Great Western Coffee Shop

World's first solar-powered train line is turned on in Hampshire with 100 panels providing energy for lights and signalling systems

A solar farm of more than 100 panels in Hampshire has been plugged into a stretch of track in Hampshire in a world first. 

The stretch of track near Aldershot was today receiving 30kW from a nearby solar farm.

The renewable electricity will be used to provide energy for the signalling and lights on Network Rail's Wessex route.

It is hoped it can be the first step in establishing the necessary infrastructure for trains that are directly powered by solar energy.

The Byron Bay Railroad Company has now carried over 100,000 passengers between North Beach and Byron Beach. Trains run hourly from 10.00 to 17.00, taking about 10 minutes for the 3km trip; speeds are similar to those achieved on a British heritage railway. The route is mostly very straight and very flat.

The company describes its operations as 'carbon positive'. Solar panels on their operational buildings produce up to 30kW, and those on the roof of the train can provide an additional 6.5kW; there is a significant energy surplus. The train also recovers about 25% of its energy through regenerative braking. The 77kWh traction battery holds sufficient energy for 12-15 runs without recharging.

The service is provided by a single two-car NSW class 600/700 unit, consisting of railmotor 661 and trailer 726.  One of the Cummins NT855-R2 diesel engines has been removed from 661 to make space for the battery; the other is retained as a backup.

These units may be particularly suitable for this mode of operation: they were built at Chullora Workshops (which had expertise in aircraft fabrication having built Bristol Beaufort bombers during the war) and consist of an aluminium body bolted to a lightweight steel frame.

Could this technology, or a version of it, be used in Britain?

There is the rather obvious problem of "temporal mismatch" - morning and evening peaks for traction demand are not during daylight hours all year, and as for lighting demand in general... So to be useful it needs a big battery to store the energy until needed ... in which case the "direct from sunbeam to rail" factor has been diluted and the infeed might as well not go to the railway at all. Which is true in any case; while local infeed sounds better (for a start it's potentially more efficient), it does cause problems of control and security of supply which are likely to outweigh that. But hey, it's an experiment, let's (or let them) just see how it goes.

Alex Byford is head of delivery at Riding Sunbeams with long experience of power projects. He explains that the Aldershot installation is quite small, at 37kW, but enables the company “to prove to Network Rail’s product assurance and safety teams that renewables could be integrated without causing any issues with the rail network.” A data logger at the site is gathering information about power quality, in particular, to ensure that the equipment will neither cause problems nor itself be damaged as a result of being connected to “quite a dirty supply” that has issues with harmonics, reactive power and voltage fluctuations.
...
The Valley Lines will be electrified with overhead power lines running on 25kV AC, but - significantly - the supply will be single-phase, unlike the national transmission and distribution networks, which are three-phase.

Byford explains why this matters: “Single-phase electricity is normally used in domestic installations at 240V, whereas this is at 25kV, so the issue is that no equipment has really been designed to change the output of the renewables to that single-phase electricity.”

One option is to use standard domestic inverters, “but they only go up to about 10kW. That’s important, because on an installation that’s likely to be around 5MW you need a huge number of them, which would be quite unwieldy and quite expensive. The other option is to use a very large piece of kit called a static frequency converter, but these are massive and they’re normally used at national grid level. They cost around £1m per megawatt.”

However, Riding Sunbeams thinks it has a solution. The company is proposing to develop a new piece of equipment called a converter, using repurposed railway equipment, that could meet the size and price requirements for a commercial product. That will depend on bringing in investment and establishing suitable partnerships, so progress is still at the early stage.

There's a bit more about this experiment in Aldershot, and the study for the Welsh valleys (http://www.firstgreatwestern.info/coffeeshop/index.php?topic=21387.msg262617#msg262617), in this IET mag article (https://eandt.theiet.org/content/articles/2020/05/rail-solar-project-seen-as-stepping-stone-for-renewables/?utm_source=Adestra&utm_campaign=New%20EandT%20News%20-%20Automation%20FINAL%20-%20MEMBER&utm_medium=Newsletters%20-%20E%26T%20News&utm_content=E%26T%20News%20-%20Members&utm_term=842960). I seems they were supplying traction power, but indirectly as they fed into NR's own supply at 33 kV three-phase using standard inverters. But for their next trick:


I can see his point, though if the idea was to put the arrays in odd bits of railway land wouldn't you expect a lot of sources of much less than 5 MW? How many times 5 MW will the valleys need?