Local experts say investing in solar energy can now bring solid returns while being friendly to the Earth.

The cost of solar is constantly dropping, and in some cases can be lower than, or equal to, the price of conventional power sources.

Nathan Lim, portfolio manager at Australian Ethical Investment, says it is time to get on board to profit from the future of energy.

He gives six key reasons to invest in solar.

1. SOLAR HOMES SAVE MONEY

“Increasingly affordable solar power is driving unprecedented global demand that has resulted in annual growth of 43 per cent over the past 10 years,” Mr Lim told AAP reporters..

“Companies providing goods and services to meet this demand have a bright future.”

2. COSTS ARE FALLING

Research in the US has shown that the installed price of a residential solar system is down 61 per cent over the past 15 years.

Mr Lim said new preliminary data suggests the price will continue to trend downward for small and large-scale solar, and might even have accelerated.

3. SOLAR STOCKS HAVE FALLEN

“The recent underperformance of solar stocks represents a good buying opportunity for investors,” Mr Lim said.

“We believe the market is making the mistake that a falling oil price is bad for solar companies.”

4. SOLAR IS SPREADING

“Energex has just announced that 27 per cent of detached homes in southeast Queensland now have solar on their roofs,” he said.

“Similarly, SA Power Networks recently reported that 23 per cent of homes in South Australia have installed rooftop solar.

“The unsubsidised economics of solar in this country are so good that households are increasingly going solar without much prompting from policy.”

5. POLICY CHANGE IS COMING

Mr Lim says it is strongly expected that greater uniformity on tackling climate change through renewable energy will be the result of the 2015 United Nations Climate Change Conference in Paris later this year.

“Greater co-ordination between governments and a general acceptance of the need to reduce our aggregate emissions intensity would be a tailwind for the entire industry,” he said.

6. THE SUN WILL CONTINUE TO SHINE

Quite simply, fossil-fuels and other mineral-based power sources will run out. This will almost certainly happen before the Sun goes supernova.

“Every roof that has a clear line of sight to the sky is well-placed to accommodate solar,” Mr Lim said.

“Solar has a bright future and companies tied to this industry have only started to feel the market's full potential.”