my solar inverter 1.2 Kva Inverex gives error code 12 and start beeping and shutdown all load. There is no pattern of occuring this error. Sometime it occurs after 1-2 hours and sometime after 2-3 days. The error pops even when everything (except battery) is disconnected. I took to service center and after 2 visits i asked him to change the NTC heat sink sensors. But no luck. can any one help me to rectify the error. Thanks