From: blockedofcourse@foo.invalid   
      
   On 12/1/2025 4:30 AM, Martin Brown wrote:   
   > On 30/11/2025 22:16, Don Y wrote:   
   >> Something optically clear, temperature range of -40C to +60C (70C would   
   better)   
   >> that can tolerate daily changes of ~30C for ~20 years.  Ideally, adherent   
   to a   
   >> variety of surfaces but I can compensate, if necessary.   
   >   
   > If it is optically clear it won't stay that way for long under hot UV desert   
   > conditions. You can't put enough UV stabiliser in to keep it clear for long.   
   > Most materials that tolerate UV have a surface coating.   
      
   Most devices aren't exposed to UV (though some are).  But, all will be   
   exposed to those temperature extremes (the -40C in other parts of the   
   country, not here).   
      
   > Even in the UK clear weatherproof potting compositions on cheap solar cells   
   > yellow and deteriorate to crazed opaque surface in a matter of a few years.   
   The   
   > expansion and contraction will also be problematic.   
      
   Dunno.  Here they are glass coated.  The real risk is from hail (not   
   common, here).  I've had one sitting in the side yard for almost 7 years   
   and it still looks "new".  (no place to install it)   
      
   >> And, not exhorbitantly priced (I need gallons of it)   
   >   
   > It will have to be exhorbitantly priced. Or opaque absorbing or reflecting UV   
   > away will protect the bulk material.   
      
   Up to now, I've been having "glass inserts" designed and making enclosures   
   that can accommodate them (properly sited, etc.).  But, they add cost and   
   labor.   
      
   A simpler solution would just be to pot the assemblies and let the compound   
   provide the "clear" aspect that the glass has been providing.  It also makes   
   them more durable (think installers dropping them and jarring their internals   
   as well as potential alignment).   
      
   If I switch to an opaque compound, then it *only* addresses the durability   
   issue (and, only partially) -- but, does so at the expense of requiring   
   other measures to keep the "optical" paths clear of compound during   
   manufacturing.  (and, still requires all the costs of the non-potted   
   approach).   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)