I had 'greentyre' solids on a bike that i used on the towpaths. They were bloody awfull, the effort to pedal was higher than on pneumatics, on soft going they were hard work as the footprint was smaller than pneumatics so the tyre sank in and on tarmac etc they could slide out from under you very easily being made of plastic rather than rubber which has a better grip. As well as the problem that they wrecked the wheels by breaking the spokes cos they transmit a lot more shock thro to the wheel which also showed up in that after some time i would find my hands tingling from the transmitted vibration and one day the jolting thro the saddle put my back out.
Changed over to Schwelbe Marathon Plus and still had punctures so fitted 'Slime' tubes. That cured it but eventually you will get a flat tyre that wont blow up or reseal as the slime is exhausted, removing the tyre to change the tube the sight is that the tube is absolutely covered in tufts of fluff and the inside of the tyre is riddled with thorns, i think there was something like 50 thorns in each tyre. Now the slime is a double dose plus slime thorn bands.