PV System Calculations

Equations:

Watts (Power) = Volts (Pressure) x Amperage/Current (Flow)
W=V x A

Watt-hours = Watts x hours
WH= W x hrs

Amp-hours = Amps x Hours (Usually measured at the 20hr discharge rate)
AH=A x hrs

Watts add in series or parallel
Volts add in series
Amps and Amp-hours add in parallel

Parallel connection is PLUS to PLUS and MINUS to MINUS
Series is PLUS to MINUS

System 1-Hardisky
1a) PV array 1 and 2 measure 337V nominal. There are 20 PV panels in each array.
Each array consists of two strings of 10 panels. Are the 10 PV panels connected in series or parallel?

1b) The two strings of 10 panels are connected together in the combiner box. Are they connected in series or parallel?

1c) Based on this information, what is the voltage of each string of 10 panels?

1d) Based on this information what is the nominal (normal) voltage of each panel?

2a) Each panel in array 1 or 2 is 210 Watts. How many watts in each string of 10 panels?

2b) Based on this information and knowing the voltage of each string of 10 panels, what is the current between each string of 10 panels and the combiner box?

3a) Each PV Array connects to a separate inverter. Knowing the Power (Watts) and AC voltage of each inverter, what is the current (Amps) on the AC side of the inverter when operating at maximum power?

3b) If the inverters were rated for 120AC instead of 240AC what would the current (Amps) be on the AC side at max power?

4) Is this system off-grid or net-metered?

System 2-Marsden
1) The inverters are rated for 54VDC max input, and 22-40VDC maximum powerpoint tracking (MPPT) range.

The PV panels BP175B are rated at 24V nominal, but 35.8 at max power (I looked it up). This is in the correct range for the micro-inverters (22-40V).

Since the PV panels are rated for 175W each, what is the current (amps) at max power of each PVpanel?

2) What is the total max power rating of the 21 enphase micro-inverters?

3) What is the total power output of the 21 PV panels?

4) What is the AC amperage at the junction box for PV Array1?

5) What is the AC amperage at the junction box for PV Array2?

System 3-Ackerman
1a) The PV array is wired for what voltage?
1b) Each string of 4 PV panels is wired in series or parallel?
1c) What is the Wattage of each string of 4 PV panels?
1c) What is the amperage produced by each string of 4 PV panels?

2a) In the combiner box each string of 4PV panels is connected to the other strings in series or parallel?
2b) Therefore what is the total current between the combiner box and the controller?

3a) The batteries are wired for what voltage?
3b) Therefore the controller has input of ___volts and an output of ___volts?

4) What is the total Watt-hours of the battery pack?

5) What is the amperage between the batteries and the inverter DC input at inverter max power?

6) What is the AC amperage on the inverter AC output at inverter max power?

System 4-Larch Company
1) What is the nominal voltage of each PV panel in PV Array #!?

2) What is the amperage of each string of 10 PV panels in PV Array #!?

3) What is the amperage between the combiner box and the Fronius Inverter?

4) What is the AC amperage on the Fronius AC output at max power?

5) In PV array #2: What is the amperage from each string of 3 panels to the combiner box?

6) In PV array #2: What is the amperage from the combiner to the charge controller?

7) What is the amperage between the batteries and the two inverters, before the wires split to feed the 2 inverters?

8) What is the AC amperage on the output of each Outback inverter at max power at 120VAC?