What evidence should bidders provide when a PVWatts run…

Key Takeaways

• PVWatts V8 permits file_id in place of latitude/longitude, but the file_id must be a valid id returned by Solar Dataset Query V2.
• The Solar Dataset Query V2 evidence should include the request location, selected dataset key, returned id, station metadata, warnings, and any null dataset results.
• When file_id is used, PVWatts V8 says the dataset parameter should not be passed to specify the climate data file.
• The PVWatts station_info section is essential evidence because it reports the weather data source and climate file details used in the simulation.
• PVWatts outputs support a simulation record, but they do not prove product specifications, prices, certifications, savings, stock, or guaranteed performance.
• For international projects, use the dataset actually returned for the location; do not apply a United States dataset assumption to other countries.

Summary

When a bidder submits a PVWatts V8 run that uses a Solar Dataset Query file identifier instead of latitude and longitude, the evidence package should show how that file identifier was obtained, which climate dataset it came from, and how PVWatts confirmed the weather file used in the simulation. PVWatts V8 allows either latitude/longitude or a file_id; the file_id must be a valid identifier returned by the Solar Dataset Query V2 API, and it is required when lat/lon are not specified. [PVWatts V8; Solar Dataset Query V2]

1. Prove the file identifier came from Solar Dataset Query V2

Bidders should provide the Solar Dataset Query V2 request and response for the project location. The request should include format, api_key, lat, and lon, because Solar Dataset Query V2 requires latitude and longitude for the location lookup. [Solar Dataset Query V2]

The response evidence should include the selected dataset key and its id field, because Solar Dataset Query V2 returns climate data file information under dataset keys such as nsrdb, tmy2, tmy3, and intl. [Solar Dataset Query V2] If a bidder used file_id in PVWatts, the file_id should match the id returned by Solar Dataset Query V2 for the selected dataset. [PVWatts V8; Solar Dataset Query V2]

A useful bid appendix should also preserve the returned station metadata: latitude, longitude, city, state, timezone, elevation, distance, and weather_data_source where available, because these are output fields in Solar Dataset Query V2. [Solar Dataset Query V2] If a dataset is unavailable, bidders should disclose that as unknown or not available for that dataset, because the service can return null for a dataset and warnings when data is not found. [Solar Dataset Query V2]

2. Show that the PVWatts run used file_id correctly

PVWatts V8 states that lat and lon are required only if file_id is not specified, while file_id is required if lat/lon are not specified. [PVWatts V8] Therefore, a bidder using file_id should provide the PVWatts request parameters showing the file_id and the other required PVWatts inputs: format, api_key, system_capacity, module_type, losses, array_type, tilt, and azimuth. [PVWatts V8]

Bidders should not also use the dataset parameter as proof of the selected file when file_id is supplied. PVWatts V8 says dataset should not be passed when file_id is used to specify the climate data file. [PVWatts V8] If a bidder includes dataset in a file_id-based run, the bid should explain why and provide the actual PVWatts response warnings and errors rather than assuming the run is equivalent. PVWatts responses include errors and warnings fields. [PVWatts V8]

3. Keep the weather-source chain auditable

The bidder should include the PVWatts station_info section from the simulation response. PVWatts station_info reports the climate station latitude, longitude, elevation, timezone, location, city, state, solar_resource_file, distance, and weather_data_source. [PVWatts V8]

This matters because Solar Dataset Query identifies available climate data files for a location, while PVWatts reports the weather data used in the simulation. [Solar Dataset Query V2; PVWatts V8] A reviewer should be able to compare the Solar Dataset Query selected id and weather_data_source with the PVWatts station_info location, solar_resource_file, and weather_data_source. If those items do not align, the reason is unknown from the supplied documents and should be clarified by the bidder.

4. Separate model evidence from product claims

PVWatts V8 outputs can include monthly plane-of-array irradiance, monthly DC output, monthly AC output, annual AC output, monthly and annual solar radiation, and capacity factor. [PVWatts V8] If hourly output is requested, PVWatts can return hourly AC output, irradiance, DC output, ambient temperature, module temperature, windspeed, and albedo fields. [PVWatts V8]

Those outputs support a PVWatts simulation record, not broader product claims. The supplied API documents do not prove SOLARTODO product specifications, certification status, deployment history, stock availability, pricing, savings, or guaranteed performance. Any procurement recommendation should therefore be framed as a recommendation to request evidence, not as a confirmed claim.

5. Recommended bidder evidence checklist

Ask bidders to submit: the Solar Dataset Query V2 request URL parameters; the full Solar Dataset Query V2 response for the selected location; the selected dataset key and id; any warnings or null dataset results; the full PVWatts V8 request showing file_id instead of lat/lon; the full PVWatts V8 response; the PVWatts station_info section; and the PVWatts outputs used in the bid model. These items are recommended because the two supplied documents define how file identifiers are returned, how PVWatts accepts file_id, and how PVWatts reports the weather data and simulation outputs. [Solar Dataset Query V2; PVWatts V8]

If the bid is international, do not apply a United States-only data assumption. The Solar Dataset Query V2 documentation lists nsrdb, tmy2, tmy3, and intl dataset keys, and describes intl as PVWatts International station data. [Solar Dataset Query V2] The correct evidence is the dataset actually returned and used for the specific project location, not a default country assumption.

FAQ

What is the main evidence bidders should provide?

They should provide the Solar Dataset Query V2 response that returned the file id and the PVWatts V8 response that used that file_id.

Can PVWatts V8 use file_id instead of latitude and longitude?

Yes. PVWatts V8 states that file_id is required if lat/lon are not specified, and lat/lon are required if file_id is not specified.

Where should the file_id come from?

It should be a valid id returned by the Solar Dataset Query V2 API for the project location.

Should bidders include the dataset parameter when using file_id?

PVWatts V8 says dataset should not be passed when using file_id to specify the climate data file.

What station details should reviewers check?

Reviewers should check station_info fields such as location, solar_resource_file, weather_data_source, latitude, longitude, elevation, timezone, and distance.

What if Solar Dataset Query returns null for a dataset?

The bidder should disclose the null result and any warnings; the missing dataset should be treated as unavailable rather than inferred.

Do PVWatts outputs prove equipment performance guarantees?

No. The supplied documents describe simulation inputs and outputs; they do not prove equipment guarantees, certifications, price, stock, or actual deployed performance.

How should international projects be handled?

Use the dataset returned for the specific project location, including intl where applicable; do not assume a United States dataset applies outside the United States.

References

• PVWatts V8 API Documentation: Defines PVWatts V8 request parameters, file_id behavior, dataset guidance, station_info fields, outputs, examples, rate limits, and validation errors. — https://developer.nlr.gov/docs/solar/pvwatts/v8/
• Solar Dataset Query V2 API Documentation: Defines how to query available solar resource data by latitude and longitude, including returned dataset keys, climate file ids, station metadata, warnings, and supported datasets. — https://developer.nlr.gov/docs/solar/data-query/v2/