os/profiles/cachix/pub-solar.nix

{
  nix.settings = {
    substituters = [
      "https://pub-solar.cachix.org"
    ];
    trusted-public-keys = [
      "pub-solar.cachix.org-1:ZicXIxKgdxMtgSJECWR8iihZxHRvu8ObL4n2cuBmtos="
    ];
  };
}