Sizing Widespread Photo voltaic Cost Controllers
All renewable power (RE) methods with batteries ought to embrace a cost controller. On this article we’ll principally be referring to photo voltaic cost controllers . Cost controllers forestall battery overcharging and in addition forestall the batteries from sending their cost again by means of the system to the charging supply (i.e., the photo voltaic panels). Consider a photo voltaic cost controller as a battery nurse—its job is to watch the battery financial institution, feeding it what it wants and checking its very important indicators. Since a photo voltaic controller does its work in line between the photo voltaic panel array and the batteries, it will make sense that its choice and sizing could be influenced by these parts. And that is precisely the case.
Voltage and amperage (or present) are the parameters we use in photo voltaic cost controller sizing. The photo voltaic controller should be able to accepting the voltage and present produced by the DC supply (normally photo voltaic panels) and delivering the right voltage and present to the batteries. This example would possibly make you assume that the DC supply, cost controller and batteries should all share a typical voltage. Whereas that’s one system design technique utilized in many installations, it isn’t the one one. Extra on the alternate options in one other article. For now, it is one voltage for everybody!
Technically talking, the DC supply should all the time have a better working voltage than the battery financial institution to ensure that present to move from one to the opposite. A helpful method to bear in mind this truth is the assertion, “curent flows downhill.” For the aim of this dialogue, we’ll use nominal voltage which implies frequent battery voltages. Nominal voltage on this sense is synonymous with battery voltage. Since batteries (the place they’re used) are in some ways the center of an RE system, we will name the financial institution’s voltage the system voltage. The system voltage chosen for any given set up is normally, although not all the time, decided by the battery financial institution required by the appliance; the inverter, if one is used, may even affect the selection of system voltage.
Sizing comes all the way down to this: there’s the fast methodology, which is able to very possible give a suitable, if maybe outsized outcome, however will not describe the why right here – we’ll simply present you the steps.
Brief Technique for Sizing Photo voltaic Cost Controllers
- For PWM and PWM shunt photo voltaic controllers, choose one that’s rated at your system voltage (similar nominal voltage during the system).
- Divide photo voltaic panel array whole wattage by system voltage.
- Add 20% as a security margin (i.e., (results of Step 2) X 1.2).
- Choose a photo voltaic controller rated at or above the results of Step 3.
Instance of the Brief Technique
- Two 125W, 12V nominal modules. System is 250 W, 12 Volt nominal. Photo voltaic cost controller will probably be 12 Volts.
- 250 ÷ 12 = 20.83
- 20.83 * 1.2 = 24.996 amps
- You could possibly use a Xantrex C35, a 35 amp photo voltaic cost controller; or a Morningstar Prostar 30, a 30 amp solar charge controller , for instance. Any 12 volt photo voltaic controller better than 25 amps will work.