If you have stable 500w from solar panels you still need a bigger power supply at least a 750W i personally would still opt for eth mining with some powerful gpu
yes but will this be long term? in August there will be merge of ETH 1.0 and ETH 2.0 to ETH 3.0
When it will no longer be possible to mine eth you can switch to other altcoins, with less profit it is true but the alternatives there are some examples ergo, ravencoin, ton, etc