Can I oversize 200%?? What would the implications be?

[Luk88]

This is not a valid concern. Once again, panels do not "push" current, they will only supply what is pulled from them.

Exactly. You can attemp to overload all day long and it will stay within limits (plus/minus measurement accuracy).

Most likely you'll hit the max current limit long before you get anywhere near max power. You'd have to match your string voltage exceptionally well to the inverter to get limited on power.

In fact thats what I do(connect more than rated power). I currently have 6s2p 585W bifacial panels connected to an inverter that is 6000W max on its mppt input. Thats 7kW peak. Almost 8kW if you give them extra 10% for bifaciality.

And almost all day long I max out the mppt current at 18.5A and ~245V.

 

[HarryN]

This is not a valid concern. Once again, panels do not "push" current, they will only supply what is pulled from them.

So your thinking is that:
- I can purchase a victron 100 / 30 or any other generic solar charge controller on the market
- Feed it into a large 24 volt battery pack at a low SOC
- Stay within the solar charge controller input voltage rating
- Run 3000 watts of solar panels into it.

and everything will be just fine ?

The solar charge controllers ( regardless of brand ) will just self limit the power flow?

I am less sure about this than you are.

 

[Ampster]

The solar charge controllers ( regardless of brand ) will just self limit the power flow?

You keep using the term power when the physics of electricity is about voltage and current. If the voltage is limited as you mention and and the charge controller only pulls the lesser of current to its max or the current to charge the battery, what about that math do you disagree with? Or do you disagree with the concept that the load pulls the current?

 

[Mattb4]

So your thinking is that:
- I can purchase a victron 100 / 30 or any other generic solar charge controller on the market
- Feed it into a large 24 volt battery pack at a low SOC
- Stay within the solar charge controller input voltage rating
- Run 3000 watts of solar panels into it.

and everything will be just fine ?

The solar charge controllers ( regardless of brand ) will just self limit the power flow?

I am less sure about this than you are.

Think of it this way. If your batteries are full and the SCC has stopped charging is the SCC limiting the load on the solar panels? For instance I have 4000w worth of solar panels in the midday sun that have almost no load on them since my batteries are full. My SCC's are not exploding into a ball of plasma.

 

[Ampster]

My SCC's are not exploding into a ball of plasma.

Good example. The SCC is a load that the solar panels see and that load varies based on the current it allows to flow to the batteries.

 

[Luk88]

So your thinking is that:
- I can purchase a victron 100 / 30 or any other generic solar charge controller on the market
- Feed it into a large 24 volt battery pack at a low SOC
- Stay within the solar charge controller input voltage rating
- Run 3000 watts of solar panels into it.

and everything will be just fine ?

The solar charge controllers ( regardless of brand ) will just self limit the power flow?

I am less sure about this than you are.

Exactly right. As long as you stay within the voltage limit. You can connect a megawatt sized solar farm to it and yes it will be "just fine".

Charge controllers started implementing current limits long time ago. And let me say it again.You will not hit a power limit because there is no solar panel/string that is capable of hitting these max power numbers without having too high VOC at the same time...

I have no idea why manufacturers continue to print bullshit like " maximum short circuit current (Victron), or maximum PV power (every Chinese seller). I imagine it may have something to do with the failure modes of their devices. So if a device fails catastrophically for any other reason its fuse should be able to disconnect a certain size array instead of arcing and starting a fire. However, there is enough burned charge controller pictures online to see how well it works for them (it doesn't ).

 

[zanydroid]

I have no idea why manufacturers continue to print bullshit like " maximum short circuit current (Victron), or maximum PV power (every Chinese seller).

If they are aware of a design specific catastrophic failure mode that may justify the limit, why is it BS?

 

[HarryN]

You keep using the term power when the physics of electricity is about voltage and current. If the voltage is limited as you mention and and the charge controller only pulls the lesser of current to its max or the current to charge the battery, what about that math do you disagree with? Or do you disagree with the concept that the load pulls the current?

The part that I disagree about is the concept that "all" solar charge controllers will self limit the amps going out to their rated value - and prevent their own self destruction. VS the concept that at least for some, it is the installers responsibility to make sure that the installation does not push it into heavy overload of "amps out".

 

[Ampster]

The part that I disagree about is the concept that "all" solar charge controllers will self limit the amps going out to their rated value

I agree there are probably a few that do that. However, I don't think they will last long in the marketplace. I am sure there are some that overcharge batteries too.

 

[Mattb4]

The part that I disagree about is the concept that "all" solar charge controllers will self limit the amps going out to their rated value - and prevent their own self destruction. VS the concept that at least for some, it is the installers responsibility to make sure that the installation does not push it into heavy overload of "amps out".

An installer can only go by the ratings. If a 10 amp rated charger instead charges at 20 amps the fault is the manufacturer. Just like if a charger outputs the wrong voltages. There may be a duty cycle limitation that an installer should allow for.

 

[HarryN]

There is a fairly long thread about it here. I guess I need to read it again. I didn't come to the same conclusion but could be wrong.

Victron MPPT over panelling

By how much can you over panel a Victron 100/20 the data sheet just says the MPPT will deal with it !!! a) If more PV power is connected, the controller will limit input power.1b) The PV voltage must exceed Vbat + 5 V for the controller to start. Thereafter the minimum PV voltage is Vbat + 1...

diysolarforum.com