@Richard Connelly I have found that with most lichen here in Australia, especially the baked on lichen that has been there for some time, there is literally no alternative but to scrape it. The brush you use also makes a difference. Most rotary brushes and even robotic cleaner brushes just don't get the job done. I have seen @Kim Verduyckt's videos from Europe of really really bad lichen cleaned with the aid of LRA and a SolarCleano F1. The difference is amazing. With advice from Kim, I attacked a bad lichen job here in Australia with a similar approach (I don't have heated water, whereas Kim did have in his setup). At the end of it, despite 3 applications of LRA and 6 passes with the F1 along with the red bristle (hardest), I reverted back to scraping the chunks off with the solar safe scraper as the hardest bristle on the F1 simply did not cut the mustard. Once I dislodged it with the scraper, then it made things better. So my take aways from that were: 1) Aussie lichen is perhaps different to Europe and 2) I probably need to got for a heated water setup. That all said, our guys still use LRA in daily resi work, because it not only helps remove the foliage but also helps us remove the residual brown/black marks that get left behind on the panel surface that remain after foliage is removed. These can look real shit if you don't clean them, and they're not easy to remove sometimes. (Nothing worse than seeing them on a dry panel you thought was fully cleaned 😪). There are some people that will say you can just hit it with water and plastic scraper, with no LRA. And on some occasions, that method will totally get the job done, no arguments there. But on the flip side, 1) it can also end up being a bit harder work, thus take longer and 2) we've found that you're more likely to end up with those brown/black spots on the glass after the panel dries, which then means you will need to go back and clean again.