This paper describes the fundamental study about utilization of co-glycerol (CG) derived from biodiesel fuel (BDF) production especially exhausted from small BDF plant which has no facility to dispose them by themselves. The method to add value to this CG is refining and production of pyrolysis oil under low temperature around 500 °C, using small solar thermal collector (STC) with type of parabola trough as its heat source. Compared with the previous study, this paper especially focuses on an evaluation of the quantity of CG to be treated from single collector. As a result, the maximum quantity of co-glycerol to be treated from single STC once at a time was equivalent to a half volume of test tube, which was inserted inside STC and its length was almost the same as that of STC, and this was limited due to the occurrence of bumping and flowing out without refining. However, this problem was mitigated by dynamically reducing the area of parabola-trough mirror, then reduction of rapid increase of temperature inside STC. Furthermore, the batch type systems exchanging the test tube containing CG is adequate for increasing the amount of CG to be treated by this STC.