There are two very important aspects of solar heating that cannot be ignored.

#1 Heat gain is proportional to the surface area of the panels. 150' of 1/2" hose has the equivalent surface area of less than 10 sq-ft which is only about 5% of your pool area so you will end up with very little heat gain.

#2 Heat transfer efficiency is dependent on flow rate. The higher the flow rate, the more efficient the heat transfer (i.e. less heat is lost to the environment). If you try to force water through the small hose, you are going to severely restrict the pump and have very little flow rate through the hose so the efficiency is going to be very poor. Not to mention reduced filtering.

If you want to build a more effective solar panel, you need to use many parallel runs of hose to reduce the head loss like most purchased panels have, plus create a surface area that is at least half of the pool area. But you might find that buying a cheap panel on ebay is easier and cheaper.