Time-shiftable loads, also known as deferrable loads, such as charging of electric vehicles, washing machines, dryers, are able to provide scheduling flexibility for demand response. This can help to reduce the energy cost under the condition of dynamic electricity pricing. It can also facilitate deeper integration of renewable generation by absorbing variability. According to the environmental conditions and real time market price of electricity in Singapore, two real-time price-based scheduling algorithms are proposed and studied in this paper. Simulations were conducted with different percentages of deferrable loads and solar penetration levels, with about 1 million devices participating in the demand side management program. The results show that the proposed algorithms schedule tasks resulting in a significant reduction in electricity bill cost. The algorithm was further modified to include demand and renewable generation forecasts to mitigate the problem of variability, which resulted in deeper possible renewable penetration and better system stability.