Question about how to interpret our Charge Controller numbers

Rocketman

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One item that could really help you is a battery monitor. Lookup on the internet- Victron BMV712. (There are other ones as well). The battery monitor (once it’s setup correctly) can tell you how full or empty your batteries are, how much power you are using/making.

Also while looking read up about the Victron smart solar mppt 100/30.

This way you will know the “type” of gear that is best - so you can compare what is available locally.
 

sunshine_eggo

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Sorry,. But tttt

I will find that information, but does it make any different that we have two batteries, each 105 A ?

It's on the label on the back of the panel.

Are the batteries in parallel for 12V or in series for 24V. Based on your numbers in your first post, they're 12V.

If you want to series your batteries for 24V and replace your inverter, then you could likely use your 330W panel with somewhat improved power.
 

Cheesemaker

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It's on the label on the back of the panel.

Are the batteries in parallel for 12V or in series for 24V. Based on your numbers in your first post, they're 12V.

If you want to series your batteries for 24V and replace your inverter, then you could likely use your 330W panel with somewhat improved power.


Thanks, It's not so easy for me to get on the roof to look behind the panel so I have messaged the man who installed it.

He says he has an MTTP controller, this one, for $120. I know it's not top of the range, but as long as it works and makes our panel more efficient, we'd be happy.
 

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Cheesemaker

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It's on the label on the back of the panel.

Are the batteries in parallel for 12V or in series for 24V. Based on your numbers in your first post, they're 12V.

If you want to series your batteries for 24V and replace your inverter, then you could likely use your 330W panel with somewhat improved power.


Thanks, please can you check the specs on the photo I posted of the MTTP charge controller? It says "maximum charging current 20 Amps" - That means it's too small for us , no ? We need 30 amps , don't we?
 

Cheesemaker

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It's on the label on the back of the panel.

Are the batteries in parallel for 12V or in series for 24V. Based on your numbers in your first post, they're 12V.

If you want to series your batteries for 24V and replace your inverter, then you could likely use your 330W panel with somewhat improved power.


Our batteries are in parallel for 12. V

If we installed an MTTP charge controller, which allowed the full 330 W of panel power to come through, would our 12 V 2000 W inverter be able to manage that?
 

Cheesemaker

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I'm now
One item that could really help you is a battery monitor. Lookup on the internet- Victron BMV712. (There are other ones as well). The battery monitor (once it’s setup correctly) can tell you how full or empty your batteries are, how much power you are using/making.

Also while looking read up about the Victron smart solar mppt 100/30.

This way you will know the “type” of gear that is best - so you can compare what is available locally.
Right now we can't afford the Victron. I know, we're on the Chinese bargain basement ride. :cool:
 

sunshine_eggo

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20A * 13V = 260W, so it's definitely an improvement, but still a little small. Note that you'll only get 330W at high noon, so you'd probably only be losing anything in the middle 3-4 hours of the day. In any case, you're going to get 260W vs. the 110W.

If it's your only choice, great. If he can get that same brand, or RichSolar or Renogy in a 30A, better.

Inverter won't care.
 

Rocketman

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that SCC can handle 260 watts - your panel is 330w. What usually happens ( you need to verify before purchasing), is the power will be clipped above 260w. The good thing is you will get more power - especially compared to now, but you may want to wait and see if you can find a mppt 30a.
 

sunshine_eggo

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I would get the panel info before I purchase the MPPT.

If you have a receipt or documentation on the panel brand and model, can get the info online.
 

Cheesemaker

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I would get the panel info before I purchase the MPPT.

If you have a receipt or documentation on the panel brand and model, can get the info online.


Thanks, he is sending me the tech manual for the panel tonight.

Does it
go against us that we have a 12.V parallel setup with two batteries? Is 24 V. series connection always better? do we lose out by having 12 V ?
 

Cheesemaker

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that SCC can handle 260 watts - your panel is 330w. What usually happens ( you need to verify before purchasing), is the power will be clipped above 260w. The good thing is you will get more power - especially compared to now, but you may want to wait and see if you can find a mppt 30a.

Thanks, he has a 30a. for $150, waiting for him to send brand name and photo.

If our panel is compatible (he says it is), will we be able to add more panels and batteries later if we want?
 

Wellbuilt

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Yes 12v is working agents you .
you can use twice as much solar power with 24 volt system
most charge controllers work for 12/24 volts.
I have a 80 amp charge controller that can take 4000watts .
a good controller can be over paneled .
 

Cheesemaker

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Yes 12v is working agents you .
you can use twice as much solar power with 24 volt system
most charge controllers work for 12/24 volts.
I have a 80 amp charge controller that can take 4000watts .
a good controller can be over paneled .

Thanks, but If we changed to 24. V, would we need a new inverter?

And your set up , sounds like you are a business user?
 
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Cheesemaker

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Here is the technical spec for our 330 W. solar panel.
 

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Cheesemaker

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The guy says the 30a. controller is in the same style and brand as the one above., it is $150
 

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sunshine_eggo

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Vmp=41.3, so that's the voltage the panel needs to work at for max power.

330W/12V = 27.5A

A 30A controller will do it.

If you add additional panels, you will need a larger controller.

Consider that you are likely going to get 3X the solar you had with the PWM controller.

Thanks, but If we changed to 24. V, would we need a new inverter?

Per my post above, you would need a 24V inverter.
 

Wellbuilt

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That’s no good you need a mppt unit

Yes new inverter would be necessary .

My 80 amp fm80 controller will only handle 1000watts of solar @12 2000watts at 24 volts and 4000watts at 48 volt .
My place is not in a solar friendly area .
my panels where snow covered for 10 weeks last winter the pic is the first good snow .
Solar guys never talk of the snow or cloudy days🤷‍♂️
Really at the end of the day you don’t have enough power coming in to reliably run your frig
and running down to 50% over nite will kill the batteries fast Then taking them down over nite and not getting power the next day they will start to die .☹️
to stay at 12 volt you need a large charge controller 40 amps will give you 500watts of solar power .
This could work in your area if it’s not to cloudy In the rainy season .
Then you are going to add more loads ☹️
As is you can run your lites and fam and small radio but no frig .
I’ve lived with a 230 ah 12v system for years so I’m not guessing there are to many variables and you can’t turn off a frig if you run out of power .


6365503C-91CD-45A6-B64D-A2E0BC6790D4.jpeg
 

Cheesemaker

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Vmp=41.3, so that's the voltage the panel needs to work at for max power.

330W/12V = 27.5A

A 30A controller will do it.

If you add additional panels, you will need a larger controller.

Consider that you are likely going to get 3X the solar you had with the PWM controller.



Per my post above, you would need a 24V inverter.


Thanks, you say "a 30a controller will do it", but it means we won't be able to add more panels ? Maybe I need to ask him the price of a 60a or 80a controller. :)
 

Cheesemaker

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That’s no good you need a mppt unit

Yes new inverter would be necessary .

My 80 amp fm80 controller will only handle 1000watts of solar @12 2000watts at 24 volts and 4000watts at 48 volt .
My place is not in a solar friendly area .
my panels where snow covered for 10 weeks last winter the pic is the first good snow .
Solar guys never talk of the snow or cloudy days🤷‍♂️
Really at the end of the day you don’t have enough power coming in to reliably run your frig
and running down to 50% over nite will kill the batteries fast Then taking them down over nite and not getting power the next day they will start to die .☹️
to stay at 12 volt you need a large charge controller 40 amps will give you 500watts of solar power .
This could work in your area if it’s not to cloudy In the rainy season .
Then you are going to add more loads ☹️
As is you can run your lites and fam and small radio but no frig .
I’ve lived with a 230 ah 12v system for years so I’m not guessing there are to many variables and you can’t turn off a frig if you run out of power .


That's a very nice place you got there though? Have you thought of wind power?
 

sunshine_eggo

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Thanks, you say "a 30a controller will do it", but it means we won't be able to add more panels ? Maybe I need to ask him the price of a 60a or 80a controller. :)

That's going to get expensive.

At some point, you need to consider if 24V makes more sense. That doubles the wattage the MPPT can deliver...

12V * 30A = 360W
24V * 30A = 720W

At that point, you have to change your inverter, so:

Option 1, stick with 12V:
Need new 30A charge controller with each 330W panel added.
Cost: X ($120 + cost of panel to get to 660W)

Option 2, move to 24V:
No cost to add a 330W panel
Need new 24V inverter
Cost: Y (cost of inverter + cost of panel to get to 660W)
Side benefit: Additional 30A charge controllers allow you to add 2X 330W panels.
 
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