Heliostat mounted panels/reflectors

I just happened to be looking through MapRoulette challenges and found the one on converting nodes to areas (not sure how to link to that here).

One issue I realised on looking at it is that in Extremadura, Spain there are many heliostat mounted solar pv panels. In particular the concentration of solar farms around Almaraz are nearly all like this (mapillary). I know of these because I first noticed them in Feb 2010. Almaraz has a nuclear power station and therefore the area already had excellent grid connectivity.

Unfortunately someone has diligently converted all these to areas, which would be misleading for data purposes.

We need to work on a couple of issues in order to be able to capture data on such plants accurately:

  1. Agree on a tag to indicate that a relevant solar panel is mounted on a heliostat. Options I can think of are location=heliostat (consistent with existing tagging for roofs, reducing data consumption issues); support=heliostat (consistent with most widely-used tag for supporting structures); man_made=heliostat.
  2. Do something about the existing power=heliostat which refers to heliostat mounted mirrors in solar thermal stations (also common in Extremadura). Probably this should be refined to something like heliostatic_mirror to be more precise & remove confusion.
  3. Include stuff about such plants in any MapRoulette challenge rubric.
  4. Select a suitable tag for the whole solar farm to indicate that the panels are mounted on heliostats.

According to Spanish Wikipedia the individual panels at Almaraz are around 11kW, suggesting 44 modules at 250W/module. They look to have more solar modules (perhaps 4 rows of 14, giving 56) and as installation was prior to 2010 likely to generate less power. Other installations

Domestic heliostat mounted solar pv is also available: http://www.heliostaat.nl/


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I had in mind to propose orientation=heliostat. It expresses that the orientation is not a fixed value, and is compatible with other tagging. What would you think to that?

Can you clarify why making them areas is problematic? Is it because they’re tracing outlines which will change? (Excessive detail?)

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If tracing as areas they will reflect the orientation of whichever imagery layer is being used. The examples I’ve looked at range from due E to due W or thereabouts. This is one I have mapped: https://www.openstreetmap.org/query?lat=37.26305&lon=-3.13195 (this seems to be the one with good photos on Wikimedia) near Guadiz using sun_following for orientation, but heliostat would also be clear. (There’s a big solar thermal installation by the motorway to the E as well using parabolic troughs, I think this one https://en.wikipedia.org/wiki/Andasol_Solar_Power_Station).

This is one at Almaraz where the imagery must have been taken late in the day: https://www.openstreetmap.org/way/720148998#map=16/39.8313/-5.6038&layers=D. If you toggle layers other orientations are shown. At least some heliostats around Almaraz have have 2 axes of rotation, so apparent area will not be constant.

One alternative would be to map them all oriented to the S, which would merely involve appropriate rotation of data already added.

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