Utility Utility Scale Solar Forecasts

API documentation for the Utility Scale Solar Farm Forecasting product

Utility Scale Solar Forecasts via API

Solcast delivers Utility Scale solar forecasting data via an API framework that connects you to a global Rapid Update forecasting system.

You can read our docs here.

The easiest way to add a test site, build API requests or download data to CSV is using the Solcast API Toolkit.

Quick Start Example

Once you’ve registered for the Solcast API, you’re assigned a selection of test sites which will allow you to download forecast and recent estimated actuals data in a variety of formats.

Each Utility Scale site has a unique resource ID that links the user to stored information about the system’s installed capacity, location and tracking information. This resource ID allows you to retrieve the latest forecasting information and POST PV power measurements. Posting PV power measurements allows Solcast’s PV Tuning technologies to improve and individualise your forecasts.

GET solar farm forecasting data

With your unique resource ID, you can take a number of actions via a GET request:

  • Download the latest forecast data
  • View recent solar forecast performance
  • Retrieve recent estimated actuals
  • Display a demo chart of available data

The following sections include examples of these requests.

Download the latest forecasting data

The Nyngan solar farm (a 102MW solar farm in NSW Australia) has the unique resource ID . To retrieve its forecasting data in .csv format, the API GET request is:

GET https://api.solcast.com.au/utility_scale_sites/720f-098e-5591-0000/forecasts?format=csv

Or in JSON format:

GET https://api.solcast.com.au/utility_scale_sites/720f-098e-5591-0000/forecasts?format=json

Or to display in a web browswer:

GET https://api.solcast.com.au/utility_scale_sites/720f-098e-5591-0000/forecasts

Which displays the data in a user friendly format: nyngan-solar-farm-example.png

The user can also retrieve recent historical data by replacing forecasts to estimated_actuals in the URL string.

Display recent accuracy or live forecasting data

The user can also display one of two easy-access demo charts, by appending /recent or /accuracy to the URL.

The /recent demo chart can be called by entering the following URL in the browser (once authenticated):



And in the spirit of transparency, the /accuracy demo chart can be called via:


This chart displays the 1-hour ahead forecast agains the estimated actuals, and PV measurement data if live POST-ing is active (this is the case with Nyngan):


Accessing 5, 10 or 15 minute data

Solcast’s Rapid Update solar forecasting data is available at 5, 10, 15 and 30 minute resolutions. The default API GET request will retrieve 30 minute data (PT30M). The user can adjust the resolution of the forecast by appending ?period=PT[XX]M to the GET request, replacing [XX] with 5, 10 or 15.

For example, five-minute resolution forecasting data can be retrieved in JSON format for Nyngan by:

GET https://api.solcast.com.au/utility_scale_sites/5eb3-6d95-6557-ee25/?period=PT5M&format=json

Similarly, the recent demo chart can also have its resolution adjusted:


How to add your own site?

Under the Free plan, you can add one test site; paid customers can add as many as needed. The easiest way to add a test site, build API requests or download data to CSV is using the Solcast API Toolkit. Using the API, you can add your first site by initiating a POST request to the API. Here’s how:

To create your Utility Scale Site, the user will have to complete a POST request in the following JSON format (with >YOUR_KEY< replaced by your API Key):

POST https://api.solcast.com.au/utility_scale_sites?format=json&api_key=>YOUR_KEY<

With the JSON variables as follows:

Property Name Description Required
name A friendly display name for a site Y
capacity The capacity of utility site which represents the sum total of inverter capacity of AC capacity. Units in megawatts (MW). Y
capacity_dc The capacity of the solar modules at the utility scale site or DC capacity. Units in megawatts (MW) N
tracking_type This represents if the site is a fixed tilt PV site or has horizontal tracking. Defaults to ‘fixed’ but can be specified as ‘horizontal_single_axis’ or ‘fixed’ N
longitude Longitude of the PV system (WGS84) Y
latitude Latitude of the PV system (WGS84) Y
install_date Date of installation of the PV site N
tags An array of strings associated to the site N
azimuth Azimuth of the PV system (180 to -180) where 0 is North, -90 is East and 90 is West N
tilt Tilt of the PV system (between 0-90) where 0 is flat. This is ignored if ‘tracking_type’ is anything other than ‘fixed’ N
inverter_efficiency The efficiency of the inverters at the site as a value between 0 and 1 where 1 is 100% efficient N
loss_factor A value between 0-1 that represents the efficiency of system where 1 is 100% efficient N

An example of a correctly formatted POST request is also provided here:


Once successful, the user should receive a response, which will issue you your unique resource ID:

Property name Description
site Same as request but with the inclusion of the generated ‘resource_id’
resource_id The unique ID for the newly created site. This is to be used in any subsequent requests for this specific site. eg ‘1234-abcd-1234-abcd’

Additional Information

You can find more helpful information about setting up a Utility Scale solar forecasting site in our “Getting Started” series on Intercom.