* upload completely sent off: 282 out of 282 bytes Since we're using the -v option, we get a detailed response: * Connected to localhost (::1) port 8080 (#0) We have installed the server locally on our computer, using the example from our earlier article. However, for some of the NSRDB data relative humidity is not a given parameter, and pvdeg calculates the values from the downloaded data as an internal processing step.Inside the SOAP envelope, we specify the country (Poland) and finish the command with the SOAP server URL. This function internally leverages _psm3(). This function uses (), which returns a Python dictionary of metadata and a Pandas dataframe of the timeseries weather data. As an example, we’ll fetch a TMY dataset for Phoenix, AZ at coordinates (33.4484, -112.0740). The NSRDB, one of many sources of weather data intended for PV modeling, is free and easy to access using pvlib. environ # get dedicated key for tutorial from servier except KeyError : NREL_API_KEY = 'DEMO_KEY' # OK for this demo, but better to get your own key Fetching TMYs from the NSRDB # NREL_API_KEY = None # <- please set your NREL API key here # note you must use "quotes" around your key, for example: # NREL_API_KEY = 'DEMO_KEY' # single or double both work fine # during the live tutorial, we've stored a dedicated key on our server if NREL_API_KEY is None : try : NREL_API_KEY = os. If you have an NREL API key please enter it in the next cell. There’s also free open source command-line tools like cURL and HTTPie, and a popular nagware/freemium GUI application called Postman. The most popular Python package to interact with web APIs is requests. In addition to just using your browser, you can also access web APIs programmatically. Try the URL below to get the PVWatts energy output for a fixed tilt site in Broomfield, CO. Look over the NREL web usage instructions for some examples, but interacting with a web API can be as easy as entering a URL into a browser. We won’t go into too much more detail here, but the most common web method is GET which is pretty self explanatory. An API could be as simple as a function signature or its published documentation, EG: the API for the solarposition function is you give it an ISO8601 formatted date with a timezone, the latitude, longitude, and elevation as numbers, and it returns the zenith and azimuth as numbers.Ī web API is the same, except the application is a web service, that you access at its URL using web methods. What exactly is an API? Nowadays, the phrase is used interchangeably with a “web API” but in general an API is just a recipe for how to interface with a application programmatically, IE: in code. Application Programming Interface (API) # Please pause now to visit and get an API key. Skip ahead to the next section to learn more. NREL has some API usage instructions, but pvlib has a few builtin functions, like _psm3(), that wrap the NREL API, and call them for you to make it much easier to use. You can test out the APIs using the DEMO_KEY but it has limited bandwidth compared to the usage limit for registered users. In order to use these resources from NREL, you need to register for a free API key. Each provider offers data under subscription that will provide access to irradiance (and other weather variables) via API to leverage in python.Īt the NREL Developer Network, there are APIs to a lot of valuable solar resources like weather data from the NSRDB, operational data from PVDAQ, or indicative calculations using PVWatts. Data is available at different spatial and time resolutions. There are several commercial providers of solar irradiance data. Where else can you get historical irradiance data? # You can get PVGIS TMY data using _pvgis_tmy(). PVGIS - Free global weather data provided by the European Union and derived from many govermental agencies including the NSRDB. It’s in its own format file (‘EPW’) so you can’t open it easily in a spreadsheet program like Excel, but you can use _epw() to get it into a dataframe and use it. An “API” is an “application programming interface”, and a “web API” is a programming interface that allows you to write code to interact with web services like the NSRDB.ĮPW - Energy Plus Weather data is available for many locations accross the world. You can access data through the website for many locations accross the world, or you can use their web API to download data programmatically. NSRDB - National Solar Radiation Database. For your projects, these are some of the most common: There are many different sources of solar irradiance data. Where to get Free Solar Irradiance Data? # Site meta-data containing (at least) Latitude, Longitude, Time Zone Weather data containing (at least) DNI, DHI, GHI, Temperature, RH, Wind-Speed The function has two minimum requirements: Import os import pvlib import pvdeg import pandas as pd from pvdeg import DATA_DIR import matplotlib.pyplot as plt 1.
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