Tangenital, but your comment reminded me of a Top Gear episode where a car acted as a Faraday cage. Perhaps putting any vulnerable electronics inside your car would be sufficient?
Or a biscuit tin or other metal box. Or a fridge. Or a freezer.
Cars are very leaky Faraday cages. If they weren't, you wouldn't be able to use your phone inside one. Because of the glass apertures, they can only provide protection from very, very long radio wavelengths - MF, LF, and VLF, all much longer than FM/VHF/UHF/microwave.
They'll also (probably) protect you from direct lightning hits, because the discharge passes through the conductive skin and won't usually take a detour through any occupants.
Flare events won't affect your phone anyway. Deliberate EMP might, but EMP would quite likely to be a precursor to nuclear war, so keeping your phone working might not be your absolute top priority.
