Well I am not sure about Solitaire in particular but for a lot of games this is possible. If you buy a Mac game on Steam it will almost always have the Steamplay designator on the page that means you can download and play that same game on a Windows PC too. This is true with some titles on the Origin service as well but selection of games for both Mac & PC is very limited with them. Last but not least any games you buy from GOG.com for Mac also include PC versions. GOG is a great place for classic games if you are not familiar with them and they tend to be inexpensive too.
It is only for Mac on the Mac Appstore but there is a really nice Solitaire game there that is free with only one in-app purchase they rarely pop up an offer for which just gives you even more solitaire variations. This game is called: Full Deck Solitaire and I'd encourage you to download it for free and enjoy. I keep meaning to buy the in-app purchase for that even though I don't care about the additional games myself just to thank them for the game I enjoy so often. It always seems to pop up the offer when I am broke and then I feel guilty because I love their game!
I hope that helps you out.
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Oh, by the way you probably know this already but just in case, Windows does include a simple Solitaire game. It's not anywhere near as nice as the one I recommend for Mac but it isn't terrible either and the price is certainly right.