&gt; We&#x27;ll break even in terms of costs within 4 years.<p>That means a loan of up to 25% interest could have financed the solar panels.  Are interest rates higher than that for your parents?<p>&gt; The increase in productivity is massive. I no longer have to deal with heat when I go home.
&gt; Now imagine this happening for billions of people living in tropical climates<p>For what it&#x27;s worth, the GDP per capita of Singapore used to track the introduction of air conditioning.   Not sure what&#x27;s cause and what&#x27;s effect, or coincidence.