What is Shade Mitigation Factor (SMF) for microinverters? (OpenSolar 1.0)

Microinverters (and DC Optimisers) are ideal for conditions where the modules are partially shaded during a time period of operation. They have the potential to recover the shading losses with respect to central or string to a certain factor that is known as Shade mitigation factor (SMF).  

SMF represents the annual percentage of shading losses that can be recovered through the use of distributed electronics (microinverters) in partially shaded PV systems. The SMF can be used to calculate an updated shade loss term by the following equation [1]:

Shading Loss (new) = Shading Loss (%)  x (1 − SMF)

OpenSolar assumes a default SMF value of 0.33 based on the recommendation provided here.

[1] More information about this can be found on the NREL Website: Modeling Microinverters and DC Power Optimizers in PVWatts. 

References:

1. Solar Edge. (n.d.). Estimating Energy in PVWatts. (Application Note). Retrieved from http://www.solaredge.com/files/pdfs/simulating_solaredge_pv_watts_app_note.pdf
2. Deline, C.; Meydbray, J.; Donovan, M. (2014). Photovoltaic Shading Testbed for Module Level Power Electronics: 2014 Update, NREL Report No. TP-5J00-62471. Retrieved from http://www.nrel.gov/docs/fy14osti/62471.pdf
3. MacAlpine, S., Erickson, R., & Brandemuehl, M. (2013). Characterization of power optimizer potential to increase energy capture in photovoltaic systems operating under nonuniform conditions. IEEE Transactions on Power Electronics, 28(6), 2936-2945.
4. Hanson, A. J.; Deline, C. A.; MacAlpine, S. M.; Stauth, J. R.; Sullivan, C. R. (2014). Partial-Shading Assessment of Photovoltaic Installations via Module-Level Monitoring. IEEE Journal of Photovoltaics. Vol. 4(6), November 2014; pp. 1618-1624.