Solar module prices have dramatically dropped in recent years, which in turn has facilitated distributed solar energy resources (DSERs) in smart grids. To manage electricity real time supply and demand, the utilities has shown the strong interest in deploying virtual power plants(VPPs) which enable solar generated energy trading to reduce the intermittent DSERs impact in electric grid. Unfortunately, the current energy trading approaches in residential VPPs typically require a trusted third party to take on the role of the middleman, DSER users are not allowed to trade their surplus solar energy independently and simultaneously to maximize potential benefits. In addition, these approaches do not achieve "fair" for both VPPs and DSERs users. To address this issue, we build a multi-agent deep reinforcement learning based peer to peer (P2P) new solar energy trading system-SolarTrader+, which enables unsupervised, distributed, and long term fair solar energy trading in residential VPPs. We apply deep reinforcement learning with neural networks as Q-value function approximator.We implement SolarTrader+ and evaluate it using data from U.S. residential VPP communities that are comprised of - 119 residential DSERs. Our results show that SolarTrader+ can reduce the aggregated VPP energy consumption by 83.8% when compared against a non-trading approach.