The first phase of the Victorian Government's popular but messy rooftop solar rebate program was never going to satisfy the demand for household solar in the state, according to figures from the national Clean Energy Regulator.

The rebate program provided for an initial allocation of 24,000 households over the nearly 12-month period to the end of the 2018-19 financial year.

In October last year, a government spokesperson told the ABC the 24,000 rebate cap represented "an approximate 25 per cent increase on business as usual".

But according to monthly reports published by the Clean Energy Regulator, 24,623 Victorian households had already installed rooftop solar systems during the previous eight months from January to August 2018.

On these numbers, the Victorian Government's scheme was always going to fall short of demand for rooftop solar.

On top of this, the rebate prompted a spike in the number of solar installations, which increased by about two-thirds following the rebate announcement.

When the ABC approached the Department of Environment, Land, Water and Planning for a response to these findings, a spokesperson said the program was "designed to help Victorians on fixed, low and medium incomes, who may otherwise have struggled to afford solar, significantly cut their cost of living".

On again, off again rebates

Victoria's solar rebate program was temporarily stopped last month ( Reuters: Mike Blake )

The Andrews Government announced the rebate offer in August last year as part of a $1.3 billion "Solar Homes" package.

Most households with a combined income of below $180,000 were eligible for the scheme, which offered up to $2,225 in rebates for small generation solar units.

Although the program was capped at 24,000, the avalanche of applications pushed the number of rebate approvals to 32,000 before the Government decided to temporarily stop the program last month, with the intention of re-opening it in July.

Solar Victoria last week re-opened the rebates to customers who had already installed panels, but had been locked out of the program after the temporary stop in April.

The Victorian Government expanded "Solar Homes" in the latest budget, providing more rebates and low interest loans for householders, and that will now also include renters.

The program is expected to subsidise rooftop solar, home batteries and solar hot water for 770,000 households in Victoria over the next decade.

The Andrews Government says funding will also be provided in the program for training, safety and quality audits.

'The disappointment of it'

John and Allison Taylor missed out on the solar rebate by just hours. ( ABC News: Sybilla Gross )

Allison and John Taylor spent about $4,000 on a rooftop solar system to power their home and family business in Williamstown, in Melbourne's south-west, in April.

"We're drawing less from the grid so we're providing for ourselves a bit. It's a 'feel good' thing," Ms Taylor said.

They expected the rebate process to be fairly straightforward, but when Mr Taylor went to apply for the rebate to get half of their money back, he found the program had suddenly closed just hours before.

"It's more just the disappointment of it, not that it would change anything. You would still put panels on," Mr Taylor said.

With the rebate program now back on track, Mr Taylor said he was going to reapply for the cash he expected to get back the first time around.

'Solar-coaster' of government rebates

Business owner Tarak Shah wants to see a more sustainable rebate system. ( ABC News )

Melbourne solar retailer Tarak Shah owns one of the many companies affected when the Victorian Government hit the pause button on the solar rebate scheme.

He was forced to let five staff members go from his company, Sunrun Solar, after the temporary rebate freeze left the business with about 10 per cent of the work it had previously.

"It puts a lot pressure on yourself as a business owner, you know, when you have to look after not just yourself, but probably about eight or nine of your employees, plus your installers, their workers, and their families," Mr Shah told 7.30.

"If they don't get work, then of course they can't put dinner on their plate."

He said government rebates had made business unsustainable long-term, with months of barely any income, followed by surging demand.

"Every time there is a government announcement related to the solar industry, all of a sudden there is a 'solar coaster'," Mr Shah said.

"The customers will jump on board, but then as soon as the rebate stops, all those customers will jump off."

While he supports government incentives, Mr Shah said he wants to see a more sustainable approach to rebates.

"When it comes to having no work for two months because, you know, it's stopped and there's a re-opening date on it later, it's hard for the customers to make that decision to buy now."