As more loadshedding looms, SA Astronomical Observatory looks to the sun to power telescopes

By Yasmine Jacobs Time of article published Feb 23, 2021

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The South African Astronomical Observatory (SAAO), best known for the Southern African Large Telescope (SALT), is looking to alleviate the site’s dependence on Eskom and aims to develop a supplementary power plant that relies on batteries and solar power.

In 2011, SAAO commenced with an investigation into the feasibility of using solar power to offset the cost of electricity.

Initially, the cost of installing solar power was prohibitive and not implemented because it required capital investment. At the time, this capital investment was required for the primary focus of collecting data for astronomy sciences.

NASA later became interested in placing a telescope on the site as part of their ATLAS (Asteroid Terrestrial-impact Last Alert System) project. This project focused on identifying and locating asteroids that could potentially hit Earth.

However, due to South Africa’s ongoing loadshedding, concerns were raised about the availability of electricity.

“The backup generators at the site were also upgraded which obviated the need for an independent power supply for NASA’s ATLAS telescope,” said Keith Browne, SALT Electronics Engineer. “It was then possible to redirect funds to install a 40kVA grid-tied system that would benefit the entire site.”

The installation provided 53 kWp and served as a supplementary power supply to the existing Eskom supply.

“The observatory site has a good solar resource as it has an altitude of 1,780m with low rainfall and a relatively cool climate, all of which contributed to excellent PV operations,” said Browne. “Post a year of operation and with ‘real-world’ data in hand, the SALT Board was convinced that a similar-sized system would work on the SALT stores roof.”

In late 2020, another 53 kWp system was installed on the SALT stores roof. This too provided power for the entire site.

“Although both installations have the same installed capacity, the first installation had 156 PV modules of 340 Wp each and the second installation was 128 PV modules of 415 Wp each,” said Menno Sulsters, Operations Manager at SEM Solutions. “This demonstrates the improved efficiency of the PV modules over just a year, going from a maximum of 340W coming out of one PV module to 415W coming out of the same size PV module. Both installations have the same Huawei 40 kW inverter installed and are connected to the same online monitoring portal. To put this in laymen’s terms, both of the installations are running exceptionally well and are continuing to show a positive return on investment as operations continue, despite load-shedding, and energy consumption costs decrease”.

Because SAAO are on the Ruralflex tariff structure from Eskom, the cost of electricity varies during the day and in the summer and winter season.

“Electricity use is highest in the winter when the tariffs are highest and solar power the lowest, so SAAO is currently considering wind power to compensate for the high winter electricity consumption by residences on-site for heating in winter,” says Browne.

“As the globe looks towards using renewable energy sources, it is very satisfying that the largest single optical telescope in the Southern Hemisphere is already on that path,” says Browne. “Mankind has always loved to look towards the stars, and in Sutherland, that star watching is powered by one.”


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