is midnite solar is the best charge controller in the world?

[James1079]

I guess Morningstar says three is optimal

[littleharbor]

Okay well this is just kind of temporary to keep the battery stopped up until I set up the full system but in full sun I am reading 65 volts coming into the controller fromthe two panels. I guess I don't see nominal voltage in the data sheet I just assumed that they were 24 volt panels. Are all 60 cell panels only 20 volts?

Yes, they are considered 20 volt nominal. That being said there some higher wattage (300+ watts) 60 cell panels that are high enough voltage to effectively charge a 24 volt bank. You need to keep in mind that the voltage ratings and the real world voltage are two different things. In cold, clear sunny conditions your voltage can and will exceed the panel's rating but hot sunny conditions will drive their output voltage down and 60 cell panels voltage will be too low for 24 volt charging.

[James1079]

For their MPPT controller? Regardless your panels aren't 24 volt panels. They are considered 20 volt nominal so 2 in series is a 40 volt nominal voltage which will not PROPERLY charge a 48 volt bank. 2 in series will keep your batteries from discharging below a certain point, but won't top off or equalize them. If you don't mind replacing your batteries on a regular basis , then, by all means stay with 2 in series.

Yes I have the TriStar mppt 60 amp model

[James1079]

Okay well this is just kind of temporary to keep the battery stopped up until I set up the full system but in full sun I am reading 65 volts coming into the controller fromthe two panels. I guess I don't see nominal voltage in the data sheet I just assumed that they were 24 volt panels. Are all 60 cell panels only 20 volts?

[littleharbor]

I am watching the Morningstar training video and it mentions to reach 99% efficiency you need 48 volts in and 48 volts out

For their MPPT controller? Regardless your panels aren't 24 volt panels. They are considered 20 volt nominal so 2 in series is a 40 volt nominal voltage which will not PROPERLY charge a 48 volt bank. 2 in series will keep your batteries from discharging below a certain point, but won't top off or equalize them. If you don't mind replacing your batteries on a regular basis , then, by all means stay with 2 in series.

[James1079]

Yes.

I am watching the Morningstar training video and it mentions to reach 99% efficiency you need 48 volts in and 48 volts out

[littleharbor]

Yes.

[James1079]

Being 60 cell panels their voltage isn't high enough to charge a 48 volt battery when only 2 in series. 3 in series is really your only option for a 48 volt system.

I have just two panels connected right now until the weather's nicer to mount the rest and it seems to be charging the battery. do I need to hook up one more

[littleharbor]

Being 60 cell panels their voltage isn't high enough to charge a 48 volt battery when only 2 in series. 3 in series is really your only option for a 48 volt system.

[James1079]

So two would be the most efficient? but 3 would save me some wire and breakers?

[Mike90250]

Sorry, lost count of all the panels, so yes, 3 series in a string would be under the kill voltage of the Controller. 2 in a string would be marginal to EQ a 48V bank.

[James1079]

I will say with GREAT confidence, that your 4 panels in series will FRY a controller with a 150V limit.

Your best option is 2 panels in series, parallel with the other 2 series panels, gives 70V, well under the kill voltage. and enough voltage to charge 24V bank.

I have 12 panels total and a 48 volt battery Bank. I was thinking three panels in series on four strings?

[Mike90250]

I will say with GREAT confidence, that your 4 panels in series will FRY a controller with a 150V limit.

Your best option is 2 panels in series, parallel with the other 2 series panels, gives 70V, well under the kill voltage. and enough voltage to charge 24V bank.

[James1079]

Safer to assume no voltage margin. Figure out the coldest temperature the panels will _ever_ see (weather stations usually have almanac data for this) then figure out what Voc they will produce based on the temperature coefficient (listed in the panel's data sheet.) That will give you max voltage.

I'm not sure what the equation is for that can you show me? My closest weather station is fox farms in Portland Michigan

[jflorey2]

at four panels that comes out to 148.4 which is pretty darn close to 150. I think the true question is how much error margin does the Trina solar panel or the Morningstar 60 give me. I'm on the 43-degree latitude in Michigan and once in a blue moon we have some pretty clear cold mornings

Safer to assume no voltage margin. Figure out the coldest temperature the panels will _ever_ see (weather stations usually have almanac data for this) then figure out what Voc they will produce based on the temperature coefficient (listed in the panel's data sheet.) That will give you max voltage.