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series connecting panels with different wattages

On our sailboat I am in the process of installing three Solbian SP panels, a pair of 118W and a single 144W, each with a separate Victron 75/15 MPPT controller (because of the usual boat shading problems). It occurred to me that on an overcast day, it would be pretty simple to reconnect the panels MC4 connector leads to put them in series to a single controller (one of which I would replace with a larger model able to handle the output of all three panels).

I've read where different power panels could be problematic. How big a difference would cause a problem. Should I keep the idea but limit it to the two identical panels?

oceanwolfe asked
oceanwolfe commented ·

3 Answers

How long would it take my 20W solar panel to recharge my 12V 9Ah Lifepo4 battery?


I would like to know if my Victron 20W solar panel be suitable to power my Invicta Lithium 12V 9Ah Lifepo4 Battery.

Victron solar panel specifications:


Lifepo4 battery specifications:


Power manager (MPPT):

I would also like to interface the solar panel and battery using my Victron SmartSolar MPPT 75/10 solar charge controller.

The reason why I ask is to get an understanding of:

1. Compatibility between all three components, &

2. An approximate or average on long would it take to charge up the battery, if the battery was in a depleted state (at a cut off voltage of say 10.5v).

Your help would be much appreciated. Thank you.

samuil asked
kevgermany commented ·

1 Answer

Victron Energy Solar Panels 20V 270W Poly


I see Victron Energy Solar Panels 20V 270W Poly advertised under 3 product codes: SPP042702000, SPP042702002 and SPP042702003 with the designations 4a, 4b and 4c respectively . What is the difference between these products?


jmans asked

0 Answers

adding a solar panel of different wattage

Hello, I have an off grid system that is using the Victron MPPT 150/85 solar charge controller. On top of our RV we currently have four 300W Renogy Watt Monocrystalline Solar Panels. I would like to add another panel or two but Renogy is no longer making the 300W panel. They are now only making a 320 Watt panel. Can I add that to the array or because it is a different wattage would it be a problem? Would it be better to go with a different brand and stick to 300 Watt panels? My current 4 panels are running in Parallel going into the MPPT 150/85 solar charge controller. Please advise! I need more solar to run the Air Conditioner this summer. Thanks

overland asked
overland answered ·

10 Answers

Charging 2 battery banks from one mppt?

My sailboat has 2 4D flooded lead acid batteries on an 1-2-both switch without an additional dedicated starting battery. I think this effectively makes each battery a separate “bank” in the vocabulary of this forum. We normally use the #1 battery on odd days and #2 on even days, always charging both with the 100 amp engine driven alternator when under power and occasionally when at shore power. Our shore power charger has isolated outputs to charge multiple banks. We primarily weekend on the boat. During the week it is on a mooring without shore power. I want to add 2 x 50W solar panels on the dodger to ensure batteries are well charged when I arrive for the weekend. For occasional 1-2 week summer cruises, I plan to add temporarily mounted 2 x 100w panels to try to minimize or eliminate the need to run the diesel or portable generator to charge while we sit an anchor for multiple days running the fridge And all other comforts of home. I plan to run all the panels in parallel since there is always a shadow risk on a sailboat. We always switch the battery switch off when leaving the boat. I bought a smart Solar mppt 100/30, but now realize that since the batteries are set up as two separate banks, simply hooking up the single output to one of the batteries will not work as intended and hooking up to both batteries effectively combines the batteries into one bank where one battery will charge the other. Any ideas? The simpler the better, please. Thanks from a novice.

bluemoon2010 asked
bluemoon2010 answered ·

2 Answers

Absorption voltage too high



Hello :)

i have a MPPT smart solar 75/15 installed to a 120 AH battery.

Has been functioning good for 1 year.

Today suddenly the Absorption Voltage was too high. It was up to 14.95. for many seconds until i intervened.

In the settings i have 14.7. I even tried lowering it to 14.6. But did not change anything.

How can that happen?

I dont know how high it would have gone if I had not put something on the panel.

I disconnected the MPPT from the battery and connected it again. Then it was Ok and the charger only went up to 14.7.

Did someone have the same problem?



jonas211 asked
jonas211 commented ·

1 Answer


Good afternoon, I'm in a difficult situation. I have a 24 volt solar panel, I want to connect the batteries in parallel to save 12 volts, since I already have a very good inverter for 12 - 220 volts.

Will the BlueSolar MPPT 100/50 controller (for example) work in such a system? And in general, is it possible that the panels are 24 volts, and the batteries are 12 volts?

And one more question, I have seen many controllers with the ability to connect a load, but the output voltage of the load is not indicated anywhere. Does it depend on the voltage of the panels, batteries or the controller itself?

weltverloren asked
kevgermany commented ·

4 Answers

Sizing MPPT for 5 x 550W 24V solar panels for a 12V battery system


I am putting together a solar charging system for my 12V battery on a boat.

Option1: 5 x 550W (24V) solar panels, connected in parallel, a total 2750W => charge the 800Ah - 12V battery bank.

Option2: 6 x 200W (12V) Solar panels, connected in parallel (3x2) for 1200W => charge a 800Ah - 12V

- What is the size of the MPPT that I can use with the solar panels?


james-nguyen asked
james-nguyen edited ·

1 Answer

2 of 3 MPPT regulators died

The other day a costumer of mine noticed that the PW power have decreased significantly.
They system are 2-3 years old, so stuff should not start to fail already.
I checked the VRM logg and noticed the following:


Note that regulator 1 voltage reading looks normal, but number 2 and 3 are more square and strange - they are all feed from the same battery.

It cant be the DC fuse to the battery?? or? but they read the voltage in the night.


Any one who have any ide what it cant be?
If course there are 4 hours drive to the site, so any ide for remote checks are appreciated.

There are a CCGX on site, with full remote access from home.

jimmy-henningsson asked
Alexandra edited ·

2 Answers

Can DC-coupled MPPT feed directly into power need of ACout, or only be used to charge batteries (no ESS)

I have a solar panel (340W) with a Bluesolar MPPT (DC-coupled), BMV-700, Cerbo GX and Multiplus. The ACout of theMultiplus is attached to a separate network in the house which is only attached to this ACout (not mains feedback). The Multiplus can use the ACin or the inverter to provide power to this network.

Ideally, I would like to keep the batteries fully charged and prioritise the solar power to feed into that separate network (i.e. use solar power until the load exceeds the solar power and then complement with ACin or if that is useful to add power from the batteries) and only switch to the batteries/inverter during power failure.

For what I read on the Victron website, this could be (easily) achieved by installing an 'assistant' IF I would feed back into the net. However, I can not feed back into the net.

So my question is, how to achieve this situation (solar power complementing net power, having priority)?

I configured a set-up similar to described by Edphonse using the virtual switch, but it feels like a sub-optimal configuration.

Currently I use the virtual switch to use the Multiplus as inverter until the battery voltage drops to 25V (then use ACin), or the load on the ACout exceeds 300W (and then the Multiplus also charges the batteries if needed until bulk is completed).

This sort of works but is clearly a 'hack' and power is lost by charging and inverting. Edphone also importantly notes that using this approach the batteries and Multiplus will wear quickly.

So effectively my question is whether I can use the solar power to feed into the ACout network without needing to discharge the batteries (I read in one of the posts that there is an option to keep the batteries at fully charged state, but then also the solar power input seems to be throttled back).

Or, perhaps the current set-up is still usable, but I would need to increase my solar power capacity (which is admittedly quite low) so that it would always exceed the normal load on the ACout. That is assuming that the solar power will be used for direct power and not only to charge the batteries.

harro asked
JohnC answered ·

1 Answer

Pwm light 20a no longer in taking solar

I have a 200w solar panel connected to my pwm light 12v 20a and it was working fine. The light was flashing indicating power coming from the solar panel and into the battery but now the solar input light is showing nothing even though I know there is 19v coming from the solar panel. At one point the battery did run flat and I thought maybe it turned itself off so I disconnected it and reconnected the cables and still nothing. When change the setting I get an 'ff' flash after the setting has been selected. Not sure what this means as it is not in my one page instruction sheet I got with the controller.

zac imhoof asked
rscottf1 edited ·

3 Answers

solar panel

hello everyone,im a camping enthusiast.

can you guys recommend a solar panel for my camping or road trips?


thera asked
thera commented ·

0 Answers

Change MPPT Tracking Refresh Interval

We collect data from our Victron system and store it for analysis. Here you can see the power generation curve from our rooftop solar panels, connected to a Victron 100/50 solar charge controller.


As you can see, every 10 minutes, the power drops off dramatically. I'm guessing this is the solar charge controller sweeping to find the Maximum Power Point.

Each of these "sweeps" takes ~33 seconds to complete, and during this time, power production decreases dramatically - the middle drop on the chart above is ~158W to ~120W average or so (about a 25% decrease). Power production after the sweep appears almost completely unchanged - looking at the PV input voltage, it reduced by ~0.18V (from 34.50V to 34.32V).

Treating this as a duty cycle and averaging over time, a 25% drop for 33 seconds every 10 minutes corresponds to roughly a 1.4% total drop in output.


  1. Am I understanding the purpose of these drops correctly?
  2. Would the MPPT adjustment provide >1.4% improvement to output during the next 10 minutes?
  3. Is it possible / does it make sense to make the interval between these event adjustable - i.e. a user setting to change it?



Matt Knight asked
custom answered ·

6 Answers

Combining different size solar panels on camper

Hi all!

I currently have 2x 175W solar panels from Victron on the roof of my camper (Vmpp = 19.4, Impp = 9.03, Voc = 23.7, Isc = 9.89). I have them in series connected to a 100|30 MPPT from Victron. I have limited space on my roof but would like to extend my grid with one or two 55W panels (Vmpp = 18.8, Impp = 2.94, Voc = 22.9, Isc = 3.22). What would be the best way to connect them to my grid?

I understood that It is not advised to mix different panels - especially in series (high-efficiency loss), but parallel should work (with only a slight loss), right? Or am I missing something? Could you help me sort out the right method in case of:

  1. 2x 175W + 1x 55W
    Can I put all the panels in parallel and still run the same MPPT controller, or do I need to put the single 55W panel on its own controller. If so, which one should I go with (hopefully able to use with the same app).
  2. 2x 175W + 2x 55W
    Should I parallel them all or serie-parallel (175Ws and 55Ws separated) and run them on the same MPPT controller, or do I need to run both sets from their own controller? If so, which one should I go with (hopefully able to use with the same app).

I highly appreciate your help.



durovenia asked
kevgermany commented ·

1 Answer

Victron mppt power drops

Hello, can anyone tell me what all these power drops are on my victron mppt, this day had no clouds so it should be a smooth line but it has loads of drops.


alex435 asked
Stefanie answered ·

1 Answer


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