... 8-3030pcsØ 58mm1.8MHas240L3.40 For solar collectors, if you need 300L, you can use two sets of SC58-1.8-18 ... . 400L, you can use two sets of SC58-1.8 ... 24. 500L, you can use two sets of SC58-1.8-30. We, Changzhou Erjin Solar-Energy Equipment Making Co.,Ltd, ... more information, please check our website or contact directly. SRCC solar water heater-- Solar Collector