CANBERRA, Aug. 15 (Xinhua) -- Australian researchers say rooftop solar owners can earn more by selling excess power to neighbors, reducing grid strain.
Published in Renewable Energy in the Netherlands, the findings come as nearly 40 percent of Australian homes adopt rooftop solar and seek better renewable economics and grid stability, according to a statement released Friday by the University of South Australia (UniSA).
The study found peer-to-peer (P2P) energy sharing can be more profitable than feed-in tariffs, now under 5 cents/kWh in the Australian state of Victoria versus retail power at about 28 cents.
"Selling surplus PV (photovoltaic) energy directly to neighbors at a mutually agreed price in between can be more profitable for solar householders and still cheaper for buyers," said the study's lead author UniSA researcher Kevin Wang.
UniSA and Australia's Deakin University researchers modelled grid sales, battery storage, neighbor sales, and a combination of batteries plus P2P trading, using data from a solar home in Geelong, Victoria.
P2P sharing cut grid use by over 30 percent and yielded the highest solar returns. A 10kWh battery with P2P earned an estimated 4,929 Australian dollars (about 3,208 U.S. dollars) in 20 years, while grid-only sales showed negative returns due to low tariffs and battery costs, Wang said.
The study also found that while batteries increase self-consumption, up to nearly 38 percent in the battery-plus-P2P model, they can reduce the amount of surplus energy available to neighbors.
"Battery size proved critical. Systems with oversized batteries saw returns diminish due to higher capital and maintenance costs and reduced surplus energy," Wang said, adding smaller battery sizes produced the shortest payback times.
Researchers urge optimizing battery size and P2P pricing to benefit both sellers and buyers and ease grid stress, calling for supportive rules and technology to scale up. ■
