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How many Trina Solar DE15M(II)'s can I connect in series with MPPT 150/35?

I already have a new MPPT 150/35 Charge Controller and six Trina Solar (Tallmax) DE15M(II) 395-420W panels. The panel Voc is listed as a range (not a single value): 48.7 to 49.7v at 395 to 420W (respectively) at Standard Test Conditions and 45.9 to 46.7v , same power output range, at Nominal Module Operating Temperature. I live at 38.5375 deg. N. lattitude (maybe 60 miles north of San Francisco, CA as the crow flies). The Victron Energy MPPT 150/35 lists Max PV Voc of 145v start-up and operating conditions, 150v absolute max. coldest conditions. It seems like I can therefore just "squeek in" connecting 3 of the DE15M(II)'s in series, and have two of those 3-element strings in parallel going into the charge controller. The battery bank is 48v (eight 12v batteries, 4 in series, two sets of those in parallel). The panel short circuit current is 10.37 to 10.76 A at STC so that seems fine either way (3 x 2 or 2 x 3). Is this correct? Would 3 strings of 2 panels in series be better, safer, ...?


rcblasdell asked
rcblasdell commented ·

1 Answer

Mono 4a series panel vs Pany HIT

Panasonic have stopped their HIT panels, shame as I was going to fit a n250, just the right size for my van but then I found the Victron 4a series panels, the 175 and the 215.

the HIT were apparently famed for their ability in low light and cloud and I wanted to ask if anyone knew of comparisons with the Victron 4a series in this respect? Also I can’t find any figures relating to the efficiency of the 4a.

Can anyone advise please?

pusscat asked
wkirby answered ·

1 Answer

Choix du Parafoudre DC devant MPPT

Impossible de trouver dans les doc VICTRON quelle tension max peut supporter en particulier un MPPT 150/35 et un SmartSolar 450/200 (et tous les autres bien sûr). C'est une info nécessaire pour choisir un parafoudre de type 2 qui "écrête" à une tension inférieure à cette tension recherchée sur le MPPT.

lolei31 asked
lolei31 answered ·

3 Answers

Adding in occasional use panels

I have a 100w 12v panel on the roof of my camper, connected via a Victron SmartSolar MPPT 100V 20amp controller. I want to add an external portable 100w 12v panel that I can move around to face the sun better. I think I can wire both panels in parallel into the charge controller, and disconnect (via power poles or the like) the portable one when not in use.

Is there any danger in this kind of a configuration? Or am I looking at it incorrectly?

Thanks in advance!

eric-linxweiler asked
eric-linxweiler answered ·

2 Answers

VictronConnect App zeigt seit Installation 0W


ich habe letzte Woche meine Solaranlage angeschlossen. Ich habe einen MPPT 75/15 Laderegler und eine 12V Lithium-Batterie. In der App wird mir dauerhaft Spannung (V) angezeigt, jedoch kein Watt oder Ah. Woran kann das liegen, dass das Paneel nichts einspeist und somit anfängt die Batterie zu laden?
kann das an der Reihenfolge der Montage liegen? Ich hatte auch bereits gelesen, dass die PV Spannung 5V höher sein muss, damit der Laderegler anfängt zu laden.

janek-buss asked
jajaja answered ·

4 Answers

Solar Blankets and Charging Input for battery.

So recently I had an issue with my 4A charger for my deep cycle battery and found out that I’ve been using an underpowered charger for my 100ah AGM.
Ive purchased an ip65 15A from now on. As I’ve been informed that I should be charging my battery at 10% of the capacity of the battery. This raises another question for me.
Can someone tell me why it’s generally perceived as acceptable to use 200-250w solar panels for charging AGM Batteries, even though most of those panels would struggle to output 10A let alone 10% of a larger battery?

benny23 asked
Mike Dorsett answered ·

1 Answer

Bad performance af Bluesolar MPPT 75/10 with 40W of panels

I am struggling to find the cause of very bad performance of my sailboat 40W solar panel installation.

The controller is Bluesolar MPPT 75/10. There are 2 horizontal panels of 20W each, connected in parallel. The panels are Sunbeam Tough Flush T20F. According to data they are supposed to have Vmp=20.88V, Imp=0.99A, Voc=24.48V and Isc=1.19A each.

My gel battery is not full and needs charge. The last weeks there has been plenty of sun. I am in south of Sweden. However the max power seems to be only mediocre 4W and a typical daily yield is only 30-50 Wh. The panel current sum normally is 0.3A in full sun when the panels are not shaded.

The cable is 2.5 mm2 from the panels. I have checked all connections. I even tested another temporary cable just to be sure.

According to nearby weather stations solar radiation intensity is typically 960 W/m2 at this time of the year, which is not that far away from the test conditions 1000 W/m2.

According to the Victron calculator the panels should produce almost 150 Wh/day or a max charge current of around 3A. But my poor 30 Wh/day or max current 0.3A is simply so much lower that I am now frustrated. I was hoping for at least 100 Wh/d or perhaps even more. A max power of 25W or current of 2A was also in my expectations from this 40W installation.

With a Fluke 179 multimeter I have measured the sum from the two parallelled horizontal panels as Voc=21.9V and Isc=0.95A when in max sun at 13:00. That is much lower than the panel data, isn't it? As there are two panels Isc should be 2*1.19A=2.4A at perfect conditions.

My tests also reveal that one of the panels seems weak, as it only gives half the current than the other does. And its voltage seems lower than the other.

The solar panel producer Sunbeam says that the Victron controller is not good enough and wants me to buy theirs instead. They say that their controller starts at a much lower voltage difference and consumes much less power, They say it is better than the Victron, in what ways I don't know.

I have read various posts here on the subject, but it seems as everyone is getting much more out of their panels than I do.

Should I claim warranty on one or both of the panels?
Or am I simply expecting too much?
Or could there be a problem with the Victron Bluesolar MPPT 75/10 controller itself?

johwin61 asked
johwin61 answered ·

3 Answers

Cable fittings dont fit SPM040551200

Hi I just bought a SPM040551200 with Victron Solarcable L=5m/6sqmm MC4-M/F conn. (PV-ST01). The water tight cable box has fittings that are too small to fit that cable (with contacts removed.) What type of connection and cable am I supposed to use? The dealer I used is a certified victron dealer, so I thought they would tell me if something was wrong, when I mailed them before I placed my order.


mcdee asked

0 Answers

Charger for 2 x AGM 100Ah boat batteries?

I have a camping boat with 2 x 100Ah AGM batteries and a switch panel for 1, 2 or 1&2. Starter battery (1) and battery (2) for the fridge, Ipads etc. I want to be able to charge fairly quick when there is access to shore power, use solar when in nature and to keep batteries full when at harbour (no power there).

What charger is best for my setup? Thinking of these...

Blue Smart IP67 12V 17A

Blue Smart Ip22 30a/3

Blue Smart Ip65 25a

For solar this is my thinking. Connect this to both battery 1&2?

Solar panel 100W with regulator Smartsolar Mppt 75/15

In the future I’m considering changing battery (2) for a lithium if needed.

Im new here so any recommendations is greatly appreciated.

marcuslundh asked
shreeyash answered ·

1 Answer

How to charge one 12V and one 24V batteries with one solar panel?

Hi, on my boat I have a 12V LFP and a 24V LFP batteries.

I wonder if it is possible to keep them charged with one single 200W (29V) solar panel, and what equipment would be needed.


mporta71 asked
mporta71 commented ·

1 Answer

Can I use a common negative bus in a 4 MPPT & 4 PV installation?

Hi All. I'm going to install my set, having 4 100/30 each one connected only to a single 450W PV, in a 12v installation. This is already discussed in a previous discussion, and this approach is for the shadows managing and also for the cost and redundancy, beeing better 4 than 1 regulator.

I wonder if, in order to save cabling from 4 to 1, and routing and path (it is thin and strechy), I can connect all the PV negatives to a single 1 cable negative in the PV side, with a section 4 times AWG previuosly selected, and way this to reach all the regulators site, where I will spread again each negative to every regulator PV- input

Positive cables will run independiently , 4 .

Can be possible?

Is there any cons, apart from that if I added new panels I must to run new negatives?


combatdiver asked

0 Answers

2x 100/20-48v mppt for 4 panels or 1x 150/35

I'm dipping my toe into the victron world... I have roof space for 4 solar panels. I'm thinking 4xLongi 375W with open voltages of 41.1v. I was planning on using 2x 100/20-48v smart solar MPPT's and having 2 mini arrays of 2 panels. The roof gets good sun, but there is a tree which will partially block one panel later in the day.

Am I better with a single 150/35 mppt and wiring the panels up differently or even just having 3 panels in series not bothering with 4th?

My thinking might need correcting...

I weighing up whether 3 panels in series with an open circuit of 120ish volts will operate the charger longer for a 48v system than 2x2 panels with a max open circuit of 82v...

Also, by separating the panels on separate MPPT's and strings do I protect against the panel which gets shaded from dragging down all 4 panels if compared to them being on the same string/MPPT.

cost wise there doesn't seem to much in it.. Or is there a better setup entirely.

The system will be feeding...

Multiplus ii 3000VA 48v

2.4kw 48v plyontech battery (intention is to add more at later date)

Cerbo GX

It will be grid tied.

Really would appreciate some guidance

Many thanks.

ramblinglamb asked
Murray van Graan commented ·

2 Answers

Solar panel black

Hello, one of the squares on our solar panel is black whereas the rest are blue. Does this mean there is a fault? Would it be affecting our incoming watts?


emmakrieg asked
klim8skeptic commented ·

0 Answers

Is it possible to use the EasySolar II to charge an EV ?

Hello, Is it possible to use the EasySolar II to charge an EV ?

What I mean is just used it 'islanded' to change a electric vehicle directly.

Solar panels > EasySolar II > EV

myozone asked
myozone edited ·

2 Answers

PV voltage very unstable

I have a very unstable PV voltage coming from my 285W solar panel. The voltage is jumping between roughly 35V and 15V. This is quite new behaviour as before the voltage was kept more in the 35-38V region.


markbruin asked
offroadflow edited ·

1 Answer

Parallel solar array wiring configuration

I am trying to figure out the best way to wire my solar array. I will be running:

6 x 370W Trina solar panels with my Smart Solar MPPT 150/100 TR (Batteries are 24v). Photo attached of PV panel specs

Each panel has a max short circuit current rating of 11.37A. So I was thinking of running a 15A MC4 fuse for each panel. But the part I'm not sure about it how many cables I should run.

For example, Should I run smaller cables from each individual panel down to my electrical box, so I would have 12 cables (6 pos and 6 neg) running down to my electrical cabinet. (This seems like alot of cables...)


Should I join the panels into 3 pairs of 2 with MC4 splitters, so I would have 6 larger cables (3 pos and 3 neg) running down to my electrical cabinet


Another configuration?

The cable run from the furthest panel from the electrical cabinet is just under 10m. So obviously whichever way I go I need the cable to be large enough to carry the current (in this case at least 15A for one panel, due to fuse size) over that distance for however many panels are feeding it but also small enough to be soldered into an MC4 connector.

I know that in some cases people use like a junction box to join the panels, but I really don't like the idea of a box being on the roof in the weather to get moisture etc inside of it. I'd prefer them to all join in the electrical box which I am planning on doing.

Sorry for the long question. Just trying to find out the proper way to do things. If that's completely different from what I'm imagining, I'm willing to embrace it.

Brandon asked
Brandon commented ·

1 Answer

2 x100w panels and a 75/15 blue smart controller

My out shows 10kwh, I've no idea what normal should be? any help

feggers1316 asked
kevp commented ·

0 Answers

solar panel

Good day, can i let a solar panel unconnected on a roof for a couple of days without damaging it ? i need some time to install my setup before connecting them. Thanks.

yannd asked
yannd commented ·

1 Answer

Solar panel suitability question

I have bought a BlueSolar PWM Duo-LCD-USB charge controller to charge my 220ah leisure battery bank and also the vehicle battery on my motorhome. Could anyone tell me if these solar panels are suitable for my system please? I would be looking at buying 2 of them. The manual for the charge controller says to use 36 cell panels but these are 54 cell.

frontbackside2side asked
tozz answered ·

1 Answer

2 strings panels at an angle

Trying to improve power from an existing roof installation.

We have an EasySolar II GX, which has a Multiplus II 48/3000/35-32 inverter plus a SmartSolar MPPT 250/70 solar controller.

We have 6x 320 W Trina Honey panels mounted on the roof of an ISO 20' (6m) shipping container. Because of the space constraints of the container roof, they are oriented about 20 degrees east of the meridian so get morning sun but lose it in the afternoon.

This is not producing enough power, so we have bought another 6x the same panels. We have 2 more 20' shipping containers at about 90 degrees from the original container (close enough that you could consider it one big roof).

Conventional wisdom seems to be that the new panels must be oriented exactly the same imperfect angle (azimuth and elevation) as the existing panels. Is there a better alternative?

I have seen some comment that two strings of panels back to back, facing respectively east and west, will not 'interfere' with each other so you effectively get separate morning and afternoon charge sessions from them.

Is that a better solution? How about having the two strings at 90 degrees, so facing respectively 45 degrees east of the meridian and 45 degrees west? What is the theory around this? What are the EasySolar's constraints?

spicedreams asked
seb71 commented ·

2 Answers

Add more battery or more panels?

My system is ~3 months old and has been working well through our NZ summer, but, on cloudy days the battery voltage drops into the <50% SoC range. With winter coming up, I am trying to prioritise between adding battery capacity or adding panels. My sense is that it's 'now or never' for battery because I hear that new batteries adopt the 'age' of existing batteries.

My question is, what information produced by the system should lead me to decide on more batteries or more panels? Hoping someone can help...

My off grid system comprises:

  • 6x 320 W Trina brand panels (roof mounted so point more east than optimal)
  • 3 kW Victron EasySolar II GX (seems to consist of:
    • SmartSolar MPPT 250/70 -Tr charge controller
    • Multiplus-ll] 48/3000/35-32 inverter/charger
    • connected to VRM about 1 month after install )
  • BMV 700 battery monitor (no VE.Direct connection- should there be?)
  • 4x 12V 260 Ah AGM batteries in series

Our power draw averages around 250 W 24x7 plus 30 W for the EasySolar II GX itself. VRM says over last 30 days, consumption has been 171 kWh and production 192 kWh. I haven't found anywhere that VRM (or the remote console) tells me "but production would be higher by X if you had more storage".

Hope someone with more experience can help.

Thanks, Graham

spicedreams asked
Eduard answered ·

5 Answers

Maths on mixed solar panels

New to the forum and after some advice on my maths on a possible solar set up on my upcoming camper build. Due to roof size I’m looking at mixing panels. Plan is for Victron blue solar mono panels using two 175w and two 55w. The mppt will be feeding into a 48/5000/70 Multiplus-2 and 9.6 kWh pylontech battery bank.

2 x 115w in series = 38.8v @ 9.03a

IMPP 9.03a

VMPP 19.4v

VOC 23.7v

ISC 9.89a

2 x 55w in series = 37.6 @ 2.94a

IMMP 2.94a

VMPP 18.8a

VOC 22.9v

ISC 3.22a

Then wired in parallel coming out to 37.6v @ 11.97 = 450w (a loss of only 10w)

Is this maths correct or have I missed something?

Then as to which MPPT -

2 x 55w panel ISC 3.22a

2x 175w panel 9.89a

+20% =31.36a

2 x 55w panel VOC 23.7v

2x 175w VOC 22.9v

+3.5% =96.46v

So a Smart solar 100/50 will be correct?

Looking forward to any advice, help.




mark-m asked
mark-m commented ·

4 Answers

Warum wird Strom aus dem Netzt entnommen?

Hallo Leute ,

mein ESS System funktioniert soweit sehr gut und zuverlässig:

Multiplus II 3kw

Color Control

2x Pylontech us2000B

Zähler netzt und Zähler pv

Nun kommt es immer wieder vor das Nachts oder am Morgen Strom aus dem Netzt entkommen wird obwohl der Akku noch mehr als 10% hat(10% ist mein Soc) . Wie auf dem Bild zu sehen ist wird Strom aus dem netzt entnommen obwohl der Akku 30% hat und zudem wird sogar noch aufgeladen.

Teilweise habe ich beim Laden den Eindruck das Victron nicht richtig misst oder Werte fürs laden als Verbrauch annimmt ???



rb994 asked

0 Answers

Adding second solar array in parallel doesn’t double output but stays same

I added a duplicate array of 4 x 200 watt panels in parallel to my Victron 100/30 controller. My first array is wired in series and would produce about 420 watts on a sunny day. I figured I would add another 4 identical panels in series as a second array and then wire the two arrays in parallel. I assumed I would double my output but it stays the same. I can disconnect either array and get the same result. Am I doing something wrong or is this normal? I know the voltage and amperage are under the 100 volts and 30 amps of the controller.

surfamj asked
wkirby commented ·

3 Answers

Japanese RV Build— Stuck on Bulk / Configuration Review

Hey Folks,

Appreciate you stopping by. I’m new to this area, but I’ve done a bit of research to solution for various other issues.. That said, i now am a bit stumped and would appreciate some help.

Background on my set up:

  • 180w NewPowa solar panel x2 (Run in parallel & Fully tested before and after install)
  • Victron MPPT Controler 100| 30
  • Battle Born LiFePO4 (lithium) 100Ah 12v battery x3 (total 300Ah) run in parallel
  • Victron BMV 712 Smart Monitor

Configuration for Victron systems:

Pictured below are my key setting configurations for my set up. I used the manual as well as some other threads to determine my settings.

Settings for the 100| 30 Controler :


Settings for the 712 Smart Monitor:



  1. Based on my Whole electric system, does my configuration above seem to be accurate or are there pieces that I should re-evaluate?
  2. Today and yesterday (during the day) my system has been stuck in ”Bulk”, which from what I read, means that the batteries are low and the system will bring in large amounts of power to charge them. The issue is that the batteries are very close to being fully charged. (below is some data from the app showing that I’m stuck on float) . I think its important to point out that I have been able to put a load on this and see my numbers and battery voltage adjust but I continue to stay in “bulk” . What could be causing this?



  3. Possibly related to #2, today during a sunny day, my solar panels were barely bringing in any watts 30-50w range, while in bulk model. My battery on the monitor was at 95% or 13.4v but it didnt seem like it was going up at all. Any reason why this was happening?

Any help is greatly appreciate. Happy to provide more details around certain aspects.

Here are some additional data grabs...

Below is a picture from the monitor today while having a slight load on it (fan, heater, lights):


Here’s a picture of the van when I bought it.. It’s changed a lottttt since then.


coleinavan asked
jvan commented ·

3 Answers

17v vs 18v Vmax panel with 100/20 MPPT

Hi all,

I am building solar system for a small Airstream trailer with very limited roof space, my goal is to get > 200w panels. Due to roof top space limitation, My panel selection is limited to the 2 options below.

1. Renogy 100w + 50w + 50w (Voc: 21.6, Vmax: 17.9) total 200w

2. Newpowa 75w x 3 (Voc: 20.3, Vmax: 17.0) total 225w

I am leaning towards #2, as it offers more watts and having the same panels are always a plus.

But since I need to install them in parallel due to roof top A/C unit shading, I am concerned that the ~1v Vmax drop in Newpowa might not work well with my Victron SmartSolar 100/20 SCC and LiFePo4 battery bank (13.4v fully charged)

According to SCC manual the

Voc needs to be 13.4+5 = 18.4v for SCC kickoff charging

Vmax needs to be 13.4+1 = 14.4v for SCC to staying in charging

This is very close to the spec of Newpowa panels (20.3v, 17v) and I am wondering if it's a bad idea to use these panels - panels won't be able to supply high enough voltage for SCC on a cloudy day? The Renogy panels would have a more comfortable margin and should be used instead?

Thanks in advance!

hovr asked
jvan answered ·

2 Answers

can i mix panels with 2 def isc amps

what happens when you connect a panel with 8.8 amps to a panel with 8.45 amps,, i have 12 with a isc of 8.8 and i have 16 panels with a isc of 8.45 i have the 8.8 in sets of 3 for a 135 volt,, and i have the 8.45 in sets of 4 to get 148 volts,,i know the 148 gets taken down to 135 i checked that what i don't know is the amp part, will the 8.8 get taken down to the 8.45? I'm using the 250/100

kevin-b asked
klim8skeptic answered ·

2 Answers

Solar pannels giving low energy

Hello everyone,

Think there is an issue with my system. I have 4 solar pannels like this, connected in series.


They are connected in series on my victron


and it's connected to 2 batteries agm 12-170.

However, even with super sunny days the solar pannels only give very little energy and i don't understand why.


Like, this is a picture right now, with full sun on my pannels (they are positioned correctly). Why are they only giving 112W ??

I already checked if the wired are plugged in correctly and tried to read the victron manual many times, but i am an electricity noob.

If you know what's happening and how i could fix it i'd be so happy. This has been going on since i moved in here...

Thank you !!

esmeralda-wirtz asked
esmeralda-wirtz commented ·

1 Answer

SmartSolar MPPT 100/20 and two Panels


i am running the mppt 100/20 together with following solar panel since one year for my pool-pump.

The mppt/20 loads a 12V battery and a step up converter provides 230V for the Pump and in future hopefully also for the "Pool Heater".

The Panel has following specification

Nennleistung: 360 Wp
Toleranz ca.: + 3%
MPP-Spannung: 39,00 V
MPP-Strom: 9,24 A
Leerlaufspannung: 47,50 V
Kurzschlussstrom: 9,71 A
Zellen: 156x156mm, 72 Monokristalline Zellen, Class A

Is it possible to connect a second identical Panel to the mppt100/20 and can the Smart Solar Charger handle it? My plan is to connect a"Pool-heater" and therefore i need a bit more power :-)
How should i connect them? In row or parallel?

Thank you very much for your support in advance.

Best regards


vommatthias asked
seb71 commented ·

2 Answers

ovesizing solar panels

i’ve victron smart solar 150/100

i’ve 6 solar panels 2 series, 3 parallel

if i use them both will the mppt controller handle it ?

(i mean will it handle 100amps current and cap there or will burn ?)

according to calculations in perfect conditions there might be 130-140 amps @ 12v from panels.

i’m ok if it will handle it by capping it 100amps

ers asked
JohnC answered ·

3 Answers


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