• $C_{{\mathrm{CO}}_2}$

  CO₂ savings [g CO₂/km]

• CO₂

  Carbon dioxide

• CF

  Conversion factor (l/100 km) — (g CO₂/km) [gCO₂/l] as defined in Table 3

• M

  Mean annual mileage [km/year] as defined in Table 4

• $\overline{{\mathrm{mP}}_P}$

  Measured average solar PV roof peak power output [W]

• n

  Number of measurements of the solar PV roof peak power output, which is at least 5

• SCC

  Solar correction coefficient [-] as defined in Table 1

• $s_{C_{{\mathrm{CO}}_2}}$

  Statistical margin of the total CO₂ savings [g CO₂/km]

• S_IR

  Yearly European mean solar irradiation [W/m²], which is 120 W/m²

• S_{IR_STC}

  Global irradiation at Standard Test Conditions (STC) [W/m²], which is 1 000 W/m²

• $s_{\overline{{\mathrm{mP}}_P}}$

  Standard deviation of the arithmetic mean of the solar PV roof peak power output [W]

• UF_IR

  Usage factor (shading effect), which is 0,51

• V_Pe

  Consumption of effective power [l/kWh] as defined in Table 2

• 

  Sensitivity of calculated CO₂ savings related to the average solar PV roof peak power output

• ΔCO_2m

  CO₂ correction coefficient due to the extra mass of the solar system [g CO₂/km] as defined in Table 5

• Δm

  Extra mass due to the installation of the solar system [kg]

• η_A

  Alternator efficiency [%], which is 67 %

• η_SS

  Solar system efficiency [%], which is 76 %

• Φ

  Lengthwise inclination of the solar panel [°]

Index (i) refers to measurement of the PV roof peak power output

$C_{{\mathrm{CO}}_2}=S_{\mathrm{IR}}\times {\mathrm{UF}}_{\mathrm{IR}}\times {\eta }_{\mathrm{SS}}\times \frac{\overline{{\mathrm{mP}}_P}}{S_{\mathrm{IR\_STC}}}\times \mathrm{SCC}\times \frac{V_{\mathrm{Pe}}}{{\eta }_A}\times \frac{\mathrm{CF}}{M}\times \mathrm{cos\Phi }-{\mathrm{\Delta CO}}_{\mathrm{2m}}$

Where:

• $C_{{\mathrm{CO}}_2}$

  CO₂ savings [g CO₂/km]

• S_IR

  Yearly European mean solar irradiation [W/m²], which is 120 W/m²

• UF_IR

  Usage factor (shading effect) [-], which is 0,51

• η_SS

  Efficiency of the photovoltaic system [%], which is 76 %

• $\overline{{\mathrm{mP}}_P}$

  Measured average PV roof peak power output [W]

• S_{IR_STC}

  Global irradiation at Standard Test Conditions (STC) [W/m²], which is 1 000 W/m²

• SCC

  Solar correction coefficient [-] as defined in Table 1. Total available storage capacity of the battery system or the SCC value is to be supplied by the vehicle manufacturer.

  Table 1Solar correction coefficient

  Total available storage capacity of (12 V) battery system/average PV roof peak power output [Ah/W]10	0,10	0,20	0,30	0,40	0,50	0,60	> 0,666
  Solar correction coefficient (SCC)	0,481	0,656	0,784	0,873	0,934	0,977	1

  10

  The total storage capacity includes a mean usable storage capacity of the starter battery of 10 Ah (12 V). All values refer to a mean annual solar radiation of 120 W/m², a shading share of 0,49 and a mean vehicle driving time of 1 hour per day at 750 W electric power requirement.

• V_Pe

  Consumption of effective power [l/kWh] as defined in Table 2

  Table 2Consumption of effective power

  Type of engine	Consumption of effective power (VPe)[l/kWh]
  Petrol	0,264
  Petrol Turbo	0,280
  Diesel	0,220

• η_A

  Efficiency of the alternator [%], which is 67 %;

• CF

  Conversion factor (l/100km) — (g CO₂/km) [gCO₂/l] as defined in Table 3

  Table 3Fuel conversion factor

  Type of fuel	Conversion factor (l/100 km) — (g CO2/km) (CF)[gCO2/l]
  Petrol	2 330
  Diesel	2 640

• M

  Mean annual mileage [km/year] as defined in Table 4

  Table 4Mean annual mileage for M₁ vehicles

  Type of fuel	Mean annual mileage (M) [km/year]
  Petrol	12 700
  Diesel	17 000

• Φ

  Lengthwise inclination of the solar panel [°]. This value is to be supplied by the vehicle manufacturer

• ΔCO_2m

  CO₂ correction coefficient due to the extra mass of the solar roof and, where applicable, the additional battery and other appliances needed specifically for the conversion of the solar energy into electricity and its storage [g CO₂/km] as defined in Table 5.

  Table 5CO₂ correction coefficient due to the extra mass

  Type pf fuel	CO2 correction coefficient due to the extra mass (ΔCO2m)[g CO2/km]
  Petrol	0,0277 · Δm
  Diesel	0,0383 · Δm

In Table 5 Δm is the extra mass due to the installation of the photovoltaic system, composed by the PV roof and, where applicable, the additional battery and other appliances needed specifically for the conversion of the solar energy into electricity and its storage.

In particular, Δm is the positive difference between the mass of the photovoltaic system mass and the mass of a standard steel roof. The mass of a standard steel roof is assumed equal to 12 kg. In case the weight of the solar system is lower than 12 kg, no correction for the change in mass has to be made.

$s_{\overline{{\mathrm{mP}}_p}}=\sqrt{\frac{\sum _{i=1}^n{\left({\mathrm{mP}}_{P_i}-\overline{{\mathrm{mP}}_P}\right)}^2}{n\left(n-1\right)}}$

Where:

• $s_{\overline{{\mathrm{mP}}_p}}$

  Standard deviation of the arithmetic mean of the peak power output [W]

• ${\mathrm{mP}}_{P_i}$

  Measurement value of the peak power output [W]

• $\overline{{\mathrm{mP}}_P}$

  Arithmetic mean of the peak power output [W]

• n

  Number of measurements of the peak power output, which is at least 5

The standard deviation of arithmetic mean of the PV roof peak power output leads to a statistical margin in the CO₂ savings $\left(s_{C_{{\mathrm{CO}}_2}}\right)$. This value is to be calculated in accordance with Formula 3.

$\mathrm{MT}\le C_{{\mathrm{CO}}_2}-s_{C_{{\mathrm{CO}}_2}}$

Where:

• MT

  Minimum threshold [g CO₂/km], which is 1 g CO₂/km

• $s_{C_{{\mathrm{CO}}_2}}$

  Statistical margin of the total CO₂ savings [g CO₂/km]

Where the CO₂ emission savings, as a result of the calculation using Formula 4, are below the threshold specified in Article 9(1) of Implementing Regulation (EU) No 725/2011, the second subparagraph of Article 11(2) of that Regulation shall apply.