Solar Generation · DE/LU

Solar power in the German electricity system

Solar photovoltaics is one of the defining technologies of the German energy transition. Installed capacity has grown to the point where solar is among the largest generation technologies in the German system, and on sunny days it can cover a substantial share of national electricity demand around midday. The fleet is highly decentralized, ranging from millions of rooftop installations to utility-scale solar parks, with the largest projects now reaching several hundred megawatts.

Regionally, solar capacity is concentrated in the south and east of Germany. Bavaria and Baden-Württemberg host large shares of the installed base, while Brandenburg, Saxony-Anhalt, and Mecklenburg-Vorpommern have become the home of many of the largest ground-mounted solar parks. In terms of grid responsibility, generation is split across the four German transmission system operators: 50Hertz in the east, TenneT in a corridor from north to south, Amprion in the west, and TransnetBW in the southwest.

Official data on German solar feed-in is published by the TSOs on the joint platform Netztransparenz, by the Bundesnetzagentur on SMARD, and on the ENTSO-E Transparency Platform. The complete registry of German generation units is maintained in the Marktstammdatenregister.

Why solar generation forecasts for DE/LU are important

Solar feed-in is an important driver of the intraday shape of German power prices. The midday generation peak compresses prices, can push them negative, and creates the steep morning and evening ramps that batteries and flexible assets trade on. Solar forecast quality therefore matters across the short-term market, from the day-ahead auction to continuous intraday trading.

Accurate solar forecasts are equally critical on the volume side. Direct marketers of solar portfolios need them to nominate correctly and avoid balancing costs. Balancing group managers use them to keep imbalances small in a system where deviations are settled at increasingly volatile imbalance prices. Grid and portfolio analysts use them to anticipate tight or oversupplied system situations before they materialize in prices.

Telescope Energy provides aggregated solar generation forecasts for the DE/LU bidding zone for these use cases.

How our forecast works

Telescope Energy operates a collaborative forecasting platform. Our proprietary ensemble engine combines models developed by our research team with forecasts from independent expert forecasters. Each contributing model is continuously evaluated against realized feed-in, and the ensemble weights individual signals by their recent performance. The combined signal is designed to use complementary model strengths and reduce dependence on any single model.

The underlying models process high-resolution numerical weather predictions from multiple weather providers and learn the relationship between weather conditions and actual solar feed-in across the German fleet. Forecasts are updated frequently as new weather model runs become available, so recent cloud cover and irradiance information can be reflected in each update. Forecasts are delivered through the Telescope API for integration into existing trading and nomination workflows.

What drives German solar generation?

Solar irradiance is the dominant factor, and cloud cover is its most volatile component. Broken cloud fields, fog layers, and fast-moving fronts can shift national feed-in by many gigawatts within hours, and they are precisely the situations where weather models disagree most. Beyond clouds, panel temperature matters: high summer temperatures reduce module efficiency, so peak feed-in does not always coincide with peak irradiance. In winter, snow cover on modules can suppress generation across entire regions.

Structural factors shape the baseline. Seasonality and day length set the envelope of possible generation, while the continuous expansion of installed capacity means that the same weather situation produces more feed-in every year, a drift that forecasting models must track. The regional distribution of capacity determines how strongly weather in a specific area, for example cloud cover over Bavaria, moves the national total. Curtailment due to grid congestion or negative prices can additionally push realized feed-in below the meteorologically possible level.

Capturing this mix of fast weather dynamics and slow structural drift is what an ensemble of diverse, continuously benchmarked models is designed to do.

Forecast accuracy

Accuracy claims are easy to make and hard to verify, which is why Telescope Energy is built around transparency. We publish historical forecasts alongside realized solar feed-in, free of charge, so that every prospective customer can benchmark our DE/LU solar generation forecast against their current provider or internal models before committing to anything.

Our ensemble approach is designed for consistent accuracy across weather regimes, including the situations where forecasts matter most: unstable cloud conditions, snow events, and days where weather models diverge. Because the ensemble reweights contributing models based on ongoing performance, the forecast automatically keeps pace with the rapid expansion of the German solar fleet, without depending on any single model remaining state of the art.

Frequently asked questions

What does this forecast include?

The product provides quarter-hourly P10, P50, and P90 solar generation forecasts in MW from D+0 through D+7.

How often is the forecast updated?

The forecast runs in rolling mode so new model information can be incorporated throughout the day.

How is the forecast delivered?

Forecasts are delivered through the Telescope API for integration into trading, nomination, analytics, and asset-optimization workflows. Request a pilot to evaluate the product with your own benchmark and use case.