Build the tricycle yourself ! . . . . A
Tricycles are plentiful although the price may shock you.Do a search for VelomobileHPV recumbent bikeRecumbent bikesBentsHowever few will come as solar powered. Depending on where you live this may be a lost cause anyway unless yu get a LOT of sunshine. Battery power is more realistic with the possibility of getting 50 0r 60 miles range fairly easily - more if you happy to peddle to help out.