Add an example for downloading and processing a URDB rate (#117)

Author: brtietz

Examples/UtilityRatesExample.py

@@ -0,0 +1,76 @@
+"""
+This example script shows how to set up the utility rate module using a rate downloaded from the Utility Rate
+
+This example requires an NREL developer key, which can be obtained from https://developer.nrel.gov/signup/
+
+Additional financial models, inputs, and outputs can be found at:
+* PV: https://nrel-pysam.readthedocs.io/en/master/modules/Utilityrate5.html
+
+Most recently tested against PySAM 3.0.1
+Requires: nrel-pysam, requests
+
+@author: brtietz
+"""
+import json
+import os
+import requests
+
+import PySAM.Utilityrate5 as utility_rate
+import PySAM.ResourceTools
+
+# Get a key from https://developer.nrel.gov/signup/
+key = "<YOUR_API_KEY>"
+
+# Download rate from URDB and save as file. If rate has already been downloaded, use file
+def get_urdb_rate_data(page, key):
+
+    # Full API can be viewed at: https://openei.org/services/doc/rest/util_rates/?version=8
+    urdb_url = 'https://api.openei.org/utility_rates?format=json&detail=full&version=8'
+    get_url = urdb_url + '&api_key={api_key}&getpage={page_id}'.format(api_key=key, page_id=page)
+
+    filename = "urdb_rate_{}.json".format(page)
+    print(filename)
+
+    if not os.path.isfile(filename):
+        print(get_url)
+        resp = requests.get(get_url, verify=False)
+        data = resp.text
+        # Cache rate as file
+        with open(filename, 'w') as f:
+            f.write(json.dumps(data, sort_keys=True, indent=2, separators=(',', ': ')))
+    else:
+        with open(filename, 'r') as f:
+            data = json.load(f)
+
+    return data
+
+if __name__ == "__main__":
+    path = os.getcwd() + os.path.sep
+    page = "618940545457a35a1c4097ec"  # https://apps.openei.org/USURDB/rate/view/618940545457a35a1c4097ec (DG-R Primary (Above 500kW))
+    urdb_response = get_urdb_rate_data(page, key)
+    urdb_response_json = json.loads(urdb_response)["items"][0]
+    rates = PySAM.ResourceTools.URDBv7_to_ElectricityRates(urdb_response_json) # To see status of version discrepancy, see https://github.com/NREL/pysam/issues/116. There's no difference between V7 and V8 for 99.9% of rates
+
+    ur = utility_rate.new()
+    for k, v in rates.items():
+        ur.value(k, v)
+
+    # Set up other defaults
+    analysis_period = 1 # Number of years to run the simulation
+    ur.value("analysis_period", analysis_period) 
+    ur.value("system_use_lifetime_output", 0) # Set to 1 if load and gen have length 8760 * analysis_period
+    ur.value("inflation_rate", 2.5) # Units of %
+    ur.value("degradation", [0] * analysis_period) # AC energy loss per year due to degradation during analysis period (%)
+
+    gen = [0] * 8760 # No renewable generation, run a technology compute module such as PVWatts8 to get this
+    load = [100] * 8760 # Constant 100 kW load - this could also be an array imported from CSV
+
+    ur.value("gen", gen) # Hourly kW
+    ur.value("load", load) # Hourly kW
+
+    ur.execute() # Run the utility rate module
+
+    print("Total utility bill without system ($): ", ur.Outputs.elec_cost_without_system_year1) 
+    print("Average $/kW", ur.Outputs.elec_cost_without_system_year1 / sum(load))
+
+