Connecting more Solarpanels than an All-in-One System is rated for

[Wohl]

Does anyone know what would happen if i connect more solar panels to an All-in-One System than the system can handle specs-wise? No worries this is nothing but a thought, i am not trying to ruin any good system! I guess it would be more dangerous in an All-in-One System because i couldn't just replace the charge controller ifthe charge controller would break.

I keep thinking that solar charge controllers are rated for solar panels assuming they are in full sunshine?. In a 12v system: when a charge controller is rated for 50A, that means i can safely connect 600W of solar Panels. But unless the sun is shining, i don't think i am anywhere near the maximum of 50A the controller could handle.

If i knew the weather would be cloudy most of the year, wouldn't it be possible (or even wise) to connect maybe 100W or 200W of solarpanels more so that i can reach a higher amperage when the weather isn't perfect? I bet mechanisms could be found to prevent the max amperage to go above 50A and components to be damaged.

I keep wondering if there is a way to incorporate the cloudy weather into my thought processes. Seems smarter to calculate for the weather i actually have and not for the weather i would like to have

 

[svetz]

Over-powering your system voids any warranty which you'd need as it could fry it. But you're right that panels don't generate their full wattage in a variety of conditions; see this post as it explains it and has a graph so you can see how energy varies. See this thread on current limiters as if you can do that, it would automatically regulate the power.

 

[grizzzman]

You need to contact the manufacturer. Some mppt controllers and a few PWM controllers can deal with over paneling. As an example I have a Bogart engineering SC2030 coupled to a TM2030 this is rated at 31 amps 520 watts. My system clips power at 31 amps(I have 620 watts of panels). Your more likely to find an MPPT that can do this. Good luck!

 

[Wohl]

Oh wow i'm glad to see the idea is already out there. Learned a new expression: Overpaneling. Sounds cool, maybe the developers of these All-in-One Systems include this as a feature in future products; unless it is easier to just improve the scc to handle more amps. I'd love the idea of these All-in-One System being able to run on few panels as well as on many panels. That way somebody getting into solar could slowly scale their system, starting out with only few panels. I imagine it to be wonderful being able to add more and more panels as i understand my own electricity habits while i start to actually depend on solar for all my electricity. I'd hate to start Vanlife and completely overestimate or underestimate my power needs.

 

[grizzzman]

Overpaneling for me is not the sun-filled days. It's for the bad (rainy-cloudy) days. How many times have you herd"I have too much solar!" Build it big will help the do-over blues.

 

[b.james]

Right atm I have two 265 watt panels (530watts possible) feeding a Victron 100|15 charge controller . The charger is rated then at 415watts and anything over is clipped.

It sits all day at 415 watts on sunny days but its only weeks old yet and it gets quite hot so my plan is to replace it quickly with a bigger charger inverter unit for $1100AUD as the next bigger Victron is $400AUD and not worth the money.They just skyrocket from there.

As Victron advertise that this is what happens they could not void the warranty if you were silly enough to tell them that on needing repair.
I don't like Victron . Too expensive, but there are others that do the same.

 

[gnubie]

Swings and roundabouts. Victron might be comparatively expensive but it is stuff you can put in and forget about. It'll reliably do what it said on the box, unattended, for years.

If the charge controller is mounted with the correct spacing behind the heatsink and ambient temperature is within the stated limits the controller might well get warm, mine certainly does, but not burn your hand hot. Convection cooling will keep it within spec. If the temperature of the unit ever goes high it will thermally limit to ensure it doesn't die from overheating.

Consider this: Not too long ago, in a rare departure from normal events, Victron released a firmware version that in limited cases killed a particular model controller. What did they do about it, aside from fixing the problem of course and letting everyone know about it via their web site articles?

Replaced any controller that was killed by the issue.

That's pretty good in my books.

 

[Dave1]

I asked this question about the MPP Solar units because their 500W max input on the 12V PIP LV is one of their biggest limitations. I was told that if the input goes over 500W the unit will shut down. This limits the ability to put 6 pannels in a 2P3S arrangement which is good for limiting wire size and efficient.

I'm tempted to do it anyway and see what happens. Most of the time six 100 watt panels aren't going to output over 500W anyway. I suppose I could always tape over a few squares on each panel if it becomes a problem to limit their output. I just want to maximize output as much as possible during the lower light angle times of the day.

 

[b.james]

Most of them will just limit the input to what they want by passing the excess to resistors and burnt off as heat. "burnt" being the operative word ,if you have too much input for too long a time then something will give . What happens then depends on how its designed . I'm talking 50 volts over for hours a day for months on end here.
Throw a bit of timber over one string on a panel will reduce it or over one small panel in one string wil remove that whole strings input usually on modern panels.

gnubie Any electronic device that gets hot suffers . Its always best to keep it as cool as possible and as close to ambient as possible but TV's etc with a heating element are just meant to reduce the greater expanse from cold to running warm . That's why taxis get 1 million kilometers at times , they never get cold.

 

[gnubie]

I asked this question about the MPP Solar units because their 500W max input on the 12V PIP LV is one of their biggest limitations. I was told that if the input goes over 500W the unit will shut down. This limits the ability to put 6 pannels in a 2P3S arrangement which is good for limiting wire size and efficient.

Really comes down to how well they did their job designing it. Their device can can already tolerate the VoC from the solar array so if the array can supply more amps then the charger draws the solar input voltage will go up. No biggie there. No smoke. No fire, no need to shutdown. Nada.

The problem is does it have any current limiting to protect itself? Does it just try to push as much as the load on it output will take. That can quickly lead to the destruction of their switching transistors. Similarly when doing MPPT searches if it hits the maximum current rating does it stop there or does it keep drawing more and more current, as much as the load in the output will absorb, in an effort to locate the MPP and again transistors fail and smoke comes out. If you are lucky there is thermal limiting but that is usually not fast enough to stop the inevitable.

Dumping excess to a resistor is improbable and pointless. If you are going to put transistors in the device to handle that can handle the full current to the point of being able to dump the excess into a resistor array, you can already handle the full current as it is. Current limit the output and done. Where exactly do you put 50+ watts of dump resistors into a charge controller these days in such a way that it wont set the controller on fire? 50, 100, 200 watts is a hell of a lot of heat to get rid of. I remember linear charge controllers. If you want hot, check out the regulation transistors on those things.

It'll be interesting to see what does happen. If it's worth its salt, it will just current limit and keep on truckin'.

 

[gnubie]

gnubie Any electronic device that gets hot suffers . Its always best to keep it as cool as possible and as close to ambient as possible but TV's etc with a heating element are just meant to reduce the greater expanse from cold to running warm . That's why taxis get 1 million kilometers at times , they never get cold.

Leaving the heaters on in the picture tube was done for one reason and one alone, lowering the time between person pushing the on button and the picture appearing.

 

[Dave1]

It'll be interesting to see what does happen. If it's worth its salt, it will just current limit and keep on truckin'.

Well after all that talk of things smoking I'm not sure I want to find out. ?

 

[Dave1]

I emailed MPP Solar about this. They asked about which solar panels I am using and since I hadn't bought any yet I told them I would be using 6 HQST 100W panels in 2P3S arrangement. and provided specs.

Here is the response I got.

-------------------------------------------------

HI David
Noted,
After checking with RD. you can still use 3 in series , 2 in parallel 600w panel with 812LV-MS. It will be the max the built in mppt charger can take.
So it’s good. To order. please let us know.

Please note there are currently several Mainland Chinese companies who have copied our inverters and offering them at lower prices. For your own benefit, please do NOT support these inferior products. MPP Solar operates independently and is NOT affiliated to these companies in any way.

Kind Regard
Peggy Hung
Sales Department
peggy@mppsolar.com
TEL: 886 2 8797 8896 ex 603


www.mppsolar.com

From: David W
Sent: Wednesday, October 16, 2019 9:28 PM
To: peggy@mppsolar.com
Subject: Re: 812LV-MS Over paneling

I have not ordered them yet. But I was thinking of connecting 6 of these panels in a 2P3S arrangement. under normal conditions, they will stay under 500W but I live in a sunny location at a high altitude so they could go over during the sunniest part of the day.

Specification
Max Power at STC: 100W
Open Circuit Voltage: 21.7V
Short Circuit Current: 5.84A
Opitmum Operating Voltage: 18.2V
Optimum Operating Current: 5.58A
Operating Temperature: -40℃ to 90℃
Dimensions: 904x657x30mm / 35.6x25.9x1.2 in
Weight: 6.5kg / 14.3 lbs

Thank you,
Dav

 

[gnubie]

Please note there are currently several Mainland Chinese companies who have copied our inverters and offering them at lower prices. For your own benefit, please do NOT support these inferior products. MPP Solar operates independently and is NOT affiliated to these companies in any way.

I guess that's to be expected. I wonder how we can tell if a unit is a knock off or not. I wonder if they can give any advice on what to look for as often the knock offs do cut corners and that can be used to tell the difference. Even the cheapy MakeSkyBlue controllers were ripped off. MakeSkyBlue did post a how-to-spot-the-fakes guide on their site.