Don't just take the cheapest and other expert tips to find the best solar installer

Picking the right solar company can be overwhelming, with thousands to choose from.

Many will do a solid job, so why not take a shortcut, go with the cheapest quote and hope for the best?

Experts reckon that is a really bad idea.

It could leave you out of pocket or with an unsafe, damaged or poorly installed system that underperforms.

There has been a surge in demand due to the Albanese government's multi-billion-dollar Cheaper Home Batteries Program, with more than 600,000 households installing solar batteries since July last year.

While that has led to a clean energy boom, the ABC has uncovered shocking stories, from customers begging companies to fix dodgy installations, to people who lost large deposits after a business went bust or waited a year for a system that didn't show up.

There has also been a spike in complaints to consumer protection agencies, with unresolved disputes clogging courts and tribunals.

Pressure on the government to reduce spending has also led to speculation the program could be cut back, which could spark another battery rush.

To help consumers make decisions, Solar Choice's Jeff Sykes and Finn Peacock from Solar Quotes — both leading comparison sites — gave us their best tips.

These are the steps they say will give consumers the best chances of avoiding nightmare solar installations.

The magic number of quotes for a rooftop solar or battery system is three.

Be wary of the cheapest, Mr Sykes warns.

Companies with low prices could be using budget products or cutting corners with a cheap installation crew.

"You're likely to end up having product failures or issues with your system that are costly and difficult to rectify, particularly if you've used an installer that doesn't have a good reputation," Mr Sykes said.

Mr Peacock said ridiculously low prices could indicate bad intentions.

A rogue operator could be planning to sign up heaps of customers and shut down when the bills come in.

"One way to deliver a very cheap system is if you know that you're not going to be paying your taxes or your wholesalers or your installers," Mr Peacock said.

Use the free Australian Business Number platform to check how long a company has been around and what trading names they have used.

Avoid any company that has gone bust and restarted under a new name — a notorious solar tactic, according to Mr Peacock.

"You're buying solar panels that are warranted for 25 years. You're buying a battery that's warranted for 10 years," he said.

"You want a company that's got the financial breathing space to have staff that are dedicated to customer service and maintenance calls."

Skip the glowing reviews and devour the gritty ones.

Mr Peacock says one-star reviews are what consumers should be paying attention to.

While all companies make mistakes and some customers have unreasonable expectations, how a business responds when something goes wrong reveals a great deal, he says.

"If they haven't addressed it whatsoever, that means that they probably don't care," he said.

"If they've addressed it in a kind of menacing way and blamed the customer, that also tells you a lot."

Mr Sykes warns overall review ratings can't always be trusted.

Some companies can "game" review platforms by encouraging customers to leave positive comments and others may boost their ratings with fake reviews or by getting bad reviews removed.

"(Companies) having a high quantity, potentially with fake reviews, they can just get past that kind of sniff test that a lot of customers do," Mr Sykes said.

Comparing scores across different review platforms is worth doing.

He also suggested people ask for a few local customers they could speak to for a reference check.

Check the accreditation of the company and the installers that will do the work — the requirements vary depending on where you live.

Each state and territory has a website where customers can check the electrical licence and sometimes if an installer has faced disciplinary action.

Nationally, Solar Accreditation Australia signs off on installer credentials.

There is also a voluntary industry scheme, the New Energy Tech Consumer Code (NETCC), which lists approved sellers.

The NETCC publishes which companies have been suspended or expelled for bad behaviour.

Since the federal battery subsidy began, unscrupulous solar companies have been upselling consumers systems that are much bigger than their energy needs, prompting a redesign of the scheme.

Those big batteries were often paired with a tiny inverter.

An inverter is needed to convert the energy into electricity.

Having a small inverter means that, even if you are charging the battery at full speed, it takes hours to fill and then discharge, which could mean missing opportunities to sell electricity back to the grid at the best time.

A free government website offers detailed advice. As does the New Energy Tech Consumer Code.

Each state and territory also has advice specifically tailored to where you live.

Before paying the deposit — check the warranty details and avoid promises over the phone, especially about the installation date — get it in writing.

Some consumer protection agencies recommend paying the deposit with a credit card because it means you might be able to claim a bank chargeback if anything goes wrong.