MPPT in high temperatures

Jakachira

I have read that MPPT works pretty well in cool temperatures.

What about in high temperatures? How does it perform?

Cariboocoot

Re: MPPT in high temperatures

Jakachira wrote: »

I have read that MPPT works pretty well in cool temperatures.

What about in high temperatures? How does it perform?

MPPT works the same, regardless of temperature. It's the panels that lose output as they heat up. The controller makes "best use" of whatever they produce.

niel

Re: MPPT in high temperatures

you will find that it is better that a controller and any electronics will last longer when not subjected to high heat as heat is the enemy of any electronics, but this is more to do for the longevity of the product rather than an output point of view. coot probably said it that you confused the controllers with the pvs as pvs will slightly degrade their outputs in heat.

Jakachira

Re: MPPT in high temperatures

Thanks guys for the messages

Another question is it possible to run a 12V Panel and a 24V panel in parallel through an MPPT, charging a 12V Battery?

Will 24V Panel give more than what is rated to the 12V Battery throught the MPPT?

Saying 100W@12V and 120W@24V, will the MPPT give 100W@12V and 240W@12V to the 12V BATTERY if i joint the two panels in parallel

Cariboocoot

Re: MPPT in high temperatures

Jakachira wrote: »

Thanks guys for the messages

Another question is it possible to run a 12V Panel and a 24V panel in parallel through an MPPT, charging a 12V Battery?

Will 24V Panel give more than what is rated to the 12V Battery throught the MPPT?

Saying 100W@12V and 120W@24V, will the MPPT give 100W@12V and 240W@12V to the 12V BATTERY if i joint the two panels in parallel

The answers are no, and no.

First off, the Wattage rating of a panel is a "total power" figure. Basically, the 120 Watt 24 V panel would produce 120 Watts on either a 12 Volt or 24 Volt system. The current it produces would be different: 120 Watts @ 12 Volts = 10 Amps, 120 Watts @ 24 Volts = 5 Amps. This would be a difference in charge rate, but does not affect the over-all power.

Second, paralleling panels with such vastly different Vmp (Voltage at Maximum Power) is bad idea. The 12 Volt panel would essentially contribute nothing, and could be damaged by the output from the 24 Volt panel.

Now I'm thinking a basic primer on PV function might be a good addition to the FAQ's, because this is one of the things that is very confusing to people.

BB.

Re: MPPT in high temperatures

With all of the different panel and PWM/MPPT charge controller options out there, plus the fact that people can configure different charger to the same battery bank--the questions get confusing fast...

The simple answer is that for an MPPT charge controller, adding parallel strings need to have the same Vmp (i.e., if one string is 35 volts Vmp, then the rest of the added parallel strings should be around 35 volts DC-- roughly +10% bminus 10% of each other--for example 31.5 volt to 35 volts range OR 35 volts to 38.5 volt range). The farther the way from that 10% range a panel string is, the more likely that the MPPT charge controller will harvest less than the "total available power"... More or less like paralleling a 12 volt + 24 volt battery together (with blocking diodes). You get the current from both batteries at 12 volts but only the 12 volt power. Or at 24 volts, you only get the current/power of a single battery at 24 volts.

MPPT charge controllers are not designed or tested to figure out how to get the maximum power from widely differing Vmp voltages on one MPPT input--plus it is physically impossible to get "maximum power" from a 12 volt and 24 volt panel paralleled together.

If you have a bunch of different panels--you can put two or more MPPT controllers in parallel on one battery bank. Each MPPT controller connecting to its own Vmp Array (12 volt, 24 volt, etc.). Remember that MPPT (or PWM controllers) cannot up convert voltage (a 12 volt panel cannot charge a 24 volt battery bank).

Also, when putting panels in series (to increase voltage)--the current should be withing 10% of each other for optimum performance. The farther away the panels are from Imp matching, the more power is lost (like placing a 1.5 volt D Cell flashlight battery in series with a 12 volt car battery--you will get 13.5 volts, but be limited to the current supplied by the much smaller flashlight cell).

-Bill

Jakachira

Re: MPPT in high temperatures

Thank you, guys for the infomation.

blackswan555

Re: MPPT in high temperatures

I have read that MPPT works pretty well in cool temperatures.

What about in high temperatures? How does it perform?

Like most electronics their efficiency fall`s off with temp, EG the earlier Charge controllers were "spec`d" at 25c and it is recommended to de-rate by 1 amp per deg C above, The later 40c so a lot nearer to where most actually work (MX vs FM) Depending on manufacturer, be careful on how the "spec`s" are written and how you read them.

have a good one
Tim

PS, no diss to OB, They are one of the better companies at listing true (real world working) spec,