PVWatts (Version 4) (GET /api/pvwatts/v4)

NREL's PVWatts calculates the energy production of grid-connected photovoltaic (PV) energy systems. This service estimates the performance of hypothetical residential and small commercial PV installations.

PVWatts Version 4 has been replaced by version 5. While we will continue to make the V4 API available, it is recommended that people switch to version 5 to use the most up-to-date models available.

Request URL

GET /api/pvwatts/v4.format?parameters

Request Parameters

Parameter Required Value Description

format

Yes

Type: string

Default: None

Options: json, xml

The output response format.

api_key

Yes

Type: string

Default: None

Your developer API key. See API keys for more information.

system_size

Yes

Type: decimal

Default: None

Range: 0.05 to 500000

Nameplate capacity (kW).

address

Depends

Type: string

Default: None

The address to use (lat/lon returned by Google's geocoding service). Required if lat/lon or file_id not specified.

lat

Depends

Type: decimal

Default: None

Range: -90 to 90

The latitude for the location to use. Required if address or file_id not specified.

lon

Depends

Type: decimal

Default: None

Range: -180 to 180

The longitude for the location to use. Required if address or file_id not specified.

file_id

Depends

Type: string

Default: none

Reference to a specific climate data file to use. Must be a valid id returned by the Solar Dataset Query API. Required if lat/lon or address not specified.

dataset

Type: string

Default: tmy3

Options: tmy2, tmy3, intl, IN

The climate dataset to use. Should not be passed in if using file_id to specify the climate data file.

Option	Description
tmy2	TMY2 station data (see Typical Meteorological Year, version 2)
tmy3	TMY3 station data (see Typical Meteorological Year version 3)
intl	International station data
IN	India 10km gridded solar resource data (see India Solar Resource Maps)

radius

Type: integer

Default: 100

The search radius to use when searching for the closest climate data station (miles). Pass in radius=0 to use the closest station regardless of the distance.

timeframe

Type: string

Default: monthly

Options: monthly, hourly

Granularity of the output response.

azimuth

Type: decimal

Default: None

Min: 0

Max: < 360

Azimuth angle (degrees).

derate

Type: decimal

Default: None

Range: 0 to 1

System derate value.

tilt

Type: decimal

Default: None

Tilt angle (degrees).

tilt_eq_lat

Type: integer

Default: 0

Options: 0, 1

Override the tilt variable to equal latitude (default 0 unless tilt provided).

Option	Description
0	False
1	True

track_mode

Type: integer

Default: 1

Options: 0, 1, 2

Tracking mode.

Option	Description
0	Fixed
1	1-Axis
2	2-Axis

inoct

Type: decimal

Default: None

Range: 30 to 80

Nominal operating cell temperature (C)

gamma

Type: decimal

Default: None

Range: -2 to -0.01

Max power temperature coefficient (%/C)

callback

Type: string

Default: None

Return the data using JSONP and the given callback function (only applicable when using the json format).

Response Fields

The response is composed of service-related informational fields and the results of the PVWatts simulation.

Field	Value	Description
inputs	Type: collection	The input parameters received in the request.
errors	Type: array of strings	Any error messages resulting from the request.
warnings	Type: array of strings	Any warning messages resulting from the request.
version	Type: string	The current version of the web service.
ssc_info	Type: collection	Information about the SSC library.
station_info	Type: collection	Information about the climate data used in the simulation. (see station info fields for more detail)
outputs	Type: collection	The data outputs from the simulation. (see output fields for more detail)

Station Info Fields

Field	Value	Description
lat	Type: decimal	Latitude of the climate station.
lon	Type: decimal	Longitude of the climate station.
elev	Type: decimal	Elevation of the climate station. (meters)
tz	Type: decimal	Timezone offset from GMT.
location	Type: string	ID of the climate station.
city	Type: string	City where climate station is located.
state	Type: string	State where climate station is located.
file_name	Type: string	Solar resource filename.
distance	Type: integer	Distance between the input location and the climate station. (meters)

Output Fields

Field	Value	Description
poa_monthly	Type: array of decimal	Monthly plane of array irradiance values. The array of values represents the value for each month, with the first element being for January and the last element being for December.
dc_monthly	Type: array of decimal	Monthly DC array output. The array of values represents the value for each month, with the first element being for January and the last element being for December.
ac_monthly	Type: array of decimal	Monthly AC system output. The array of values represents the value for each month, with the first element being for January and the last element being for December.
ac_annual	Type: decimal	Annual AC system output.
solrad_monthly	Type: array of decimal	Monthly solar radiation values. The array of values represents the value for each month, with the first element being for January and the last element being for December.
solrad_annual	Type: decimal	Annual solar radiation values.
ac	Type: array of decimal	Hourly AC system output (only when timeframe=hourly)
poa	Type: array of decimal	Hourly plane of array irradiance (only when timeframe=hourly)
dn	Type: array of decimal	Hourly beam normal irradiance (only when timeframe=hourly)
dc	Type: array of decimal	Hourly DC array output (only when timeframe=hourly)
df	Type: array of decimal	Hourly diffuse irradiance (only when timeframe=hourly)
tamb	Type: array of decimal	Hourly ambient temperature (only when timeframe=hourly)
tcell	Type: array of decimal	Hourly module temperature (only when timeframe=hourly)
wspd	Type: array of decimal	Hourly windspeed (only when timeframe=hourly)

Examples

JSON Output Format

GET /api/pvwatts/v4.json?api_key=DEMO_KEY&system_size=4&dataset=tmy2&derate=0.77&lat=40&lon=-105

{
  "station_info": {
    "tz": -7,
    "location": "94018",
    "lon": -105.25,
    "file_name": "94018.tm2",
    "city": "BOULDER",
    "state": "CO",
    "lat": 40.01666641235352,
    "elev": 1634,
    "distance": 21235
  },
  "errors": [

  ],
  "version": "4.0.0",
  "inputs": {
    "system_size": "4",
    "lon": "-105",
    "derate": "0.77",
    "dataset": "tmy2",
    "lat": "40",
    "api_key": "DEMO_KEY"
  },
  "warnings": [

  ],
  "outputs": {
    "poa_monthly": [
      137.1923980712891,
      137.0316772460938,
      187.4732360839844,
      182.7943878173828,
      185.7599792480469,
      182.4970855712891,
      187.8779907226562,
      193.34228515625,
      187.3993988037109,
      175.8596649169922,
      137.8765869140625,
      132.9652557373047
    ],
    "dc_monthly": [
      468.0147399902344,
      457.9238891601562,
      616.0709228515625,
      581.62548828125,
      576.5953979492188,
      551.68603515625,
      553.3501586914062,
      569.5568237304688,
      564.85595703125,
      550.3904418945312,
      460.4128112792969,
      454.1395263671875
    ],
    "ac_annual": 5834.35107421875,
    "solrad_annual": 5.553147792816162,
    "ac_monthly": [
      426.7577514648438,
      417.6890869140625,
      563.779541015625,
      529.3705444335938,
      523.4755249023438,
      500.5887451171875,
      502.0051879882812,
      518.2822875976562,
      515.994140625,
      503.0267639160156,
      420.1042785644531,
      413.2771606445312
    ],
    "solrad_monthly": [
      4.425561428070068,
      4.893988609313965,
      6.047523975372314,
      6.093146324157715,
      5.992257595062256,
      6.083236217498779,
      6.060580253601074,
      6.236847877502441,
      6.246646404266357,
      5.672892570495605,
      4.59588623046875,
      4.289201736450195
    ]
  },
  "ssc_info": {
    "version": 27,
    "build": "Unix 64 bit GNU/C++ Jan 10 2013 20:00:07"
  }
}

XML Output Format

GET /api/pvwatts/v4.xml?api_key=DEMO_KEY&system_size=4&dataset=tmy2&derate=0.77&lat=40&lon=-105

<?xml version="1.0" encoding="UTF-8"?>
<response>
  <inputs>
    <api-key>DEMO_KEY</api-key>
    <system-size>4</system-size>
    <dataset>tmy2</dataset>
    <derate>0.77</derate>
    <lat>40</lat>
    <lon>-105</lon>
  </inputs>
  <errors type="array"/>
  <warnings type="array"/>
  <version>4.0.0</version>
  <ssc-info>
    <version type="integer">27</version>
    <build>Unix 64 bit GNU/C++ Jan 10 2013 20:00:07</build>
  </ssc-info>
  <station-info>
    <lat type="float">40.016666412353516</lat>
    <lon type="float">-105.25</lon>
    <elev type="float">1634.0</elev>
    <tz type="float">-7.0</tz>
    <location>94018</location>
    <city>BOULDER</city>
    <state>CO</state>
    <file-name>94018.tm2</file-name>
    <distance type="integer">21235</distance>
  </station-info>
  <outputs>
    <ac-monthly type="array">
      <ac-monthly type="float">426.75775146484375</ac-monthly>
      <ac-monthly type="float">417.6890869140625</ac-monthly>
      <ac-monthly type="float">563.779541015625</ac-monthly>
      <ac-monthly type="float">529.3705444335938</ac-monthly>
      <ac-monthly type="float">523.4755249023438</ac-monthly>
      <ac-monthly type="float">500.5887451171875</ac-monthly>
      <ac-monthly type="float">502.00518798828125</ac-monthly>
      <ac-monthly type="float">518.2822875976562</ac-monthly>
      <ac-monthly type="float">515.994140625</ac-monthly>
      <ac-monthly type="float">503.0267639160156</ac-monthly>
      <ac-monthly type="float">420.1042785644531</ac-monthly>
      <ac-monthly type="float">413.27716064453125</ac-monthly>
    </ac-monthly>
    <poa-monthly type="array">
      <poa-monthly type="float">137.19239807128906</poa-monthly>
      <poa-monthly type="float">137.03167724609375</poa-monthly>
      <poa-monthly type="float">187.47323608398438</poa-monthly>
      <poa-monthly type="float">182.7943878173828</poa-monthly>
      <poa-monthly type="float">185.75997924804688</poa-monthly>
      <poa-monthly type="float">182.49708557128906</poa-monthly>
      <poa-monthly type="float">187.87799072265625</poa-monthly>
      <poa-monthly type="float">193.34228515625</poa-monthly>
      <poa-monthly type="float">187.39939880371094</poa-monthly>
      <poa-monthly type="float">175.8596649169922</poa-monthly>
      <poa-monthly type="float">137.8765869140625</poa-monthly>
      <poa-monthly type="float">132.9652557373047</poa-monthly>
    </poa-monthly>
    <solrad-monthly type="array">
      <solrad-monthly type="float">4.425561428070068</solrad-monthly>
      <solrad-monthly type="float">4.893988609313965</solrad-monthly>
      <solrad-monthly type="float">6.0475239753723145</solrad-monthly>
      <solrad-monthly type="float">6.093146324157715</solrad-monthly>
      <solrad-monthly type="float">5.992257595062256</solrad-monthly>
      <solrad-monthly type="float">6.083236217498779</solrad-monthly>
      <solrad-monthly type="float">6.060580253601074</solrad-monthly>
      <solrad-monthly type="float">6.236847877502441</solrad-monthly>
      <solrad-monthly type="float">6.246646404266357</solrad-monthly>
      <solrad-monthly type="float">5.6728925704956055</solrad-monthly>
      <solrad-monthly type="float">4.59588623046875</solrad-monthly>
      <solrad-monthly type="float">4.289201736450195</solrad-monthly>
    </solrad-monthly>
    <dc-monthly type="array">
      <dc-monthly type="float">468.0147399902344</dc-monthly>
      <dc-monthly type="float">457.92388916015625</dc-monthly>
      <dc-monthly type="float">616.0709228515625</dc-monthly>
      <dc-monthly type="float">581.62548828125</dc-monthly>
      <dc-monthly type="float">576.5953979492188</dc-monthly>
      <dc-monthly type="float">551.68603515625</dc-monthly>
      <dc-monthly type="float">553.3501586914062</dc-monthly>
      <dc-monthly type="float">569.5568237304688</dc-monthly>
      <dc-monthly type="float">564.85595703125</dc-monthly>
      <dc-monthly type="float">550.3904418945312</dc-monthly>
      <dc-monthly type="float">460.4128112792969</dc-monthly>
      <dc-monthly type="float">454.1395263671875</dc-monthly>
    </dc-monthly>
    <ac-annual type="float">5834.35107421875</ac-annual>
    <solrad-annual type="float">5.553147792816162</solrad-annual>
  </outputs>
</response>

Rate Limits

Standard rate limits apply. No more than 1,000 requests may be made in any hour

Errors

Standard errors may be returned. In addition, the following service-specific errors may be returned:

HTTP Status Code	Description
422	Unprocessable Entity - One or more parameters did not pass validation, or a parameter may be missing. Check the errors section of the response to see how the request should be modified to address the error.

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