How can a horizontal panel produce more per m2 of panel than a tilted panel (latitude value)?

[RicardoGomesIST]

Hi,
I am using CEA to calculate PV panel potential. I am testing a very simple case for Lisbon (latitude =38º) - just one building with surrounding buildings lower than it.

I created two scenarios one with:

• tilt=1º - (as 0 is not possible) so horizontal

and other with:

• tilt= 30º

Assuming that the tilted panels face south, I was expecting that the PV production (kWh/m2) would be higher for the tilted than for the horizontal.

What I get was:

• tilt=1º - (as 0 is not possible) so horizontal

<style> </style>

Name	PV_roofs_top_E_kWh	E_PV_gen_kWh	radiation_kWh	PV_roofs_top_m2	Area_PV_m2
B1000	134821.9	134821.9	1046941	655.66	655.66

Doing the calculation:
kWh/m2=E_PV_gen_kWh /Area_PV_m2= 205.6

--

• tilt= 30º

<style> </style>

Name	PV_roofs_top_E_kWh	E_PV_gen_kWh	radiation_kWh	PV_roofs_top_m2	Area_PV_m2
B1000	52345.78	52345.78	584711.3	365.92	365.92

Doing the calculation: kWh/m2=E_PV_gen_kWh /Area_PV_m2= 143.03

---

So I ran this and just changed the tilt angle: