DC/AC Ratio Calculator

Calculator Inputs

Use direct DC sizing or calculate from module details.

Input method

Choose how to define DC nameplate power.

DC array size (kWdc)

Sum of module nameplate ratings at STC.

Module wattage (W)

Use the module’s nameplate power.

Module count

Total installed modules feeding the inverter(s).

Inverter AC rating (kWac)

Sum of inverter AC nameplate ratings.

Target ratio band

A quick check against your design target.

System losses (%)

Soiling, wiring, mismatch, inverter DC losses, etc.

Temperature coefficient (%/°C)

Typically negative for PV modules.

Cell temperature (°C)

Use expected operating cell temperature.

Reference temperature (°C)

Common reference is 25°C (STC).

Inverter max DC input (kWdc) (optional)

Used only for warnings and checks.

Tip: For multi-inverter systems, enter total AC rating and total DC feeding them.

Scenario	DC (kWdc)	AC (kWac)	Losses (%)	Cell Temp (°C)	Nameplate Ratio	Effective Ratio	Risk
Rooftop PV	55.0	50.0	14	45	1.100	0.946	Low
Commercial Array	120.0	100.0	12	40	1.200	1.069	Moderate
Utility Block	156.0	120.0	10	35	1.300	1.190	Moderate

Example assumes temperature coefficient -0.35 %/°C and reference 25°C.

Nameplate DC/AC ratio:

DC/AC = P_DC,STC / P_AC

Temperature factor:

f_T = 1 + (γ/100) × (T_cell − T_ref)

Effective DC power:

P_DC,eff = P_DC,STC × (1 − L/100) × f_T

Effective DC/AC ratio:

(DC/AC)_eff = P_DC,eff / P_AC

Use this for preliminary sizing. Confirm inverter DC limits and MPPT windows from datasheets.

Example Data Table