|
| Author |
Message |
hamish
Member
|
# Posted: 21 Sep 2016 10:38pm
Reply
Ok, before I jump on board the MMPT quest.....
Are max solar input ratings for MPPT chargers based upon battery bank voltage?
I want to use series/parallel 2x 100W 12v panels, in series then paralleled with another string of 2x100W 12v panels.....does my actual pv input equal 200W or still 400W?
With respect to using say a Renogy 4210RN 40A Mppt for example?
|
|
MtnDon
Member
|
# Posted: 21 Sep 2016 11:06pm - Edited by: MtnDon
Reply
Quoting: hamish I want to use series/parallel 2x 100W 12v panels, in series then paralleled with another string of 2x100W 12v panels.....does my actual pv input equal 200W or still 400W?
Watts are watts. Add up the watts and that is what you have. In this case 400 watts. It does not matter if they are all in series or all in parallel or a series/parallel mix. Watts are watts.
Watts = volts x amps. Try it with all the panels in series, all in parallel or mixed. The volts and amps on each example changes, but when you do the equation volts x amps = watts the watts are the same.
When a charge controller has the ability to operate on more than one battery voltage (12, 24, 48...) the total number of watts input that a controller can handle is changes. As the voltage of the battery bank increases, the amperage output of the controller remains the same. Therefore the total wattage input increases as the battery bank voltage increases. That is one of the advantages or running 24 or 48 volt battery banks. The same charge controller can handle more watts, more panels.
Of course 4 x 12 volt panels in parallel will not be able to charge a 24 volt battery. Not enough volts. That's where the 2S/2P configuration would be used.
Read the controller specs carefully. Look at the battery voltages that the controller can do, check the maximum input voltages against the Voc x 1.25, check amps, watts and so on.
Hope that helps you.
|
|
groingo
Member
|
# Posted: 22 Sep 2016 11:23am
Reply
Unless you are planning to expand your system soon or the near future the 4210 is overkill, a good PWM Controller with LED readout will do quite well all for under $50.00 and gives you the ability to custom adjust to fit your power needs.
When you reach 800 watts and up you may consider MPPT.
|
|
creeky
Member
|
# Posted: 23 Sep 2016 11:16am
Reply
Quoting: hamish Are max solar input ratings for MPPT chargers based upon battery bank voltage
Yes.
From what you describe you'll have 400w at 24v nominal.
What is your battery voltage? And what is the open circuit voltage of your panels?
If I might make two points.
1) make sure your panel voltage is well above your battery voltage. Ie. A 24 volt battery pack should see panel open circuit voltage at 32v or higher. 48 is even better.
2) have you considered getting two panels at 200w each. They will be much cheaper. Or even 250s? 2@250 are probably a hundred bucks cheaper and will be of better quality than 4 100s
MPPT pays for itself. You'll be garnering a lot more power during cloud etc with mppt. And it allows you to run higher voltage panels: which equals lower amps: which means thinner/cheaper transmission lines - or greater distances from your controller. Higher voltage panels are also cheaper per watt.
|
|
|
