I would rather invest in the latest Asic miners instead, the s19 are already on the line of retirement, and now they are losing profitability faster, if you have multiple of them then you can add easily buy one latest Asic miner.

Less heat, more gains and also less noise.

Do not forget that if your ROI was to be made back in 2 years, running on solar panels alone will add an extra 2 years to ROI because once the sun is down you have to wait till the next day.