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Sizing advice MPPT 100/20

Looking at upgrading my RV solar to a 3 panel system on a new MPPT 100/20. Existing is 2*100W on an older controller. The older panels are discontinued so I am purchasing a 3rd panel that is not identical. Battery bank is dual 225Ah golf cart (in series = 12V)

New system would be:

2x Renogy 100W Panel modules
Voc 22.5V
Vmp 18.9V
Imp 5.29A
Isc 5.75A

1x Renogy 175W Panel module
Voc 21.6V
Vmp 18.1V
Imp 9.67A
Isc 10.31A

I've calculated these 3 panels can be run in parallel with only a 2.68% loss due to the difference in panel specifications. Panels will need to be individually fused due to the max fuse rating in the event of a short.

The updated array will output 365W at 17.95V @ 20.33A.

The Renogy calculator shows it's 129% oversized. Should be a good amount due to primary usage in the northern hemisphere, and they will be flat mounted.

My primary concern is: I've calculated the array short circuit (5.75A + 5.75A + 10.31A) = 21.81A. This number is tripping me up with regards to the 100/20 recommended max short circuit.

Does this prevent me from using the MPPT 100/20? Do I need to be looking at the MPPT 100/30?


Cody Watkins asked
ahtrimble answered ·

2 Answers

Newby Needs help with components choice.

Hello, all new to this, but I have solar panels and I have batteries.

What victron components do I need to build a 3fase system for 18000Wp solar panels combined with 70 KWh of battery storage?

thanks in advance.

rpvanhal asked
pip895 commented ·

1 Answer

Series+parallel 2 or 1 strings easysolar 260/70

I have 3 longi panels 370w, with 2 ja 380w on one string, the other 5 ja 380 all 7 ja are same, longi

Model: LR4-60HPH-370M

The amps and v differ and have a shokty diode after these 3. All 10 face same south direction, all shade free. The easysolar 48v 250/70. Why does the array need to be in 2 strings not 1 as it joins to 2 poles at inverter?

I suspect it has to be 2, should it be parallel

With 3 slightly mismatched or series? Or is there any other option?

If parallel each string 32a/200v can i use single 64a for current just before inverter?

Andrew asked
Andrew commented ·

1 Answer

Appropriate MPPT for 4x panels on 24V system?

My question is that I'm not sure what setup would be best if I have 4 of the following panels:

The online calculator suggests at 2S2P I should be using a 150/70 for a 24V system.

I have bought a Cerbo, and would like to connect the solar controller to it, is there a particular type (E.G Blue solar/Smart solar) that I would need for this?

Thanks in advance - I'm new to all this stuff, I figured it's best to ask those who know rather than make a costly mistake.

sean-cattee asked
kevgermany commented ·

3 Answers

Best mppt for my array

Hi, I have a few panels, of different sides. Which mppt should I use?

mvader (Victron Energy) asked
nesswill answered ·

3 Answers

Solar Panel Upgrade OffGrid

Hello Community,

I'm thinking of upgrading my off-grid system

Right now, i have the following system working 24/7.

  • MultiPlus-II 48/5000/70-48 – v475
  • BlueSolar Charger MPPT 150/60 rev2 – v3.07
  • Cerbo GX - v2.90~24
  • 2 x Pylontech US2000C Plus 48V
  • Q.Cells Q.PEAK DUO XL-G9.3-455w
    1. Vmp – 44.61V
    2. Imp – 10.20A
    3. Voc – 53.22V
    4. Isc – 10.67A

Panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 1820.09W
  • Max power voltage (Vmp): 89.22V
  • Max power current (Imp): 20.4A
  • Loss: 0%

Option to upgrade my sollar input:


  • 2 panels in Series = 1089.99W (Vmp): 82.7V - (Imp): 13.18A
    1. Vmp – 41.35V
    2. Imp – 13.18A
    3. Voc – 49.60V
    4. Isc – 13.86A

All identical panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 2777.07W
  • Max power voltage (Vmp): 82.7V
  • Max power current (Imp): 33.58A
  • Loss: 4.57%


  • 2 X 2 panels = 2179.97W (Vmp): 82.7V - (Imp): 26.36A
    1. Vmp – 41.35V
    2. Imp – 13.18A
    3. Voc – 49.60V
    4. Isc – 13.86A

All identical panels wired in SERIES, then all series strings wired in PARALLEL:

  • Max power output: 3867.05W
  • Max power voltage (Vmp): 82.7V
  • Max power current (Imp): 46.76A
  • Loss: 3.33%

What do you guys think is the best solution to maximize the current system.

Cheers for all the opinions.

OxyFly asked
JohnC answered ·

1 Answer

How much oversizing is too much?

Hello everyone!

I am a newbie, currently i have an offgrid system in a cabin with 4 320wp solar panels with a blue solar 150-35. 48 volts, 4 x pylontech us2000c.

During 3 months of winter i have bad shading because of a tall hill nearby, so mostly indirect lighting. Unfortunately is the only option, no grid nearby.

I ordered 12 jinko solar 420wp (37.96Voc, 14.01Isc). I want to make 4 series x 3 in parallel.

When i checked "oversize 135%", Victron calculator recomended me my exact charger, 150-35, and it said 253% oversized.

I ll be happy to keep using it, but how good this is for my system? And what charger do you recommend instead?

Thank you!

sylk asked
nesswill commented ·

5 Answers

How to wire panels to 150/100 controller

My friend has a solar array of 20 x 200w panels and they feed through a 150/100 controller with a 5000w Multiplus and a 750ah wet cell battery.

We live very remote and I would like to help him understand how the panels should be configured: should they just be series or series and parallel.

Can someone give advice on how best to utilise this panel array. Is the one controller adequate or should it be different and if so how.

mirriulah asked
love2learn edited ·

4 Answers

Is my solar panel sufficient for my power consumption?



Would you be able to tell me if my solar panel yield is suitable based on the consumption readings? Am I correct to assume today I consumed the exact amount of power my solar panel yielded? It is summer here in Australia I am just worried about winter.

My battery is 9Ah LifePo4 and my solar panel is 50W.

Kind regards!

samuil asked
albert commented ·

2 Answers

How manny panels on a smart solar 450/100


We have a question about the Smart solar 450/100-TR.

How manny panels can we put in series/parralel on this device?

The panels that we are going to use are the Hyundai HiE-S395VG.


Currently this is the setup

3x Multiplus 48/5000-70 (3phase configuration)

4x Pylontech US5000

AC coupled PV installation (3phase inverter) on AC output 1

melchior-sohilait asked
melchior-sohilait commented ·

4 Answers

Help selecting appropriate mppt current rating.

I have purchased a 12v 130ah lead carbon gel deep cycle battery for my VW Crafter camper-van. Apparently the max charging current on the battery is 25 amps.

I have 5x 385w mono panels and 1 x 325 watt mono panels.

If I use a 325 watt panel to charge a 12v battery the charge current would be 27.08 amps which exceeds the max charging current for the battery.

So there are two options:

1 - Go and buy a 250 watt panel that will produce 20.83 amps in optimal circumstances, then buy a 20 mppt controller.

2 - Use the 325 watt panel with a 20 amp mppt controller knowing that the controller will limit the max output current to 20 amps. We know that a 325 watt mono panel will only make the full 27.08 amps or thereabouts when the sun is directly overhead in the middle of summer on a fine day when the panel is relatively clean. It will also only produce max current for several hours either side of noon (I stand to be corrected :).

A rule of thumb I made up :) is that on a rainy overcast day, panels will only generate around one third or 33 percent of their max current. So instead of generating 325 watts, they may only produce 110 watts sometime around noon :).

So by putting a larger panel on the camper, you will increase the overall generation on either side of the noon day sun because the mppt controller will continue producing the max 20 amps longer with the 325 watt panel than with the 250 watt panel. With a 325 watt panel connected to a 20amp mppt controller, you loose 7a of "potential" generation at the peak of a sunny day around noon but you gain on either side of that.

I already have the 325 watt panel sitting here and would rather not go and buy a 250 watt panel. But I can. I don't normally like apply excess current to the system but I know a 20a controller will limit charge current to the battery to 20 amps.


Under different circumstances, you could buy a 200AH battery that would accept a higher charging current. I buy my batteries off auction sites and they don't usually mention max charging current.

What is the appropriate charge setting for a lead carbon gel battery? The seller said to set the controller to GEL battery.

kevin-summersby asked
klim8skeptic answered ·

2 Answers

Right size for busbar and battery cable

It is less to find for Multiplus 10000 and I ask me what is the right sizing for three Multiplus 10000 and 14 Pylontech US3000? Can I use the Victron Power-In with the 240mm² busbar? What is the right size for battery cable? 2 x 50mm²? The fusing should be 200A or 250A?

vici asked
Alexandra answered ·

1 Answer

MPPT RS Sizing limitatios

Hello ,

Im planning a setup with panels of these specs:
460 Wp
Max Isc : 14.01A
Max Voc: 41.48V

These will be connected to 48v LFP battery and MultiplusII, 3 phase.
The panels will be in an area where temperature can get to -20C in winter for few days.

The Mppt RS 450/100 seems to be the suitable for the project.
However, the specs seem overwhelming and I'm not sure how to size it correctly.

Question is: What are the limiting factors with these panels?
What is the Maximum number of panels of these specs and in what kind of configuration for ONE RS unit?

RS Pv short circuit max is 20A, and voltage cannot exceed 8x battery voltage does this mean I can only install these kind of panels in series per tracker? So a maximum of 20 panels , from my initial beginner understanding?

Also Manual for Multiplus Inverter says only 38-66 Volts max DC income, but not max Current specified in data? Does the incoming current from MPPT not matter for the inverter?


juusperunma asked
juusperunma answered ·

4 Answers

PVSyst Victron OND files

Hi all, seems there's is no such info available (OND files) to upload Victron products data base to PVSyst. It turns that there is a lot of demand on those products but is not possible to run simulations with out data.

alan-gonzalez asked
pablosol2 answered ·

1 Answer

help mppt sizing strings?

I am trying to setup an offgrid system with left over panels from moving house (long story). This would be for garden use horticulture poly tunnel, pond pumps, lights charging power tools and whatever i can use.

I have the following, and have put 5 panels on a pagoda (ready to go) with 15 deg tilt south facing with no shading. The other 5 are more of a problem as was going to put them on the garage roof but shading problems due to house shadow. Can't use main roof. Considering right of pagola but rather not due to losing growing area and would need to go higher than the 5 as cant go more down the garden or we will not have a garden.

VOC 41.62 V 665.92V TOTAL VOC
VMP 34.77 V 556.32
ISC 11.47 A 183.52
IMP 10.93 A 173.28

Q is the single mppt enough to allow for some in paralel? Trying to use mppt calc sizing but mixed results and it seems 1 mppt = all 10 have to be in series. How many can i wire in series/parallel without adding another mppt, is anything else required eg rotary isolator,
The cost of another mppt to make 2 strings of 5 one parallel and other in series @ 700ukp am wondering what to do, use less panels or bite bullet and buy mppt, do i need same one as below

Victron Easysolar II GX 3000 48v with inbuilt mppt 35a
10 x JA Solar panels spec =


garage roof - pagola in background - right side of pagola is an option but physically problematic

Andrew asked
Andrew answered ·

10 Answers


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