His name has two meanings. One of them is Sōlis, the genitive of Sōl (Sun); so one possible reading would be Yue Hu as Sun's, of the Sun, Solar. The other is Sōlīs, ablative plural of sōlus (lonely, loneliness); as if Solis was born by the loneliness of Yue Hue and Fei Liai.
I'm almost sure the author just meant the first reading, but the second one IMO makes the name way more interesting.
And since we're at this:
[ul]Filius = son
Filia (Fei Liai) = daughter
Unus (Wu Nusi) = one
Duo (Du Wo) = two
Tres (Torres) = three
Nubes (Nubess) = cloud
Fulmen (Furman) = lightning
Pauus (Pa Wusi) = peacock
Spina (Speyna) = thorn
Imber (Yin Bo) = rain, storm [/ul]