GT Only vs. GT with Battery Backup
DC Builders
Registered Users Posts: 13 ✭
If I want to run a 48 volt battery UPS GT system, with 14 210 WATT Solar Panels, Vmp 26.6; Imp 7.90.
Instead of one string at 372 Volts, 7.9 amps to the inverter for GT Only........
I would run 7 strings of 2 panels for 53.2 volts and 55.3 amps to my charge controller then to batteries and on to inverter?
What is the best way to do this?
Thanks
Dan
Instead of one string at 372 Volts, 7.9 amps to the inverter for GT Only........
I would run 7 strings of 2 panels for 53.2 volts and 55.3 amps to my charge controller then to batteries and on to inverter?
What is the best way to do this?
Thanks
Dan
Comments
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Re: GT Only vs. GT with Battery Backup
Is there anyway you can- run 15 panels--2x string of three
- run a XW 4024 hybrid inverter
Your 2x Vmp 26.6 = 53.2 vdc on a cool sunny day... On a windless sunny 95F summer day--your panel Vmp is going to be around 42 volts--way too low to charge the battery bank and run Grid Tie.
So, either you need 3 panels in series or a Vbatt of 24 volts to operate with two panels in series.
Where will the installation be, what brand/model of panels, what Hybrid inverter and MPPT Charge Controller are you thinking of using?
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: GT Only vs. GT with Battery Backup
Thanks Bill,
I'll check into it...I am on the right track lowering the voltage?
I deleted my post about single line drawing. It was too snobbish.
We are here to help and get help, not to turn solar energy into a litigious night mare.
Thanks again,
Dan -
Re: GT Only vs. GT with Battery Backup
It depends on what you need...
A "typical" GT inverter operates around 200-600 VDC input.
A typical Hybrid inverter runs on a 24 or 48 volt battery bank. And the typical MPPT charge controller runs on Vbatt-Charging+2 volts to around 140-150 VDC maximum.
And, from what I have looked at the Vmp/Voc specs. of solar panels--Vmp hot : Voc cold (minimum operational to open circuit below freezing voltage) range was almost 1:2...
It works out, roughly that Vmp nominal at STC is around ~100 VDC maximum. If Vmp>100 VDC by much--sub zero open circuit voltage may exceed 150 VDC. And for hot weather/climate on a battery bank--you are looking at nominal temperature Vmp of the string of around 72 VDC minimum... (based on 48 volt bank).
At least for now (until the whole Xantrex name change / website update is done)--this link still works to configure the strings for the XW 60 Amp charge controller.
There are other inverters / hybrid inverters (in and outside the US)--Do you have a particular hardware configuration you are looking at?
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: GT Only vs. GT with Battery Backup
Bill,
Class had holiday this weekend. I am a little a head of what we have been studying.
Can see that once batteries are introduced the situation is more complex.
Checked that 4024 you recommended it looks like it does a lot.
I am just finally understanding the algebra on kWh/battery voltage.
volts * Amp hrs (watt hours)
volts
volts over volts = 1, so answer is in Amp Hours
Not stupid just slow,
Dan
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