Earn $100 When You Refer a Friend Posted by Norwall PowerSystems | Mar 2, 2015 | News Earn $100 When You Refer a Friend You know how important your KOHLER® generator is to your home or small business. Suggest one to a friend, and earn a $100 rebate when he or she purchases a KOHLER generator between March 1 and December 31, 2015. Earn $100 When You Refer a Friend