One controller or two?

[n2climbing]

I'm about to install four 140W panels in parallel on the roof of our catamaran. I asked advice on this topic from Just Catamarans. They advised one controller and said that is the way they typically set up solar charging systems. I am going with a Victron Blue Solar MPPT 100/50.

[Bleemus]

Originally Posted by n2climbing

I'm about to install four 140W panels in parallel on the roof of our catamaran. I asked advice on this topic from Just Catamarans. They advised one controller and said that is the way they typically set up solar charging systems. I am going with a Victron Blue Solar MPPT 100/50.

Are they 12v panels with a Voc around 22v? If so you will see your voltage around 16-17v in full sun. Be aware that the Victron will require 5v over battery voltage. Better off with two SmartSolar 100/30 units and wiring two panels in series per unit to get maximum MPPT benefits.

[n2climbing]

Solara S560M43 panels. Per spec sheet - voltage: 24.3, Voc: 29.5.

[john61ct]

That will be fine.

Note that the "more, smaller SCs" is not yet a mainstream idea, since traditionally costs were prohibitive.

[Bleemus]

Originally Posted by n2climbing

Solara S560M43 panels. Per spec sheet - voltage: 24.3, Voc: 29.5.

That should work fine then. I have four 140w 12v panels and just upgraded.

[jbinbi]

Got 2 smartsolars 100/20s for $160 each on amazon. now need to figure out if I just use my phone, or do i get the mppt controller, or battery monitor.

I am also going to get an inverter charger, so I will need the remote to work the inverter and probably the monitor. Don't think i will spring for the controller.

The color display that runs and shows all is $500. Too much.

[MikeFergie]

Just changed from 2 x victron bluesolar 100/30 controllers to 1 x victron 100/50 controller but I left one of the 100/30 controllers in place in case I need it one day and took the other one out.

Why ?

Simply the new controllers are bluetooth and by combining both panels I get the “full “ picture of total Kw hours per day

With 2 x345w sunpower panels I am getting 2.67KWh per day and over the past 30 days a total of 84KWh.

[kadiddle]

I would like to comment only on the concept of multiple MPPT controllers. A little over year ago we bought a new 5th wheel camper and we do a lot of "off grid" camping with no hookups. We wanted a robust solar system that would take into consideration the fact that one or more of our solar panels would often be shaded. The answer for us was to use one MPPT charge controller for each panel (2- 285 watt panels plus one 100w portable, one more portable can be added to this controller). We use 3, non identical controllers from Blue Sky Energy along with one of their IPN Pro Remotes. All controllers are hooked up to the IPN (very easy) from where all programming is performed and all controllers act like one controller except that each is able to put out it's maximum without getting dragged down by shaded panels. The results were quite good. We get shaded panels on most outings but the whole system seems to really maximize the output. This also allows you to use solar panels of different size, which can be an issue if the size you have is not available later when you want to add, or it let's you shop for the best deal on panels with no regard to exactly matching existing panels.
I recently saw a Catamaran for sale that used multiple Blue Sky Controllers, so it must be appropriate for boats. When we buy a boat, we will likely go this route again. Oh, btw, the Blue Sky products are very affordable and we have not had one single glitch in the system despite the fact it bangs around on rough forest service roads with regularity. Blue Sky also has a remote connection module through which you can control your system wirelessly, even over the internet from distant locations.
I have no affiliation with Blue Sky, just a happy customer, if anyone has any questions about this type of setup, just pm me.

[Longkeel]

Originally Posted by jbinbi

I have 2 285 watt panels, currently with 2 inexpensive $99 mppt controllers. Running in parallel. 12v system.

I am buying some victron equipment, and was also going to replace the controllers. I can put the 2 panels in parallel to a 50 Amp controller, or get 2 30 Amp controllers.

Both my old controllers work. Any reason to get 2 controllers from an electric respective?

I have just completed the very same task two weeks ago. I sought advice on one vs two controllers to service 4 x 160w panels installed in two arrays on a catamaran (total 640W). I already had 1 Victron 100/30 on board but was leaning towards a single 100/50. I was advised to go with two smaller units over one big one.
I was careful to include a bus bar directly adjacent the two units to ensure consistent voltage reading from a single cable to the house.
IIhave been monitoring since install to see performance.

The system has delivered 40+ amps at times (as expected) which confirmed that the combination was not limited to 30 amps. Tick.

My initial and main concern was around one array raising the voltage of the house, thus making the other mppt under deliver. This currently occurs with my two balmar alternator regulators which is a pain and a whole other topic...

Results to date. I have not been able to get the house to 100% charge as by 2pm the system goes into float at 80% charge. There is still plenty of sun at this time but the controllers govern the charge back to a float level.

I am yet to understand if this is an algorithm issue or an issue because of the two controllers similar to my balmar issue...

[john61ct]

Get into the settings and extend Hold Absorb Time.

[Longkeel]

Originally Posted by john61ct

Get into the settings and extend Hold Absorb Time.

unfortunately not an option in the Victron settings, only the maximum absorption time can be modified. The absorption duration is a function of the battery voltage reading when the sun hits the panels in the morning. The only other thing I can think of is the battery monitor settings. I have a xantrex monitor and will check to ensure the float voltage settings on the monitor match the solar controller float voltage. Head scratching to continue..

[noelex 77]

Originally Posted by Longkeel

Results to date. I have not been able to get the house to 100% charge as by 2pm the system goes into float at 80% charge. There is still plenty of sun at this time but the controllers govern the charge back to a float level.

The first thing to check is if the Victron units are going into float too early, or if the battery monitor is reporting the charge state as too low.

The best way to do this is look at the battery return amps when the controllers drop down to float. Battery return amps is the current entering the battery, not the current produced by the solar panels. Your battery monitor should display this net current, but you will have to manually note the value as the Victrons drop to float.

Ideally this should be done over charge cycles. This number together with the total battery capacity (in Ahrs) will indicate if the Victron units are entering float at an appropriate point.

[ReneJK]

Originally Posted by MikeFergie

Just changed from 2 x victron bluesolar 100/30 controllers to 1 x victron 100/50 controller but I left one of the 100/30 controllers in place in case I need it one day and took the other one out.

Why ?

Simply the new controllers are bluetooth and by combining both panels I get the “full “ picture of total Kw hours per day

With 2 x345w sunpower panels I am getting 2.67KWh per day and over the past 30 days a total of 84KWh.

Largely the same system I just upgraded to



2x 335Wp BenQ (Sunpower) panels with a victron 100/50 smartsolar controller (the smartsolar was actually cheaper than buying a bluesolar + dongle)



2.67 KWh/d is impressive ! I hope I get similar results from my system , that would certainly be enough to keep the bank full and provide extra for fridge/freezer/watermaker

[Bleemus]

Originally Posted by Longkeel

unfortunately not an option in the Victron settings, only the maximum absorption time can be modified. The absorption duration is a function of the battery voltage reading when the sun hits the panels in the morning. The only other thing I can think of is the battery monitor settings. I have a xantrex monitor and will check to ensure the float voltage settings on the monitor match the solar controller float voltage. Head scratching to continue..

Set maximum absorption time to 15 hours or similar. They should go all day until they hit float.

[noelex 77]

Originally Posted by Bleemus

Set maximum absorption time to 15 hours or similar. They should go all day until they hit float.

See post #26.

A slightly longer absorption time is better than too short, but I do not think this is a good idea, especially with more sensitive batteries like gel.