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solar sizing

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

MPPT sizing sanity check - is there enough headroom for cold temperatures?


a local company has just finished building an ESS system based on Victron. I'm new to the community, I have to say I really like Victron HW and SW so far. However the more I read the more I'm not sure the company designed and built the Victron system correctly. I have what looks like a standard DC-coupled ESS as Victron describes it in their docs.

I have:

  • 20x 500W panels connected in 2 strings (I think these 500W, complete data sheet can at the bottom of the page as PDF),
  • 2x MPPT (SmartSolar MPPT VE.Can 150/100 rev2).
  • 3x Multiplus II, 5000/48 (3-phase system), all loads of the house on ac-out + ac-out2

I assume they connected the panels in series of 3, since I'm seeing voltage of about 130-135V on each MPPT (I'm waiting on the company to confirm how they connected the panels). It's about 15°C outside these days. Voc of the panels is about 48V at 25°C, so I assume it's 3 panels connected serially. Not sure what they did with the remaining 2 panels after connecting 3x6=18 panels, I'm trying to find out.

I have two main questions / worries:

  1. I put the panels into Victron MPPT sizing calculator`. It says I should use the 250/85 version, because in low temperatures the voltage might go over 150V (and I believe it, I'm now at 135V with 15°C outside, in winter we easily get -20°C). Do I need to force the company to change the MPPTs? Are they crazy to not account for low temperatures when sizing the MPPTs?
  2. Is there any way the company could have connected the 20 panels in series optimally? I'm suspecting they made 6 series of 3 and then one serie with only 2 panels, so these 2 are not producing any power. This would be in line with my observations, the whole system never gives more than 8,5kW of power even with ideal conditions, but panels sum up to 10kWp.

Thanks in advance for any advice, any help would be appreciated.

Edit: links are not displayed properly.

  • panels overview:
  • panels specs:
  • MPPT sizing calculator:

jose-mite asked
jose-mite edited ·

1 Answer

Is the size of battery essential in a 3 phase EES system?

I plan to Building a 3 Phase EES System in Germany.

3 MP2 will be run on a 14.4 KWh Pylontech batterie.

15KWp PV will be fed in via the AC Out 1 that carry my whole house network including a max 4KW heatpump and a 11KW wallbox. I will use a Fronius 8.2.3 and 3.0.3 S.

1. Are the network cards essential for these to be integrated properly?

2. The main question is if I can add a 15 KWp via Victron DC chargers if I just use 14.4 KWP Pylontech for a start or what restrictions this could bring up?

3. What maximum grid load do I get. Are the 3x5000VA of the MP2 add up with the 11.2 VA of the Frinius converters?

Thanks for your feedback

borisut asked
borisut answered ·

3 Answers

Single 12v Panel capable of Charging 24v battery array MPPT 75


I have had a supplier incorrectly supply solar panels that are 12v and its impossible to return them as we remote.

Specs: 140w

Open circuit: 22.68V

Optimal operation: 18.90v

Short Circuit: 8.00A

Optimal Operation: 7.41A

Will a single panel charge 24v 24ah (2x 12v 24ah "gels" in series)

Using a Victron MPPT 75 | 15 (NO BT)


darren-1 asked
kevgermany commented ·

1 Answer

Solar panels on diferent aspects of a property - multiple mppt

hi all, just in the research stage of building a off grid solar for my home office, hoping to build a 24v system with lithium batteries, victoron inverter and 4 *320w panels. I work from home and use the office from 8am to 6pm 5 days a week, i am in the uk. The house garden faces south but unfortunately thats the house gable and not the roof. my summer house roof faces south east. I am thinking of putting 2 panel on the summer house roof and 2 panels ( for now) on a pergola that we have that is facing south, Our house is in an elevated position and gets a lot of sun. My question is this, i assume that i will need 2 seperate mppt charge controllers, one for the summer house panels and one for the house panels, these are the panel specs, current at max 9.59 amp, volt at max 33.4v, short circuit current = 10.15amp, open circuit voltage 40.9 , i am going to purchase a victron 24 volt inverter and 2 or 4 lithium 12 volt 100amp batteries, any recommendations on victron charg controllers , i assume it will be more efficient to use 2 of them , one for the pergola south facing panels and one for the south east facing panels

jeepster asked
jeepster commented ·

2 Answers

Can vertical PV panels ever reach STV voltage?

I am sizing a PV array using 405W panels, with some on a 20 degree roof and some mounted vertically on a south facing wall, to maximise winter generation.

Using a SmartSolar MPPT RS 450/100 the maximum string length allowed by the Excel Sizing Tool at 9 panels using STC data, charge limited to 100A.

This shows the max input voltage at minimum temperature as 407.2V (below max of 432V).

If I use NMOT values the sizing tool allows 10 panels with max input as 420.8V.

I plan to use 9 panels to a string on the roof.

Would it be safe to use 10 panels to a string for the vertical panels? I assume they will never reach the generation peak of the 20 degree roof panels?

The online utility does not allow over 8 panels in a string, perhaps due to the charge limiting?



Any guidance appreciated,

green-techie asked
green-techie commented ·

2 Answers

SmartSolar MPPT 450/100 Online Sizing "undersized" calculation

Apologies if I'm missing something obvious. However, using the below configuration the online sizing calculator suggests that this panel configuration is "70% (undersized)". But 8 * 405W panels, per tracker, is 6480Wp total and the datasheet gives the maximum charge power as 5.8kWp. So shouldn't this be 11% oversized?

The Excel sizing utility gives the "Total PV Power @STC" as 6480Wp and if I increase the panel wattage in the "Modules" section from 405W to 472W (just over 130%) I get the "more than 30% oversize" warning.

Any insight appreciated,

green-techie asked
green-techie commented ·

1 Answer

How can i use VE-MPPT-Calc-4_0.xlsm with libre office or open office?

I would like to use the tool VE-MPPT-Calc-4_0.xlsm.
Unfortunately I do not own Microsoft Excel but work exclusively with Libre Office.
Is there anyone who can create this toll for Libre Office?

Unfortunately, the tool does not work in the cloud onedrive Excel version.
Here the following error appears:

Excel for the web does not support running or interacting with form controls.

Thank you very much for any help.

womolupe asked
Alexandra answered ·

1 Answer

Not impressed with solar yield - Would a smaller MPPT or another panel help?

I have a Sunbeam Tough Black rated at 114W above the companionway of my sailboat. The image below shows the PV voltage & current, Battery input current and yield in watts for two normal sunny days in Norway. It's hovering around 10% of the nominal yield rather than the 50% I would have expected.


The controller is a Victron MPPT 75/15. I see that the recommendation for optimal effect is to connect 2 panels in series to that controller - but struggle to understand how much of a difference that would do?
Would a 75/10 yield more?
Data for the panel can be found here:
EDIT: Page with actual data:

sportswagoneer asked
sportswagoneer commented ·

5 Answers


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