---
title: "Long-Term Averages API subscription details"
slug: "lta-subscription-details"
updated: 2026-03-26T08:36:05Z
published: 2026-03-26T08:36:05Z
canonical: "kb.solargis.com/lta-subscription-details"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://kb.solargis.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Long-Term Averages API subscription details

**In this document**

You will learn what services, data types, and features are included in Solargis Long-Term Averages (LTA) API subscription.

## Long-Term Averages API data parameter specifications

| Parameter | Aggregation | API parameter | Unit | Source | Spatial resolution |
| --- | --- | --- | --- | --- | --- |
| Global Horizontal Irradiation | Daily sums | GHD | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Monthly sums | GHM |
| Direct Normal Irradiation | Daily sums | DNID | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Monthly sums | DNIM |
| Diffuse Horizontal Irradiation | Daily sums | DHD | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Global Tilted Irradiation | Daily sums | GID | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Monthly sums | GIM |
| Ground surface albedo | Monthly average | ALB | - | MODIS, ERA5, Solargis | 0.0083° (~1 km) |
| Diffuse irradiation | Daily sums | DID | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Reflected irradiation | Daily sums | RID | kWh/m2 | Solargis | 0.00083° (~90 m) |
| Interannual variability of GHI | Monthly average | INVAR | % | Solargis | 0.00083° (~90 m) |
| Losses to GHI due to terrain shading | Monthly average | SHLOSS | % | Solargis | 0.00083° (~90 m) |
| Air temperature at 2 m | Monthly average | TD | °C | ERA5-Land/Solargis | 0.0083° (~1 km) |
| Monthly minimum | TMIN |
| Monthly maximum | TMAX |
| Wind speed at 10 m | Monthly average | WS | m/s | ERA5 | 0.25° (~28 km) |
| Relative humidity | Monthly average | RH | % | ERA5 | 0.25° (~28 km) |
| Precipitable water | Monthly average | PWAT | kg/m² | ERA5 | 0.25° (~28 km) |
| Precipitation | Monthly sum | PREC | mm | ERA5-Land, ERA5, Solargis | 0.1° (~11 km) |
| PVOUT (specific and total) | Daily sums | ESD | kWh/kWp | Solargis | n/a |
| Monthly sums | ESM |
| Monthly sums | ETM | MWh |
| PVOUT monthly proportion | Monthly proportion of the yearly sum | ESHARE | % | Solargis | n/a |
| Performance Ratio | Monthly average | PR | % | Solargis | n/a |

Note that all data is provided as average monthly values over the relevant time frame (see Reference periods for LTA data). Yearly sums or averages are provided with the monthly values of all parameters except the minimum and maximum air temperature.

In addition to the parameters listed in the table above, the following losses in the power conversion chain are quantified in absolute and relative terms:

- Terrain shading losses
- Angular reflectivity losses
- Losses in the conversion of solar radiation to DC power in the PV modules
- DC system losses
- Inverter losses (clipping and efficiency)
- AC system losses
- Unavailability losses

The performance ratio of the partial power conversion chain before and after the respective loss is also quantified.

## LTA API subscriptions - technical details

| Reference periods for LTA data | **Solar parameters**: 1994/1999/2005/2007/2018/2019 – end of 2024 (Figure 1) **Meteorological parameters**: 1994 – 2024 **Albedo**: 2006 – 2015 |
| --- | --- |

![](https://cdn.document360.io/ae2d502f-6c0d-4865-a68e-43ad8da61149/Images/Documentation/image-0AF3TWA0.png) ***Figure 1:****Geographical coverage of Solargis Long-Term Averages data*