Solar Panels/battery banks/inverter

[coopec]

After blowing up a MPPT Controller I read the installation instructions and successfully installed a replacement. I now have:

On/off switches on the solar panel leads.​

A 1/2/Both switch on the positive cable from the controller so I can direct the charge to either battery banks. (that works fine)​

I am about to wire up the 3000W/6000W inverter and will use 00 B&S (AWG) as the leads will only have to be (max) 2ft long.​

Now a couple of queries:

In working out the size of the cables to the inverter is it normal to ignore the "surge" current?​

I wired up the MPPT Controller- P/N from the solar panels, P/N to the batteries, P/N to a light (or bilge pump or fan) What is that for? And why is the light on 24 hours a day? I thought it would only be on when the sun was shining I don't think I've botched up the wiring.​

Instead of wiring up a light (or bilge pump or fan) could I wire up the bilge blower. (I'd have to check the amperage of that but it would be higher than (say) a light)​

​

Advice will be appreciated​

 

[vas]

would be helpful if you could mention brand/model of MPPT.
Some of them have 3sets of +- terminals, third being called load so in theory you connect some load directly there (for some reason that escapes me tbh) IMHO, you DONT HAVE to connect something there!
interested to hear how you blew up an MPPT controller.

V.

 

[edsailing]

From your description, it looks like the light is also fed from the batteries.....

 

[coopec]

would be helpful if you could mention brand/model of MPPT.
Some of them have 3sets of +- terminals, third being called load so in theory you connect some load directly there (for some reason that escapes me tbh) IMHO, you DONT HAVE to connect something there!
interested to hear how you blew up an MPPT controller.

V.

This is the model










When I tried to install it the battery was not connected nor was the light globe and I attached the positive lead from the panels (there was a loud phutt!)


Installation instructions (Relevant part only)
9. According to the battery voltage grade, the controller can automatically set charge-off voltage. When the battery voltage is 12 volts or 24 volts, it will automatically set the charging voltage parameters.

The prerequisite is that the 12-volt battery is charged with an 18-volt solar panel, and the 24-volt battery is charged with a 36-volt solar panel.
The battery must be connected first and then the solar panel.

 

[Rappey]

Usually if a light is on its showing the system is working. Some change colour or flash depending what part of a charging cycle they are in.
The extra output with light bulb pic is often only 2amp max. Never seen a use for it myself.
I managed to kill a pwr controler by plugging in a lan display for a mppt controler ☹
As mentioned, you don't need to connect the "load"
Those type of controllers are normally pwr wrongly labelled as mppt and at that price it's unlikely to be mppt.

 

[PaulRainbow]

After blowing up a MPPT Controller I read the installation instructions and successfully installed a replacement. I now have:

On/off switches on the solar panel leads.​

A 1/2/Both switch on the positive cable from the controller so I can direct the charge to either battery banks. (that works fine)​

I am about to wire up the 3000W/6000W inverter and will use 00 B&S (AWG) as the leads will only have to be (max) 2ft long.​

00AWG is 67mm sq, not close to being big enough. Should be a minimum of 95mm sq

Now a couple of queries:

In working out the size of the cables to the inverter is it normal to ignore the "surge" current?​

I wired up the MPPT Controller- P/N from the solar panels, P/N to the batteries, P/N to a light (or bilge pump or fan) What is that for? And why is the light on 24 hours a day? I thought it would only be on when the sun was shining I don't think I've botched up the wiring.​

Instead of wiring up a light (or bilge pump or fan) could I wire up the bilge blower. (I'd have to check the amperage of that but it would be higher than (say) a light)​

​

Advice will be appreciated​

Impossible to answer without knowing the make/model of controller. In any case, i'd ignore the load terminals and just connect toe panels and batteries, wire everything else up as normal.

 

[PaulRainbow]

Usually if a light is on its showing the system is working. Some change colour or flash depending what part of a charging cycle they are in.
The extra output with light bulb pic is often only 2amp max. Never seen a use for it myself.
I managed to kill a pwr controler by plugging in a lan display for a mppt controler ☹
As mentioned, you don't need to connect the "load"
Those type of controllers are normally pwr wrongly labelled as mppt and at that price it's unlikely to be mppt.

I agree, very unlikely.

 

[vas]

..and depending of course on size and voltage of panels and batteries, fairly inefficient. Cheap nevertheless though

 

[coopec]

00AWG is 67mm sq, not close to being big enough. Should be a minimum of 95mm sq



Impossible to answer without knowing the make/model of controller. In any case, i'd ignore the load terminals and just connect toe panels and batteries, wire everything else up as normal.

Sorry! I should have mentioned it is a 24V system (not 12V)
(Looking at the chart 00AWG should be fine)

 

[PaulRainbow]

Sorry! I should have mentioned it is a 24V system (not 12V)
(Looking at the chart 00AWG should be fine)

Yes, fine for 24V

 

[Rappey]

, fairly inefficient.

They are very cheap, as little as £12 compared to nearly £70 for mppt but wouldn't say they are that inefficient as if you were getting 6a from a pwm you get maybe an amp more from mppt in parallel.
The cheap pwm type do seem reliable

 

[coopec]

They are very cheap, as little as £12 compared to nearly £70 for mppt but wouldn't say they are that inefficient as if you were getting 6a from a pwm you get maybe an amp more from mppt in parallel.
The cheap pwm type do seem reliable

I looked at the box and it is made in China. They seemed to be selling well on eBay but from Australian sellers. I am sure the ACCC would be right on to the Australian resellers if it wasn't a genuine MPPT controller (Misleading conduct). The fine for "misleading conduct" can be huge so I feel quite confident it is an MPPT controller

Incidentally somehow we can't buy from China (or Asia) on eBay anymore. I think it may be because Chinese Government subsidizes postage. Governments in emerging nations are allowed to subsidize postage and China maintains it is still an emerging nation. It may have been a deliberate policy of Australia Post to take a month or so to get a package from (say) Sydney to Perth as retaliation.

18 Oct 2018 — Trump Is Right About China's Postal Subsidy ... in the same category as Bosnia, Botswana, Cuba and other developing countries.

 

[vas]

there are many long discussions on the web on various exceptionally cheap solar charge controllers mentioning MTTP.
the concensus is they are not. Not sure if ACCC can be bothered, or is informed on that. Further, since they are functional devices doing what they are meant to, calling them MTTP instead of something else is I guess trivial.

 

[Rappey]

I am sure the ACCC would be right on to the Australian resellers if it wasn't a genuine MPPT controller

Ebay is full of cheap chinese stuff making all sorts of fake claims. Mppt are much more expensive than pwm type yet yours is cheaper than many other chinese pwm type..
Look up chinese climbing gear on ebay , it's all ce marked and carries cert numbers to say it's all been tested etc, yet all of it is fake. There is only one chinese brand that is legit.
I know this as looked them up !
I could be wrong but led to believe that ,simply put, Mppt convert all the input voltage to amps. Pwm if 12v cut off voltage above that ,hence the lower output.
I wouldn't stress about it though as bang for buck they are very good value for money.

 

[pvb]

I looked at the box and it is made in China. They seemed to be selling well on eBay but from Australian sellers. I am sure the ACCC would be right on to the Australian resellers if it wasn't a genuine MPPT controller (Misleading conduct). The fine for "misleading conduct" can be huge so I feel quite confident it is an MPPT controller

It's not an MPPT controller. There are lots of YouTube mentions of these cheap PWM units being sold as "MPPT" controllers.

 

[coopec]

It's not an MPPT controller. There are lots of YouTube mentions of these cheap PWM units being sold as "MPPT" controllers.

Thanks PVB. I'll look into that.
I've become very wary of buying anything from China ,(especially batteries and SD cards)

Here we go:
why does ebay allow fake MPPT solar regulators to be sold on Ebay Australia

 

[coopec]

Ebay is full of cheap chinese stuff making all sorts of fake claims. Mppt are much more expensive than pwm type yet yours is cheaper than many other chinese pwm type..
Look up chinese climbing gear on ebay , it's all ce marked and carries cert numbers to say it's all been tested etc, yet all of it is fake. There is only one chinese brand that is legit.
I know this as looked them up !
I could be wrong but led to believe that ,simply put, Mppt convert all the input voltage to amps. Pwm if 12v cut off voltage above that ,hence the lower output.
I wouldn't stress about it though as bang for buck they are very good value for money.

Thanks for that Rappey.
I won't stress about it but I will keep it in mind for the future- when I've got time to do something about it. It appears to be working

But it is just another reason I won't buy anything "technical" (like SD card, batteries, safety gear etc ) from China. It doesn't say much for eBay and I'll keep it in mind for when they ask me to do their next survey.

I just responded to a post by PVB quoting this link. why does ebay allow fake MPPT solar regulators to be sold on Ebay Australia

 

[Rappey]

After reading your links it's not as such a rip off as the price you are paying for a pwm is not expensive and these units seem very reliable but wrongly advertised.
Not everything cheap from China is rubbish.
Clone lithium batteries are a lot cheaper and on the whole seem quite good.
Some of their electronics are really good.

 

[coopec]

If I have to get a proper MPPT Controller what would be a decent brand at a realistic price?
My panels are Renogy so maybe I'll stick with Renogy A 30A Renogy Controller costs $150 (I hope I don't blow that up)

(I'd prefer not to buy Chinese)

 

[Bru]

That unit looks oddly familiar. As an strangely like at least a dozen different brands of "MPPT" solar controller all of which are functionally identical and have the self same PWM controller circuit inside the case. And the PWM controller circuit in question is astonishingly similar to a Marlec Spectra PWM controller. So astonishingly similar that it's obviously been reverse engineered

So I don't need the instructions for the knock off unit to advise that the "Load" output is actually potentially quite useful. The load output can be used to supply loads (up to it's rated capacity) that the controller will disconnect if the battery discharges below a certain point (or to be more precise, if the battery voltage drops to the cut-off point). This could, for example, be used to prevent (say) a cool box from flattening the battery or similar

The load output is probably less useful in a boat than it would be in something like a campervan or caravan and can safely be left disconnected

The battery should always be connected first to these controllers as the controller senses the battery (bank) voltage and configures itself accordingly. Connecting the panels first won't (normally) kill a Marlec controller, I guess the Chinese left out the protection circuitry to save money