I'll quickly add my responses on the thread:
- *REPD issues*. All of Rob's points taken, but we mustn't forget that OSM data have always been acquired and refined iteratively. Of course data from REPD has to be taken with a pinch of salt, but at least for now it's very useful for hunting for missing installations. In practice I've found most REPD installations relatively easy to resolve (but see below for an exception). Russ does compute a power output for those sites which don't have the output explicitly tagged, so there is the potential to compare the REPD output and a computed value based on area. - *ML & Solar Farms.* Tyler Busby has been working to identify rooftop solar using machine learning. He has a MapRoulette challenge running for Austn Texas at the moment. I imagine it might be possible to reuse some of his techniques to identify individual rows of panels within solar farms, which could improve power estimation from OSM data. - *Sections in Installations*. Exceptions, such as single installations with multiple sites certainly exist too. I recently mapped panels on the site <https://www.openstreetmap.org/#map=15/52.7803/-0.9372> of the former Asfordby super pit. There are two groups of panels which a Geograph photographer calls, on the basis of photos of ancillary electrical plant, Asfordby A and Asfordby B <https://www.geograph.org.uk/photo/5925161>. There are also photos of Asfordby C. As usual more can be learned from on-the-ground visits, but as above this is for future refinement. - *Rooftop angles*. I had a futile attempt to try & calculate roof angles from Lidar data. The 1 m resolution doesn't seem to be adequate. Maximum roof height is more reliable (available for instance via the dataset). Estimating the height of eaves can be done from Lidar, but it's fairly fuzzy. I think using rules of thumb for different periods of construction may be just as fruitful (perhaps 9 foot ceilings for pre-WWII, 8 foot for interwar housing, and 7 foot 6 thereafter, with 1-1.5 feet between floors). Counting courses of bricks would give a more precise measure and only needs to be done for basic ranges of housing. Most local archives are likely to have architects drawings for houses built as council housing which is perhaps a third of the total stock. However a basic estimation of eave level from 5-6 m will not be hugely out. See next bullet for a suitable tag. - *Other tags*. After much faffing about, and on Russ' advice, I have now moved to using location=roof instead of generator:place or generator:location. This doesn't work if the generator tags are placed on the building as is the case for some places in the West Midlands, but as these result in gross over-estimation of likely output I'd regard this as an interim stage of mapping. I'm still using generator:orientation, but this may also be more unwieldy than required, and obviously relates to solar installations only. Modules are tagged generator:solar:modules which at least unambiguously shows that it relates to the panels, so despite the unwieldiness something similar for angle would be clear. (As an aside I don't think we have any UK solar farms with panels mounted on heliostats, but they certainly exist in Spain, for instance at Almaraz). - *Power tagging*. One thing which has become clear is in mapping groups of panels within a solar farm and retagging the outline as power=plant isthat the use of generator: and plant: tags is unfortunate. Most of them would work just fine as they were originally with power. - *Solar arrays vs solar panels*. The current tagging largely seems to fail to distinguish between a large array of solar panels and single panels consisting of a few modules. I really don't think we want to end up having to map each group of panels individually so it would be nice to have a better way of distinguishing them other than location=roof and overall area. Perhaps less than half the area of an array of panels will be the actual footprint of panels. Also I'd be unsurprised if some don't map solar-powered rubbish bins, parking meters, road signs with power=generator too. Lastly big thanks to Jez, Dan, and especially Russ for his updates to OpenInfraMap which really help with the mapping. Jerry On Wed, 10 Apr 2019 at 23:01, Dan S <danstowell+...@gmail.com> wrote: > Hi all, > > Thanks for the comments on solar panel mapping. (Plenty of mapping > happening already: thousands of UK solar panels added to the database > in the past month.) A few small responses: > > SOLAR FARMS: > > I'll defer to Russ's tagging advice about solar farms: power=plant > polygon (or sometimes multipolygon) as the outline of a solar farm, > with power=generator areas contained within it for the blocks of > panels. Previously, I was mapping solar farms as relations, but I'm > easily persuaded! > > I don't have any advice about landuse/landcover other than that it's a > fairly separate issue, since those tags are not essential to the solar > power mapping. > > I've been adding some solar farms that are listed in the REPD list on > the wiki. For those ones I've used a tag "repd:id=*" which I hope > makes it easy to identify them using the ID number in that database. > Some solar farms have more than one entry in the REPD (they submit a > new application form when they have an expansion). > > ROOFTOP SOLAR: > > For various reasons, if we can get solar installations mapped as areas > not just nodes, that'll be helpful. Areas will be more useful than > module-counting. However, I've noted that the imagery doesn't always > make this easy for rooftop solar: clarity is variable per region. > > Is there any good way to tag the vertical tilt of a panel? I know in > many cases we won't be able to measure it well, but I thought I'd ask. > For example, there's roof:angle=* for the slope of a roof, which is a > mildly related concept. > > Cheers > Dan > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-gb >
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