Solar unit voltage vs panel voltage

[Jamasarah]

I have a 48V MPPT unit, and my solar panels are 12V…will this work, if not why?

 

[pvgirl]

MPPT change controllers need at least 5v above battery voltage to work, with for a 48volt nominal system would be as much as 63volts at the maximum battery voltage. You can put multiple 12v panels in series to up the voltage to work with a 48 volt system. You will need to check your panels specs for Vmp to calculate the voltage you will get. A random 12 volt I looked at has a Vmp of 20.4volts, 4 in series would produce 81.6 volts which is plenty for a 48volt system.

 

[MichaelK]

Flip one of your panels over and look at the spec sheet pasted on the back. It will have numbers for Voc, Vmp, Isc, and Imp. Those are the specs of what the ideal output is going to be.

Let's say after getting the numbers, you tell us the Vmp is 18.0V, and the Voc is 21.0V. Those are realistic numbers for 12V panels. For the MPPT to function properly, it must receive incoming voltage that's about 30% higher than the charging voltage (says Midnight solar). How much voltage the battery wants to charge at is dependent partially on it's chemistry. In general, lead-acid wants a bit more voltage, maybe in the 59-64V range, while Li might be a bit lower.

So, you'd need at least four 18V panels in series to make the required voltage, and maybe 5 in series depending on how efficient your controller is? Can you give us the brands/models of the panels, batteries, and controller you have. Keep in mind also that some MPPT controllers have voltage limits as low as 100V, so knowing the brands/models here is quite important. Putting too many panels in series could potentially fry your controller. The details here will guide you through the proper configuration of your system.

 

[Jamasarah]

MPPT change controllers need at least 5v above battery voltage to work, with for a 48volt nominal system would be as much as 63volts at the maximum battery voltage. You can put multiple 12v panels in series to up the voltage to work with a 48 volt system. You will need to check your panels specs for Vmp to calculate the voltage you will get. A random 12 volt I looked at has a Vmp of 20.4volts, 4 in series would produce 81.6 volts which is plenty for a 48volt system.

I have a 48V MPPT unit, and my solar panels are 12V…will this work, if not why?

my unit it is a MPP solar hybrid LV 6048 inverter/charger
I’m getting 60v from 16, 250W panels. I believe the panels are in parallel to the end and then hooked up as series… But it has been 3 1/2 years, and I am really ignorant when it comes to electricity and solar.
Also, I don’t think my 4, 12V batteries are holding a charge for very long after the sun goes down, (about 2 to 3 hours if I’m lucky)

 

[Jamasarah]

Flip one of your panels over and look at the spec sheet pasted on the back. It will have numbers for Voc, Vmp, Isc, and Imp. Those are the specs of what the ideal output is going to be.

Let's say after getting the numbers, you tell us the Vmp is 18.0V, and the Voc is 21.0V. Those are realistic numbers for 12V panels. For the MPPT to function properly, it must receive incoming voltage that's about 30% higher than the charging voltage (says Midnight solar). How much voltage the battery wants to charge at is dependent partially on it's chemistry. In general, lead-acid wants a bit more voltage, maybe in the 59-64V range, while Li might be a bit lower.

So, you'd need at least four 18V panels in series to make the required voltage, and maybe 5 in series depending on how efficient your controller is? Can you give us the brands/models of the panels, batteries, and controller you have. Keep in mind also that some MPPT controllers have voltage limits as low as 100V, so knowing the brands/models here is quite important. Putting too many panels in series could potentially fry your controller. The details here will guide you through the proper configuration of your system.

Well I’m 76 yrs old, so they’ll be no turning over of a panel and reading anything on it? I believe they probably weigh more than I do ha ha, and I wouldn’t understand what all those figures meant anyways.

So it sounds like I may have bought the wrong panels 3 1/2 years ago I should have bought 48 V, but I had to build a cabin off grid in the high desert with what I had to work with.
Now I’m kind of stuck with 4 batteries that are going kaput, and a system that I don’t understand.
I did purchase a EF Delta max 2,600 and it is working good, I just plug it in to the MPP system which gives me max 860W, until 2 hrs before the sun goes down, and then I unplug my unit from the MPP unit, otherwise, the MPP unit will shut down from low batteries

The DMax will stay charged till morning at approx 40- 60%, and when the sun comes up, I just flip on the power strip, and it charges my DMax up in about 3 hrs.

At this time, my goal is to have a refrigerator & a heater, and stop using my old cook wood stove for heating.
if anybody has any suggestions, that would be ? good.
My thoughts are…biting the bullet, and saving for a 400W bifacial polycrystalline panels and 2 batteries from EF- DMax so they match up with my set up?

 

[MichaelK]

So it sounds like I may have bought the wrong panels 3 1/2 years ago I should have bought 48 V, but I had to build a cabin off grid in the high desert with what I had to work with.
Now I’m kind of stuck with 4 batteries that are going kaput, and a system that I don’t understand.
?

Well, no, not really. Do back and read the third paragraph of post #3 again. Panels can be wired in series to reach any voltage you want/need. You are NOT doing your proper research.

I did purchase a EF Delta max 2,600 and it is working good, I just plug it in to the MPP system which gives me max 860W, until 2 hrs before the sun goes down, and then I unplug my unit from the MPP unit, otherwise, the MPP unit will shut down from low batteries

This is the hallmark of poor design. You have to shut the system down for two reasons. First, you bought an AiO unit with a very high background idle draw, which is discussed in great detail here, and secondly, you did not plan around the extra draw that is draining the batteries. Again, lack of research. Do your homework.

My thoughts are…biting the bullet, and saving for a 400W bifacial polycrystalline panels and 2 batteries from EF- DMax so they match up with my set up

Take a look at Craigslist for panels. You are likely to find many different panel types that can be wired in series and parallel to get exactly the specifications you want. And for significantly less money.