Is $51,000 to pay off an 8.8KW solar lease a fair price?

My father passed away recently, and I discovered he had purchased an 8.8KW system from SunRun a year or two ago. It is a 25-year lease at $250/month, and they quoted me $51,000 to pay it off. I don't want this system, and they've refused to come take it back, stating they will lien the house if payments stop. I don't think my dad was in his right mind when he signed, as he had recently lost his wife. I am looking for legal options to get out of this contract before contacting an attorney.