Multi-family housing units, many of which will also have to have solar panels under the new rule, are not included in the forecast.
During the recent voting, the California Energy Commission voted 5-0 in favour of the legislation under which it will be mandatory for all new houses and buildings - up to three storeys - to install solar panels by 2020.
Adding solar panels would boost construction costs by $9,500 for a single-family home but save owners about $19,000 in energy and other expenses over 30 years, the Energy Commission estimated. It represents the state's latest step to curb greenhouse gas emissions. Some of that had been included in GTM's earlier forecast, because even without the mandate a certain percentage of California homes go solar from the start. Vivek Sharma, Senior Director, Crisil Infrastructure Advisory, said: "The Central Electricity Authority and the Central Electricity Regulatory Commission will have to come out with norms that can allow the sale of hybridised power generated from existing projects".
However, an analysis by the federal Institute for Energy Research (IER), said this mandate could increase home prices by more than expected.
Trump stumps for Republicans and debuts new campaign slogan in Indiana
The Indiana rally comes as the president has told advisers he is eager to ramp up his campaign travel on behalf of Republicans. Donnelly, Trump said, will "say one thing in Elkhart" and then support the "radical, liberal agenda".
California, the most populous state, with almost 40 million people, has positioned itself as the nationwide leader on clean energy, pushing for more electric vehicles on the roads and lower emissions from homes and commercial buildings.
"That's just going to drive the cost up and make California, once again, not affordable to live", Assemblyman Brian Dahle, the chamber's GOP leader, said Tuesday. The key objective of this policy is to provide a framework for promotion of large grid connected wind-solar PV hybrid system for optimal and efficient utilization of transmission infrastructure and land, reducing the variability in renewable power generation and achieving better grid stability. Some homes that are shaded by trees or taller buildings, or have roofs that are too small for panels, would be eligible for exceptions.
Clean energy projects in the country are set to gain in terms of cost savings on land acquisition and evacuation infrastructure under the National Wind-Solar Hybrid Policy.