Merge pull request #358 from NREL/develop

v0.42.0 PVWatts tilt angle alignment
NREL · Mar 14, 2024 · c884e78 · c884e78 · Bill-Becker · Mar 18, 2024
2 parents 677f3d9 + ff1c984
commit c884e78
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -23,6 +23,14 @@ Classify the change according to the following categories:
     ### Deprecated
     ### Removed
 
+## v0.42.0
+### Changed
+- In `core/pv.jl` a change was made to make sure we are using the same assumptions as PVWatts guidelines, the default `tilt` angle for a fixed array should be 20 degrees, irrespective of it being a rooftop `(1)` or ground-mounted (open-rack)`(2)` system. By default the `tilt` will be set to 20 degrees for ground-mount and rooftop, and 0 degrees for axis-tracking (`array_type = (3) or (4)`)
+
+> "The PVWatts® default value for the tilt angle depends on the array type: For a fixed array, the default value is 20 degrees, and for one-axis tracking the default value is zero. A common rule of thumb for fixed arrays is to set the tilt angle to the latitude of the system's location to maximize the system's total electrical output over the year. Use a lower tilt angle favor peak production in the summer months when the sun is high in the sky, or a higher tilt angle to increase output during winter months. Higher tilt angles tend to cost more for racking and mounting hardware, and may increase the risk of wind damage to the array."
+
+
+
 ## v0.41.0
 ### Changed
 - Changed default source for CO2 grid emissions values to NREL's Cambium 2022 Database (by default: CO2e, long-run marginal emissions rates levelized (averaged) over the analysis period, assuming start year 2024). Added new emissions inputs and call to Cambium API in `src/core/electric_utility.jl`. Included option for user to use AVERT data for CO2 using **co2_from_avert** boolean. 

diff --git a/Project.toml b/Project.toml
@@ -1,7 +1,7 @@
 name = "REopt"
 uuid = "d36ad4e8-d74a-4f7a-ace1-eaea049febf6"
 authors = ["Nick Laws", "Hallie Dunham <hallie.dunham@nrel.gov>", "Bill Becker <william.becker@nrel.gov>", "Bhavesh Rathod <bhavesh.rathod@nrel.gov>", "Alex Zolan <alexander.aolan@nrel.gov>", "Amanda Farthing <amanda.farthing@nrel.gov>"]
-version = "0.41.0"
+version = "0.42.0"
 
 [deps]
 ArchGDAL = "c9ce4bd3-c3d5-55b8-8973-c0e20141b8c3"

diff --git a/src/core/pv.jl b/src/core/pv.jl
@@ -3,7 +3,7 @@
 `PV` is an optional REopt input with the following keys and default values:
 ```julia
     array_type::Int=1, # PV Watts array type (0: Ground Mount Fixed (Open Rack); 1: Rooftop, Fixed; 2: Ground Mount 1-Axis Tracking; 3 : 1-Axis Backtracking; 4: Ground Mount, 2-Axis Tracking)
-    tilt::Real= array_type == 1 ? 10 : 20, # tilt = 10 deg for rooftop systems, 20 for ground-mount
+    tilt::Real = (array_type == 0 || array_type == 1) ? 20 : 0, # tilt = 20 for fixed rooftop arrays (1) or ground-mount (2) ; tilt = 0 for everything else (3 and 4)
     module_type::Int=0, # PV module type (0: Standard; 1: Premium; 2: Thin Film)
     losses::Real=0.14, # System losses
     azimuth::Real = latitude≥0 ? 180 : 0, # set azimuth to zero for southern hemisphere
@@ -102,7 +102,7 @@ mutable struct PV <: AbstractTech
         off_grid_flag::Bool = false,
         latitude::Real,
         array_type::Int=1, # PV Watts array type (0: Ground Mount Fixed (Open Rack); 1: Rooftop, Fixed; 2: Ground Mount 1-Axis Tracking; 3 : 1-Axis Backtracking; 4: Ground Mount, 2-Axis Tracking)
-        tilt::Real= array_type == 1 ? 10 : 20, # tilt = 10 deg for rooftop systems, 20 for ground-mount
+        tilt::Real = (array_type == 0 || array_type == 1) ? 20 : 0, # tilt = 20 for fixed rooftop arrays (1) or ground-mount (2) ; tilt = 0 for everything else (3 and 4)
         module_type::Int=0, # PV module type (0: Standard; 1: Premium; 2: Thin Film)
         losses::Real=0.14,
         azimuth::Real = latitude≥0 ? 180 : 0, # set azimuth to zero for southern hemisphere

diff --git a/src/sam/libssc.dylib b/src/sam/libssc.dylib
diff --git a/test/runtests.jl b/test/runtests.jl
@@ -13,7 +13,7 @@ Random.seed!(42)
 if "Xpress" in ARGS
     @testset "test_with_xpress" begin
         @test true  #skipping Xpress while import to HiGHS takes place
-        #include("test_with_xpress.jl")
+        # include("test_with_xpress.jl")
     end
 
 elseif "CPLEX" in ARGS
@@ -172,9 +172,15 @@ else  # run HiGHS tests
         post["PV"]["array_type"] = 1 
         scen = Scenario(post)
 
-        @test scen.pvs[1].tilt ≈ 10
+        @test scen.pvs[1].tilt ≈ 20 # Correct tilt value for array_type = 1
 
-        ## Scenario 3:Cape Town; array-type = 0 (ground)
+        ## Scenario 3: Palmdale, CA; array-type = 2 (axis-tracking)
+        post["PV"]["array_type"] = 2
+        scen = Scenario(post)
+
+        @test scen.pvs[1].tilt ≈ 0 # Correct tilt value for array_type = 2
+
+        ## Scenario 4: Cape Town; array-type = 0 (ground)
         post["Site"]["latitude"] = -33.974732
         post["Site"]["longitude"] = 19.130050
         post["PV"]["array_type"] = 0 
@@ -188,7 +194,11 @@ else  # run HiGHS tests
         post["PV"]["tilt"] = 17
         scen = Scenario(post)
         @test scen.pvs[1].tilt ≈ 17
-    end
+
+
+    end    
+
+
 
     @testset "AlternativeFlatLoads" begin
         input_data = JSON.parsefile("./scenarios/flatloads.json")