10 Module Deployment and Energy Rating
259
C s (t) =
1000
G(t)
λ 1
300 S R mod (λ)G(λ, t)dλ
λ 1
300 S R mod (λ)G AM1.5 (λ)dλ
,
(10.8)
where SR mod (λ) is the spectral responsivity of the module, G(λ, t) and G AM1.5 (λ) are
the measured in-plane global spectral irradiance at time t and the standard AM1.5
spectral irradiance, respectively.
10.2.5 Calculation of the Annual Energy Output of a PV
Module in Seven Steps
We now have all the inputs needed to perform the calculation of the annual energy
output of a PV module in the field, knowing:
• the in-plane global irradiance as a function of time, G(t);
• its direct component, B(t);
• the in-plane global spectral irradiance as a function of time, G(λ, t);
• the PV module temperature as a function of time, T (t), which can be measured
directly from the field or calculated via the Faiman formula (10.4);
• the PV module efficiency as a function of irradiance and temperature, η(G, T );
• the fitting parameter a r for the angular transmittance τ (θ );
• the module tilt β;
• the spectral responsivity of the PV module, SR mod (λ);
• the module area A.
The annual energy output can then be calculated with the following seven steps:
1. calculate the in-plane diffuse irradiance D(t) = G(t) − B(t);
2. obtain the corrected in-plane direct and diffuse irradiances for the angle of
incidence effect (B corr,AOI (t) and D corr,AOI (t));
3. calculate the corrected in-plane global irradiance for angle of incidence effect
G corr,AOI (t) = B corr,AOI (t) + D corr,AOI (t);
4. calculate the spectral mismatch correction factor C s (t), using (10.8);
5. calculate the spectrally corrected global in-plane irradiance G corr,AOI+s (t) =
C s (t) · G corr,AOI (t);
6. calculate the module power at time t, P(t) = G corr,AOI+s · η
G corr,AOI+s , T (t)
;
7. calculate the annual energy output via (10.3), E =
i P(t)t, where the sum
is performed over 1 year of measurements and t is a reasonably short amount
of time during which P(t) can be considered constant (t = 1 hour is a good
compromise for reliable results over 1 year of data).
259
C s (t) =
1000
G(t)
λ 1
300 S R mod (λ)G(λ, t)dλ
λ 1
300 S R mod (λ)G AM1.5 (λ)dλ
,
(10.8)
where SR mod (λ) is the spectral responsivity of the module, G(λ, t) and G AM1.5 (λ) are
the measured in-plane global spectral irradiance at time t and the standard AM1.5
spectral irradiance, respectively.
10.2.5 Calculation of the Annual Energy Output of a PV
Module in Seven Steps
We now have all the inputs needed to perform the calculation of the annual energy
output of a PV module in the field, knowing:
• the in-plane global irradiance as a function of time, G(t);
• its direct component, B(t);
• the in-plane global spectral irradiance as a function of time, G(λ, t);
• the PV module temperature as a function of time, T (t), which can be measured
directly from the field or calculated via the Faiman formula (10.4);
• the PV module efficiency as a function of irradiance and temperature, η(G, T );
• the fitting parameter a r for the angular transmittance τ (θ );
• the module tilt β;
• the spectral responsivity of the PV module, SR mod (λ);
• the module area A.
The annual energy output can then be calculated with the following seven steps:
1. calculate the in-plane diffuse irradiance D(t) = G(t) − B(t);
2. obtain the corrected in-plane direct and diffuse irradiances for the angle of
incidence effect (B corr,AOI (t) and D corr,AOI (t));
3. calculate the corrected in-plane global irradiance for angle of incidence effect
G corr,AOI (t) = B corr,AOI (t) + D corr,AOI (t);
4. calculate the spectral mismatch correction factor C s (t), using (10.8);
5. calculate the spectrally corrected global in-plane irradiance G corr,AOI+s (t) =
C s (t) · G corr,AOI (t);
6. calculate the module power at time t, P(t) = G corr,AOI+s · η
G corr,AOI+s , T (t)
;
7. calculate the annual energy output via (10.3), E =
i P(t)t, where the sum
is performed over 1 year of measurements and t is a reasonably short amount
of time during which P(t) can be considered constant (t = 1 hour is a good
compromise for reliable results over 1 year of data).