Reporting the performance of ZigZagSolar-facade after a full year: the Eisenhower-project

The company Creteq represents the ZigZagSolar-technology. We offer facade parts and engineering services to contractors and facade installers for building superb solar facades on international scale. ZigZagSolar offers inspiration and guidance to architects and project developers for buildings ranging from architectural landmark-buildings to retrofit-solutions for comfortable housing. ZigZagSolar offers a complete kit for anything you need to build an innovative solar facade: high-performance solar yield, best thermal insulation, aesthetic, freedom in design, affordable, reliable, compliant. We can include solar thermal and accessories.

In this report we describe our findings after one year of monitoring one of our projects: the Eisenhower project. A retrofitting-project for a housing association in the Netherlands.

Figure 1: shadow from neighbouring apartment block.

In the Eisenhower-street in Sittard our largest solar façade in the Netherlands was installed in 2017. We have closely monitored its performance. It generated more than 27 MWh of green energy in the first year. Our proprietary simulation tools predicted the performance accurately. It has been a challenge to predict the yield considering disturbances from trees, streetlights, adjacent buildings, albedo, geometrical considerations next to the the properties of the solar modules, inverters and electronics. On the East side of the ZigZagSolar-facade at a distance of about 50 metres there is an apartment block of equal height that casts a shadow on the facade in the morning. This shadow results in losses on the lower left corner of the facade, most in spring and autumn. This apartment block takes away a part of the diffuse light as well. We needed to make a special string design to accommodate for the shadow and for the effect of diffuse light. The chart below shows results of ‘shading analysis’ o f a ZigZagSolar unit. Furthermore there are still trees that cast a shadow in wintertime on the lower part of the facade. These trees do have an effect on the “perceived albedo”: and the diffuse light on different parts of the facade.

Figure 2: shadow has large influence on yield despite smart electronics

Clean electricity is in great need in wintertime for lighting, heating and electrical transportation. Our monitoring data from Eisenhower flat shows ZigZagSolar offers a very high yield during winter days and clearly outperforms rooftop solar panels and vertical facades. (Vertical solar facades miss out on large amount of diffuse light in winter.)
In combination with for instance heat pumps, LED lighting and other methods, ZigZagSolar can help apartment buildings reaching nearly-zero-energy. The picture below shows the performance of ZigZagSolar vs rooftop solar panels on a sunny winter day, equal amount of installed capacity.

Figure 3: ZigZagSolar outperforms rooftop clearly in winter.

The parts for the ZigZagSolar façade were largely pre-fabricated in the workshop and required minimal retrofitting of the wall. The whole project was finished within 21 days. This is very fast considering the innovative nature of the project. Fast installation saves unnecessary noise and disturbance to tenants.
There is no need to evacuate or disturb tenants while creating a superb energy-efficient building.
ZigZagSolar offers building managers clear on-line status information of every solar panel and inverter. It is easy to observe performance and to identify errors. The following picture is an example of ‘heat map’ showing cumulative electrical generation by different solar panels on a ZigZagSolar façade. This graph shows the importance of taking the influence of sources of shade and objects that influence the availability of diffuse light on the facade. We have repeated the simulations on vertical solar facades. Our simulations confirm experiences as reported in literature that vertical solar facades are very sensitive to disturbances in the surroundings. Sophisticated simulations are required for a good prediction of the electrical yield. ZigZagSolar can optimize the solar facade for any location, climate, orientation and surrounding and make a reliable prediction of the electrical yield.

Figure 4: Solar facades are challenging for solar engineers: shadow, albedo, diffuse light.

After the installation of this facade we have further improved the design of the ZigZagSolar-products. We can now offer a substantially higher yield at significantly lower cost thanks to the learnings from this project. We really thank ZOwonen, RVO, SEAC, LENS, GIPE, WAREBO and all supporting parties for their kind support. We can offer even better solutions for the European NZEB-directive. ZigZagSolar is currently expanding to hot climates as well. We have found in hot climates ZigZagSolar can offer tremendous additional savings in electricity bills for HVAC.

Every time you think about designing a facade; just give us a call. info@zigzagsolar.com

Wim van de Wall & Xin Xu

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