an investment don't mean you get money if you infestment fail you lose the money but also the Government lose to.
if you test your own product its not private use you always have risk
"because I maybe will sell that."
you don't need to sell it you also can just use it for your business
yes you understand much better now but you still think you only can do this if you sell it.
for example you don't have to sell your or any computer to do this with your computer.
another good technique for a investment is a Heat recovery ventilation system http://en.wikipedia.org/wiki/Heat_recovery_ventilation
you can get it cheap for only 440€ : http://www.bayernluft.de/de/frame.cgi?page=start
brings you profit by saving heating costs!
ok harz4 don't pay for heating costs but you still can sell it to some non harz4 people.
also its an investment in fresh air and with the economics you can force social welfare office to pay it because its economic and green and so one.