Improving the solar production forecast

Leading energy companies are investing in large solar power plants worldwide. Even private households are more and more setting up their own solar panels, adjusting to the ecological mindfulness society, which comes with economical benefits. The need of accurately predicted power production is critical for organizing how, where and when, to use the produced solar power energy in the most efficient and economical way. This is where the BCDC Energy weather forecast project has an important role, to prepare new standards on the ability to utilize the energy resources in best way in future.

The solar energy forecast tells one how much energy there can be available for the next hours or next days. Why does the solar power production forecast sometimes go wrong and what can be done to make them better? Clouds, among all weather parameters, have the largest impact on surface level solar radiation. Therefore, it is not surprising that solar power production forecasts are highly sensitive to cloud forecasts. Earlier results show that the forecasted cloudiness is underestimated, to some extent, which results in over-prediction of solar radiation. How can we make the models forecast better in this aspect?

Spotting cloud placement, timing and properties

Numerical Weather Prediction (NWP) models are highly capable of predicting several meteorological parameters. In this study we focus on the cloudiness and the related solar radiation. In general the clouds and radiation are forecasted well, when compared with observations. Still there are and will be uncertainties in the forecasts. This especially relates to what kind of weather situations being predicted. For example during a warm summer day the Cumulus “warm air-bubbles”-clouds (which later can grow into a rain-shower; Cumulonimbus), is something that the forecast model does predict, but the accurate placement and timing of such clouds are challenging. Often these clouds are in the right regional area but with a displacement of few kilometers and this can, naturally, have a critical effect on the solar power production in a specific point location.

Frontal situations, with their large-scale broad and deep cloud-structures, are generally easier to predict in a forecast model. One key factor, determining the solar power energy, is the thickness of clouds. A very high and “light” Cirrus cloud can easily be penetrated by the sun-rays and give almost full radiation at that time, whereas a thick rain-shower cloud (Cumulonimbus) would barely leave any sun-radiation reaching the ground.

A new solution

The aim of our project work is to improve the predictability of the cloud placement, timing and properties (e.g. thickness and opacity) and thereby the quality of the radiation output, when it comes to small scales in both time (hours) and the areal coverage (kilometers). The current work involves starting the weather model from a more accurate initial state, i.e. where the clouds have better placement and vertical extension, from the beginning of model start. With this technique the forecast model has the potential to better predict the cloudiness for the next hours and day-ahead.

We use satellite data and surface observations of clouds, in order to describe the cloud field at the starting point of the model run. The satellite gives the advantage of seeing the clouds from above and it does so with high accuracy (see figure 1). However, satellites do not “see” what is beneath the first cloud-top, which is a limitation and the reason to include surface observations. Several meteorological surface stations are able to measure the height of the cloud-base. By combining this information with satellite data (such as the cloud-top temperature; figure 1, right panel) we get an estimate of the vertical extent of the cloud-structure. This is not a trivial task though.

Figure 1. Left panel: Satellite image of the clouds 22 July 2016, 12 UTC. Light blue-white color indicate high clouds (Cirrus) and yellow color show low-middle high clouds (Cumulus, Stratus and Alto Stratus). Right panel: Interpreted cloud-top temperatures derived from the satellite image, which are used as input for the forecast model to detect cloud-tops. Low clouds have higher temperatures compared to clouds at high altitudes (see temperature bar on right side, degree Celsius). 

Results have shown that the weather prediction model over-predicts the solar radiation in the first hours of the forecasts (see figure 2, left panel), because of either a displacement of the cloud field or too transparent clouds. The new approach of starting the forecast model with a more accurate cloud field is investigated in model experiment, where we run the weather forecast model for one month (July 2016) over Scandinavia domain and produce forecast out to +48 hours (i.e. 2 days) twice a day. The first results from our new experiment show that we are able to improve the cloud-free situations, i.e. the high radiation values (~700 W/m2) are lowered and are now at the same level as the observations (see Fig. 1). On the other hand, it is also seen that we underestimate the solar radiation in cloudy situations (see figure 2, right panel).

As of now, we investigate how to further optimize our new model. One working hypothesis is to optimize the vertical extent of the clouds. As mentioned before, the thickness of the cloud affects to the opacity (penetration of sun radiation). Our first verification results indicate that we get too thick and opaque clouds. Especially the high Cirrus-clouds, which are usually thin with high opacity, are modeled with too thick vertical extension zone. Finding out these problems helps us on how to further adjust the cloud assimilation methodology in the weather model and to improve the cloudiness and radiation output for the upcoming 1-2 days forecast. This is for the benefit of companies and households when planning their solar-power energy resources, in a more efficient and economically secure way.

Figure 2. Left panel: Reference forecast model (red) compared with observations (blue). Right panel: New forecast model version (red) vs. observations (blue). The dark red color refers to overlapping columns.


Erik Gregow

Erik Gregow is a doctoral researcher/ student in BCDC Weather teamFinnish Meteorological Institute. FMI is one of research institutes in BCDC Energy project.


Last updated: 13.3.2017


I have bookmarked your website because this site contains valuable information in it. I am really happy with articles quality and presentation. Thanks a lot for keeping great stuff. I am very much thankful for this site. Ostatus Gaming Fourm drugstore online shopping drugs for sale deep web drugstore online canadian pharmacy online 24 northwest pharmacies in canada

This is my first time i visit here. I found so many entertaining stuff in your blog, especially its discussion. From the tons of comments on your articles, I guess I am not the only one having all the leisure here! Keep up the good work. I have been meaning to write something like this on my website and you have given me an idea. Yu Gi Oh Duel Links Hack drugstore online shopping online drug store northwest pharmacy canada canadian pharmacy king best canadian pharmacy pharmacy near me canadian medications online [url=][/url] canadian pharmacies stendra global pharmacy canada canada online pharmacies for men canadian pharmacycanadian pharmacy prescription drugs without prior prescription [url=][/url] global pharmacy canada best canadian pharmacy cialis canadian pharmacy canadian pharmacies shipping to usa canadian prescription drugstore [url=][/url] online canadian pharmacies canadianpharmacyusa24h drugs for sale usa canada medications buy canadian pharmacy no prescription [url=][/url] canada medication prices candida viagra canadian medications list

Surely, it requires accurate placement and such clouds are challenging.

Hello! For the Solar Forecast Improvement Project (SFIP), the Earth System Research Laboratory (ESRL) is partnering with the National Center for Atmospheric Research (NCAR) and IBM to develop greater accurate strategies for sun forecasts using their modern day climate fashions. If anyone looking for Recruitment Services. Visit Here

Thanks For sharing this blog.

We are offer the best Home Furnishing in Noida, dealer and manufacturers, modular kitchen interior designer provider services in Ghaiziyabad, Faidabad, Greater Noida and entire places in Delhi. We have professional and expert team will give your kitchen's a modern and attractive look. For more details call us: 9868333789

We are providing the best Interior Designer in Delhi. We are artists, we are designers, and we are here to make your space better than you could have ever imagined. For more details call us: 7011210410 or visit my profile

We are providing the best services of website Designer in Delhi. We build sites to perform with a focus on strategic planning, compelling visual design, and flawless user experience, in order to drive superior results. For more details call: 9015664619

We are offer the best service Wedding planner in Ghaziabad. We are the budget arrange destination weddings in India. For more details call: 8287954880

Itconcept is one of the leading Computer repair service in Ghaziabad. We provide all kinds of computer/laptop repair services to all the people living and working in Ghaziabad. . For more details call: 9205059199

We are providing the best Color Printer on Hire in Delhi relies very less on distributing the actual pieces of paper this is because photocopiers continue to be widely used and almost everywhere. For more Details call: 9999924096

We are providing the best Skin Specialist in Noida. Dermanext Skin & Hair Clinic is a boutique clinic specialising in dermatology, trichology and aesthetics. For more details call: 8860523726

We are offer Apply for Duplicate Pan Card in Delhi. If you are not holding a PAN card number or never applied before for PAN Card of individual. For more Details call: 9910266139

The best Repair laptop at home. Also, our services are affordable and all the repairing work is performed by expert technicians. Get your computer repaired today. For more details call : 9868243838

The best Tattoo Shop in Delhi. A tattoo is a lifelong investment, and we at The Ink Boy Tattoo Studio understand that. In order to provide our customers with the best tattooing experience we devote time to designing and customizing tattoos according to our client’s needs. For more details call: 8745801112

It’s very easy to find out any matter on web as compared to textbooks, as I found this piece of writing on this site. Thanks a lot for giving everyone an extremely breathtaking chance to read from this blog.

Awesome and interesting post. Great things you've always shared with us. Thanks a lot. Keep posting its kind of information.

Discover your content it's really good. I really appreciate your efforts in writing such an insightful piece of content. Glad that you sharing this with us.

Add new comment