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Hot weather seems to have reduced PV production

Since a week or two ago we have had sunny weather every day here in western france. It's not that hot, 20 - 25C but I have noticed a 1kw drop in max production (from 4.4kw nominal power installation).

Is this normal due to higher panel temperatures or should I be looking for a problem somewhere?

usernamepasswordbs asked
seb71 edited ·

16 Answers

Two MPPT, one generating little charging

I have two pairs of solar panels each with own smart solar MPPT.

First pair are 2x 120W panels with 100/20 controller generated over 1Kw yesterday. Happy with this.


Second pair are 2x 80w panels with 75/15 controller only generated 30w. Something is wrong. When first installed these could generate 700w in a day. The panel voltage/current seems ok but it's just not getting pushed into my batteries.



Images show history from yesterday when I was not using shore power and current status of the suspect set of panels. I read this as 29W network but only 3W charging. Is that correct?

Any thoughts on what could be going wrong?

ningaloo asked
ningaloo commented ·

2 Answers

Why would 2 x 24V panels in series read 80+V PV?

Hi everyone. I have Victron solar panels; each is 24V rated 200W, they have 72 cells instead of the normal 60, and I have four pairs of them. Each pair is in series to give 48V nominal and each pair has its own MPPT. When I read PV from the MPPTs the starboard side shows 60V on one pair and 65V on the other. This is a little high I think but the port side reads over 80V on both, which is concerning. Does anyone know why this might be happening and how concerned I should be?? Thanks in advance.

eyacht asked
groningen edited ·

5 Answers

BMV-702: How do I connect 2 parallel AGM batteries?

Hello everyone!

I need some help installing a BMV-702 on my sailboat. I am sailing solo and it's important for me to know about the capacities of the batteries while I'm on the ocean.

My question: Can I connect both negative cables coming from the batteries to the battery side of the shunt and connect the loads side of the shunt to the bus bar?

Here are some more details about my setup:

Battery Setup

I have two 12v 100Ah AGM batteries installed.

The previous owner had built a box where the two batteries can be connected or disconnected to the system individually or both at the same time (see pictures below).

I would always use battery 1+2 together and frankly I don't understand why there is the option to pick between the batteries individually. From what I understood it's unhealthy for the batteries if they're used in parallel mode and don't have the same voltage.

Solar Setup

I'm using two solar panels and a MPPT 100 | 20 solar charger.

Wiring (+ Side)

I added two images, one form the outside and one from the inside of the box, where you can see how the positive side coming from the batteries and solar charger are wired up.



The positive cable leaving the battery selection knob, goes directly to a 30A fuse before it is connected to the different consumers.


Wiring (- Side)

The negative cables of the batteries are directly attached to a bus bar, see picture below.


Thank you in advance!!

Best regards,


cedric-vincent asked
JohnC answered ·

1 Answer

Mixing PV advice.

Hi All

I’m looking for some advice. I’ve got the follow spare panels: 3x380watt - JAM60S20S380MR and 1x450watt - JAM72S20460MR.

Is there anyway I can combine them on 1 string efficiently and what MPPT would you recommend?

h2009 asked
JohnC answered ·

2 Answers

Solar panel not pulling in sunshine

I’ve had this set up for a couple of years now, bought with a campervan. No problems at all.

Last week I gently wiped the solar panel with a sponge to clean it.

Now the panel is only showing 1-2w in direct sunshine !?

I gave it another wipe this morning with a clean damp cloth - no improvement at all. Haven’t knocked, bumped, or pulled any wiring.

What could be wrong? Can anybody give layman’s (ie a simpleton!) directions or suggestions on what to try, check or do?


Image Caption



sputnikspud asked
mvas commented ·

3 Answers

Staging upgrades - temporary imbalances


330W panel, 40A MPPT, 2.4kWh 24V LFP battery, Multiplus 24/800.

Loads: Single "office" circuit running 100-200W of monitors, pcs, the usual junk.

Configured with the virtual switch on the multiplus to ignore AC and favour battery, It behaves much like it should, like a "house battery". On good days it stays off-grid overnight. On bad days it switches back to grid in the evenings.


990W panel, 40A+15A+15A MPPT per panel, 8kWh battery. Possibly a bigger or second multi.


I can't afford to do that all at once. Not without breaking the rules of no "non interest free" credit.

I want to start with the other 2 panels. The power output of which would be 0.4C on the batteries if the loads are off at peak sun. It might have to run that way for 3 months of summer before I can finance and source the batteries.

I intend to run all 3 panels on an MPPT controller individually. The panel site has progressive shading from both ends.

I am currently (pun?) looking at the Victron 100/15 MPPT units. I can "cap" the panel output to 26A or so by putting 2 of the new panels temporarily into a single 100/15.

Or... if they support current limiting I could probably balance the panels and battery far more nicely, so that i get the advantage of all 3 panels during lower light, but the current gets capped in "direct sun" to not hammer the battery.

I have seen other posts going into dynamic control and DVCC so that the inverter loads and battery net current can be taken into account and allow the inverter to make use of the full 990W while the battery charge is limited by the VE MPPTs.

3 months might be long enough to work without that. Not unless it's easy to inject via MQTT or similar interface under my control system.

3 months is too long to work with something like a temporary 250W heater load on the inverter to bleed panel power.

Options suggestions?

Additionally.... increasing inverter power from 800VA to maybe 2kVA... is the easiest option paralleling two multiplus's? Can a multi work in tandem with a more basic pheonix? Is chaining/tie-ing inverters together "dark siding" or is it supported yet?

paul-campbell asked

0 Answers

24v solar panels to 12v battery


I have 1200w 24v solar panels to charge 12v batteries. What mppt solar charge controller i need in between?

samaya asked
samaya commented ·

1 Answer

MPPT Performance

I have a;

6 panel 420w array at 85v that feeds into a 150/45 victron mppt and a

4 panel 330w array at 70v that feeds into a 100/20 victron mppt.

The array size difference its about 63% so in my head I would expect that to be the difference in watt output between the two (both have the same orientation outside).

But the actual watt difference is quite large, the larger array actually outputs about 120% as much power as the smaller array.

My question is, are the smaller capacity mppt's less efficient at managing the array even though the numbers are within tolerances? Am I likely to get closer to my expected outputs if I used say a 150/35 on the smaller array? Or is the difference purely down to the panel efficiency?


you can see the huge difference above

Tobias Franklin asked
Tobias Franklin commented ·

1 Answer

combining MPPT 100/30 & 75/15 same panel and separate batteries and loads


I have a 400 watt panel that I would like to use to charge a 24 V battery bank and a 12 V battery bank.

Is it possible for MPPT100/30 and 75/15 share the same panel and charge two separate battery banks?

one sub answer address a similar question;the answer from user 'wild-thing'. Seems like there is a competition,with 12V get fully charged or need to be charged before MPPT 75/15 turns-on.Since in my case the batteries are simultaneously used and hence it may not be practical.

Is there any other way to do this without the controllers competing with each other?

A dc-dc isolated charger may be another option but has efficiency issues ~87% compared to an MPPT charger

vicsla asked
vicsla answered ·

2 Answers

Two solar panels: one MPPT or two MPPTs?

I have two different solar panels on my van: the first is 90 W @ 18V and the second is 165 W @ 17.84V.

Here is the schematic:


I've put the panels in parallel with two (electronic) diodes, connected with one Smart Solar MPPT 100V | 30.

In this scenario, the performance of a single MPPT with the two panels in parallel are better or worse than two MPPTs in parallel, one MPPT for every panel?

Thank you

Riccardo Sala asked
mvas edited ·

2 Answers

Solar Panel 4a vs 4b


I’m rather new to this and have been researching the Victron solar panels and notice that they do 2 versions of the 115W Mono. Series 4a & 4b.

The spec values appear to be the same, and the only difference I can see is that the 4b is 15mm longer, but surely that can’t be the only difference, as logic tells me that 4b is a newer model.

can anyone shed any light on this for me please.

Many thanks

the-batman asked

0 Answers

Why PV only produces during high loads?

I have a 2600w solar array all on separate 100/50 MPPT's. On average it's producing around 800w even if my batteries are from 60-90%. But if i turn on a high load it jumps to 1500w. My question is why doesn't it charge at 1500w even when my battery are at 60%?

maxtosea asked
maxtosea edited ·

5 Answers

How to correctly configure solar system?

Hi! Can anyone help me to configurate correctly my solar system?

I have Multiplus 48/1600/20, MPPT 100/20, LiFePo4 battery without bms and two solar panels 450W each. ESS with Optimized mode (With BatteryLife) and without feed-in. But sometimes on VRM I see that small amount of energy goes into the grid. The main idea is to make system work like this:

When solar power isn't enough to cover the load - battery will discharge till specified voltage or SOC.

When solar power is enough - extra power will charge the battery.

System can take the energy from grid only when battery rich the minimal SOC or there is no solar power.

I need to survive without the export from grid as much as possible.

Is it possible to configure system like this and should anyone help me with this?

chebanov asked
Alexandra answered ·

1 Answer

SmartSolar 100/30 2x 200W 36 Volt panels in serial or parallel

I have installed the smartsolar 100/30 and installed 2x 200 Watt 36 Volt panels in serial.

WIth the test I see on one panel connected. a voltage off 47,47 volt and in parallel dubbel so around 95 Volt. I charge 2x 100 A/h AGM in parallel.

Question is now is this the best solution.because of the high voltage, and should I move to 2x parallel configuration? Picture attached from the panel and screenshot during testing with 1 panel connected.

Thanks for your idea's about this,



jollyhobby asked
jetlag answered ·

2 Answers


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