in different conditions (for example if one panel is in full sun and another is partially shaded, perhaps by the mast) will have significantly different voltages where they producing the maximum power. A single controller must select a compromise voltage. One controller per panel allows each controller to have a different input voltage depending on the needs of panel it is wired too. Thus the total output is higher.

There are drawbacks. Multiple controllers have more self consumption and there can be occasional conflicts between the charge algorithms that are working independently. But in general providing you are prepared for slightly more complicated wiring, a slightly higher total cost (although this varies between a lot more expensive to actually cheaper depending on the particulars), then multiple controllers are superior.

The other advantage of multiple controllers is redundancy. MPPT controllers are not the most reliable bits of electronics, so multiple units are nice to have, especially with high voltage panels, as these cannot be directly connected to the batteries without very reduced output.

There are other options. Rather than one controller per panel, one controller for panels on the port side and one controller for panels on the starboard side (or variations on this theme) are a popular option. The aim is to group panels that are likely to be experiencing similar conditions to one controller, thereby achieving most of the voltage matching advantages of one controller per panel.

Thanks, I see that you are referring to an MPPT controller, I am still in the dark ages with 12 volt nominal panels in parallel through a PWM controller and as far as I can see it is not worth switching to an MPPT controller unless I wanted to switch to higher voltage panels.

[noelex 77]

Originally Posted by Uncle Bob

Thanks, I see that you are referring to an MPPT controller, I am still in the dark ages with 12 volt nominal panels in parallel through a PWM controller and as far as I can see it is not worth switching to an MPPT controller unless I wanted to switch to higher voltage panels.

This has been said many times on this forum so I can understand why you have come to this conclusion, but it is not accurate in my view.

12v nominal panels typically have a Vmp of around 17.5v so even allowing for some reduction in the real world that is due mainly to temperature effects (the STC under which solar cells specifications are produced specifies an unrealistically low cell temperature) and electrical losses associated with the voltage conversion, there are gains produced by using MPPT controllers instead of PWM controllers with nominal 12v panels.

MaineSail did some formal tests a few years ago. See the link below (while you are visiting his website take the time to read the other articles, they are all excellent):

https://marinehowto.com/mppt-vs-pwm-solar-controllers/

He found a 20.8% gain when using a MPPT controller compared to a PWM controller with 12v nominal panels. This was with LiFePO4 batteries. With these batteries the gain is higher and MaineSail estimated a 10-20% gain if lead acid batteries were used.

On our previous boat I switched from a PWM controller to a MPPT controller with 12v nominal panels. I estimated the gain as being around 5-10%. This estimation was without the excellent well controlled test such as the one cited above. Nevertheless, I know our solar system very well and I think the difference between the values is probably related to temperature. The gains from the voltage conversion are dependent on panel temperature (because this effects Vmp). The ambient temperature for my panels in the eastern Mediterranean was considerably warmer than MaineSail’s test.

So It is important to realise that the gains are not high, but in a marine installation where there is little room to install solar panels the switch between PWM controllers and MPPT can be worthwhile in some cases.

Of course with high voltage panels the voltage conversion of MPPT controllers is essential.

[Tillsbury]

Mppt controllers can make series/parallel combinations work well, particularly if you need to use smaller panels for space reasons which is common on a boat. I ended up with two pairs of 120W panels, each pair in series (thus providing heaps of voltage and giving the controller plenty to do with thinner wiring), and each pair going to a small victron controller both connected to a ccgx. It happens on my setup that if one panel of a pair is unshaded it’s almost certain the other will be clear too, so I don’t get issues of one of a series pair shutting the other down. It also happens that the sun is likely to be mostly on one pair or the other, so one controller is thumping out power and the other struggling. Works well.

The ccgx is great, but is a boat-wide power controller and overkill for solar only. If you have shore power, a victron charger and inverter, solar controllers, and a generator then it gets better and better.

[CatNewBee]

I have a single 100A MPPT controller for 5 panels 330Wp each, nominally it would be good for 1450W, we use it with 1650W, merely because the panels are flat on the roof, and most of the time one is shaded by the boom, topping lift or mast, so it rarely hits 100A output. It has a good protection logic inside too.. No need for separate controllers. Panels are protected by string diodes against reverse currents.

[BigAl.NZ]

Originally Posted by gwbull

We have 2 panels wired individually to 2 Victron smart solar controllers with a Victron bmv 712 monitor. We have networked all components and can view (and correct, change, etc) quickly and easily on our iPhone or iPad. No need to jump thru hoops. All info is at our fingertips. We like this.
Just one remaining mystery — maybe a setting error — but only one panel delivers. The other has power we can see on screen, but delivers 0. Could be a controller problem maybe. But if we can correct this failure we’ll be quite pleased with the ease of this system.

I have the BMV712 - so by having the solar controllers networked to the BMV712 I can just connect to the BMV712 and that relays all the information from the solar panels as well?

[CatNewBee]

Originally Posted by BigAl.NZ

I have the BMV712 - so by having the solar controllers networked to the BMV712 I can just connect to the BMV712 and that relays all the information from the solar panels as well?

The BMV is an independent device, it can provide battery voltage to the MPPT SMART CONTROLLER to eliminate the voltage drop error on the controller poles when calculating the values for the charge profile. .

[CatNewBee]

The BMV does not show any parameters from the solar controller. It only measures the current (actually the voltage drop over the shunt) and the battery voltage. It calculates then all other values by aggregation over the time... (like Ah, kWh, kW, SOC...)

[The Sun King]

Not enough info in the question, so I will give a shotgun answer. If your controller is MPPT, a real one, then it is usually very efficient to wire in series up to around 150v. I do this on my home PV system, but on a boat, you have bothersome shading from masts and such, so wiring parallel is likely more efficient. If you do not have MPPT, then wire your panels parallel, up to the rated power. I assume here that you are using "12v" panels on a 12v system. "24v" panels can be used on a 12v system, but you'll need to use an MPPT charge controller to buck the voltage. 24v panels are cheaper/watt than 12 v and very efficient at collecting the power. My charge light comes on with the first pink rays of dawn.

[moseriw]

With 2 or more controllers you will face another problem. see the Victron DUO (btw. assistance from Victron does not exist. I believe Sterling is far better).

You have 2 Banks: 1 Automotive and one house so you connect The Stbd/Port DUO's to each bank.

DUO 1 decides to stop chargin completely to measure out if the battery is fully charged or not.

DUO 2 reckons that the battery has to be charged an rises to14,8V
and so on....


Technically I do not see a way to avoid the DUO's confusion and then, of course, malfunction.

And, of course, there is no believable statement from VICTRON.

Sayin: "Oh thats no problem it'll work" is certainly not enough.

[john007]

The principal difference is parallel or series. A totally different set of sums. I suspect that on the boat the batteries will be in parallel. 12 volts. Then you can then do the other calculations.