Rooftop Solar Part 2 – All you need to know before you start (off-grid guide)

Rooftop Solar Part 2 is bound to shock you – not literally – but by some of the cowboy practices and shoddy gear they put up on your roof, all to make a buck. It is a minefield of intentional obfuscation – double speak.

As I said in Rooftop Solar Part 1 – where do I begin, regrettably, what I found shocked me. I was naturally attracted to the sports/celebrity TV advertisers, who set expectations of around $5K for a 5kW system and a battery.  Remember that figure!

Fact: The larger solar retail organisations are nothing but big multi-level marketing schemes

I found that most of the ‘big’ guys and solar comparison websites are nothing more than sales outfits—order takers who know very little about the product. They want to see your last electricity bill to quote a matching kW capacity from the price list.

This is passed onto a network of local subcontractors (subbies) to deliver. They can’t make enough money from the sale and must advise that the ‘package’ won’t work at your place for some obscure reason and upsell to make a profit.

Typical ‘extra’ costs are exorbitant scaffolding prices, organising a new smart meter (your retailer will do that for free), new cabling from the meter to the inverter (seldom necessary), solar panel stands (to elevate when the roof is flat), upgrading to supposedly better-suited panels, a better inverter, software charges, user training, and annual maintenance agreements.

As one CyberShack reader said, “That $5K system ended up costing twice as much due to so-called ‘essential variations’ for my standard single-level, suburban home. I can’t afford a battery now.”

We spoke to a reputable local company with a 20-year history. “The cheapest we can do a 5kW system is about $9000; if I were buying it for my home, it would be closer to $11,000. The cheap systems are rubbish. The problem is that the TV advertisers set a false expectation, and then the installer has to upsell anyway”.

Rooftop Solar is about getting a poor sucker to sign what amounts to a blank cheque. Few mass-market systems end up costing what is quoted in TV, Radio, Newspapers, or social media.

Many installers are not licensed or qualified – like the itinerant roof painters!

Only a licensed electrical contractor can commission solar panels on a residential property’s roof. The reality is that in some States, a horde of trained monkey ‘subbies’ – backpackers, fruit pickers, et al. do the grunt work to install and wire up to sign off stage. At that time, a qualified electrical contractor connects the system to the energy grid. Quality control – what’s that?

Over 60% of rooftop solar complaints to State Fair Trading Bureaus are for dodgy installs, such as roof cladding penetration (leaks), roof damage, change in rainwater flow, detaching from the frame, or just shoddy workmanship.

Another huge source of complaints is that the system produces far less than the advertised output. That is because the sales organisations don’t care which way the roof is facing, the roof pitch, etc., to produce maximum energy.

Complaints then escalate over time as cheap panels, string inverters, or other parts fail, only to find that the so-called warranty is with a liquidated company, and you have no recourse.

And solar panels need surface cleaning two to three times yearly to keep output up.

Cheap is cheap – not good

Readers have complained

• Not one ended up paying the lower advertised price, and in some cases, at least twice that.
• The string inverter (which converts DC solar panel power to AC) failed, and the system was offline. He has been told he can have a new inverter under warranty, but the only permanent cure is to replace that with micro-inverters and a new controller.
• Several ‘isolation alarms’ after grid faults have required expensive callouts to restart the system. The cure was an extraordinary cost to upgrade the wiring and install micro-inverters to stop this.
• Could not get a replacement for a five-year-old hail-damaged panel. His installer had to replace all panels at the owner’s cost, but insurance only paid for one.
• Waited a year for a technician to arrive and was billed for their time as he was from a different company doing a so-called ‘out of warranty’ job. The panel was warranted, but not the labour to remove the old one and fit a new one.
• DC arcing caused by an under-sized inverter* caused a home fire.
• The cheap panels clouded during warranty, reducing power output, but the installer and panel supplier had gone out of business.
• The energy app stopped working and is now missing from the Apple Store.
• The inverter had to be replaced when adding a battery.
• The so-called 20-year warranty was dependent on signing up for an annual maintenance program at an exorbitant price.

The common thread was that all these used mass-market, cheap systems. We are not saying all cheap systems are inadequate, but there are so many corners cut that they likely won’t meet reasonable expectations for performance or longevity.

* One of the biggest cons is quoting for an inverter with a smaller capacity than the rooftop solar system can produce. Beware of a 10kW system with an 8kW inverter. If the panels produce more electricity than they can handle, you risk panel overheating and hot spot fires.

Rooftop panel quality is often substandard

For example, the so-called Tier 1 panel classification was created in 2012 by US Bloomberg NEF (BNEF), a global commodity market research company. It is based solely on a company’s ‘bankability’. BNEF states there are many documented examples of quality issues or bankruptcy of so-called Tier 1 manufacturers. It is not a sign of panel quality.

Tier 1 means nothing—it is purely a marketing term. There is no Australian standard for quality, reliability, lifespan, company history, etc. If a company infers otherwise, consider what else it is lying about.

There is an Australian Standard AS/NZS 5033:2021, Installation and safety requirements for photovoltaic (PV) arrays, but as experts state, we don’t make panels, inverters, or batteries here. The rules are too easy to circumvent, and most installers have never read them.

The Clean Energy Council has a list of approved panels. Approval does not guarantee quality, but it does indicate that these panels ‘should’ meet approved standards. The approval also lists enhanced features, such as salt mist resistance (vital if you live near salt water).

Choosing an installer

The key to getting rooftop solar is to research and ask for at least three quotes—not just take the big retailers’ marketing BS. A Google search for Rooftop Solar and your location is a good start. Avoid any results that are ‘sponsored’. Their length of time in business is a good indicator of reliability, and checking other buyers’ references is essential.

So now, having scared the bejesus, let’s look at what you really need.

Is your home right for solar?

You need a large enough (assume panels are about 1 x 2m), sun-facing (as it moves from east to west), roof area at the optimum pitch (panel angle is basically your latitude (see pitch below).

Sydney	Melbourne	Perth	Brisbane	Hobart	Adelaide	Darwin
34°	38°	32°	27°	43°	35°	12°

So, if you want 10Kw, that would be 25 x 400W panels (approx. 50m2). Few homes have that ideal area. Many have the wrong sun-facing angle (instead of east-west, they are north-south), some are hip-style (like a pyramid), some are flat, and some are in the shade (from adjacent buildings) during the day.

Flat and lower-pitch roofs reduce efficiency, as shown below. Frames can elevate panels but use even more roof area to avoid overshadowing other panels.

Sydney	Melbourne	Perth	Brisbane	Hobart	Adelaide	Darwin
87%	86%	88%	90%	82%	87%	96%

If you have the wrong roof and a single-string inverter, your installation could output a fraction of the power. Alternatively, you may need to buy far more panels to get the kWh capacity you thought you paid for.

If you have a complicated installation, avoid the cheapies and call in an expert for an accurate quote.

Other issues that can cost more include

• Access/distance to the electrical sub-board or main board.
• If your mainboard is old and does not have the correct meter (smart meter replacement is usually free)
• Access to Wi-Fi on the rooftop so the panels, inverters and batteries can be controlled (Wi-Fi is often unavailable on a roof, and you may need to place a mesh node in the ceiling space.)
• Ease of getting 20 or more panels up to the roof and whether scaffolding is needed or just ladders and platform planks.
• Whether you are in a hostile environment like a marine area that could cause oxidisation of connectors and panels.
• Whether you are in a hail zone and need hail-resistant panels.
• If you are in a Strata-titled complex, you will need Strata approval, possibly a DA, Construction Certificate, etc. Once installed, Strata will need to increase insurance to cover storm damage, but you will pick up all maintenance and other replacement costs.

What size do you need?

A 5kW system is for smaller homes. Larger, all-electric homes with an EV may need 10-20kW systems.

As reported in Rooftop Solar Part 1, I have over five years of statistics from an  Emberpulse monitoring system. It tells me that I need to cover an average baseload of at least 500Wh (Watt hours) to keep the smart home going – that is 12kWh in a 24-hour day.

My average energy use varies from about 250kWh per month (25,000 Watt-hours or 8.3kWh per 24-hour) in Winter to 450kWh in summer (45,000 Watt-hours or 15kWh per 24-hour).

A 10kW (10,000W) system should produce 15-30kWh during a 10-hour sunrise-to-sunset day—less in cloudy conditions.

If you don’t have a battery, that power is converted to AC by an inverter (typically <90% efficient). With everything going, we need up to 6000W load, so the system may need to be supplemented by grid power when needed and overnight when solar panels do not work and the battery may be exhausted.

A 10kWh DC capacity battery (stores 10,000W) will provide about 8000W AC for an hour, 4000W for 2 hours, 1000W for 4 hours, etc., via an AC inverter.

So I need a 10kW system and a 10kWh battery. We hope that a battery will cover our nighttime energy needs. It is important to select a battery system that can expand. Start with 5kW; if that is not enough, add another 5kW (more batteries can usually be added).

Don’t be confused—a reputable solar installer can calculate your use based on your past 12 months of electricity bills.

Panel options and what to look for

Rule #1 – forget the Tier 1 marketing BS.

Most roof-mounted panels will be around 400W and have a theoretical efficiency of 20%—the higher the efficiency, the better. Each panel typically produces 1-3kWh per 10-hour day.

The best panels are monocrystalline, containing split cells linked by busbars. They are encapsulated/sandwiched between a tempered glass sheet and a backing sheet. Most tempered glass will handle 25mm hail at up to 100 kph.

But if you live in a severe wind environment, you must specify a front/rear load wind resistance, generally 5000/4000Pa. You must specify IEC 61701 certified, level 6 panels if you live in a seaside area. These tend to use Tedlar PVF back sheets instead of the usual cheaper PET or Polyethylene. You can read more here. You can read more about panel types here.

Again, don’t worry too much if you use a reputable supplier who understands your needs. The bottom line is that cheap panels will not last the distance and will lose efficiency faster.

Building integrated photovoltaics (BIPV) can replace your roof cladding

If you are building a new home or need to replace tiles or Colourbond, you should seriously look at BIPV Viridian panels. While they are likely to cost more upfront, you get much of that cost back as you don’t need roof cladding.

Advantages include

• No issues with birds getting and living under roof-mounted panels
• Cleaner roof line (aesthetics) than roof-mounted
• Increases property appeal and value
• Walkable
• Have a higher tolerance to hail, salt air and wind.

String inverter VS Microinverter VS Hybrid controllers

Solar panels produce DC power that needs to be converted into AC by an inverter. Cheap systems use one string inverter (all panels connect to it), which is a weak link in the chain. For example, if it fails, the whole system will fail. If one panel fails, then the entire system fails. But hey, it is cheap.

The more logical solution is to have a microinverter on each panel. This allows for a fault-tolerant system—if one panel or microinverter fails, the rest keep working. It also allows individual panel monitoring, fault reporting, and higher efficiency.

You can read more about inverters here.

Apps

Many cheap systems only have basic Wi-Fi apps that monitor the amount of energy produced and the amount of grid energy used. Some have multiple apps – for the inverter and the battery.

Smart apps cover

• Full backup: The battery is for backup only when grid power is unavailable.
• Self-consumption mode: Battery reduces the use of grid power.
• Savings mode: Calculates the least cost of power at various times and can recharge batteries from the grid if required.
• A good app will also have EV charging awareness.

Some apps have annual subscriptions because they require a cloud connection and offer app updates, advanced monitoring and analytics. As long as you see the value, subscriptions are OK.

Readers have complained that many cheap systems charge subscriptions that don’t appear to do anything.

Choosing a retail energy company

Unfortunately, you cannot go 100% off-grid unless no energy retailers service your property.

When you produce most, if not all, of your energy, the main issue is to look for energy retailers with lower daily energy connection/supply costs. Typical daily supply charges are $1-2.40 or $365 to $876 yearly.

Some retailers offer lower supply charges but may charge more per kWh for grid energy. After a few months, you can determine whether you need the lowest supply or energy charge.

Feed-in tariffs (FiT) range from 0 to 5 cents per kWh, and many cap that at between 3.5 and 5kWh per day. In the future, the grid may turn off FiT when it has too much power.

Do I need a battery?

No, but then you won’t have solar power at night with peak grid kWh charges.

Our insider says that the 5kW ‘generic’ Lithium-ion battery advertised by the mass market costs less than $2000 (retails for twice that). He would not put a Lithium-ion ‘firebomb’ on his roof. Look at the newspapers for dramatic headlines and the LG battery recalls. Read Consumers urged to check solar energy storage batteries due to fire risk.

Lithium Ion has a ‘depth of discharge’ issue. You should not fill it to over 80% capacity and discharge it to less than 20%. That means only a 60% usable capacity (3kWh). In addition, they have a vastly lower recharge cycle capacity – as low as 500 full recharges before starting to lose capacity. Do not buy Lithium-ion solar batteries.

A decent Lithium Iron Phosphate 4 (Li-Po4 or LPF) with minimal chance of thermal runaway costs about $6000. LFP can have a 100% discharge depth and over 3000+ full recharge cycles.

He likes Enphase with its additional microinverters to supplement the Enphase microinverters he would use on the solar panels.

Our insiders’ advice: LFP, for sure. Get an expandable battery system that allows you to start at 5Kw and go to 15kW.

Our advice: Make sure any battery is not exposed to weather and regularly check its performance statistics.

Finally, look very carefully at so-called managed battery plans, where a company takes control of your battery in return for a fixed monthly power fee. Users have reported having no energy storage left during peak times or outages. You need to control your energy.

EV charging options

Most rooftop solar systems are single-phase and can support a 7kW/32A/DC EV charging point, which is used to attach an EV charger from $1500-$2000 plus install costs. A 7kW is the largest you can get with a single phase and will fill a 70kW EV battery in under 10 hours – vastly faster than a 240V trickle charge outlet.

The Catch22 is that you need one that uses the rooftop solar system app rather than its app, as you don’t have total control over energy use. For example, a charger will take all available power. An overall app may allocate that from solar panels, batteries, or even the off-peak grid for the most economical charge.

Pitfalls to watch out for

We have covered most of the issues, but the main message is that cheap systems have more problems than those specified to meet your needs. They are at a higher risk of breakdown and don’t last the distance. You should look for 25 years of panel quality and 15+ years of battery quality.

You need to change your perception from how much you get back in feed-in tariffs to how much reliable, 24/7 energy can be created and how best to use that energy for a return on investment.

The most significant risk is a double-edged sword. Will power prices keep increasing, or will we get control of the baseload with coal/gas/nuclear (resulting in energy price decreases) and use renewables where possible?

My gamble is that the 49% increase over the last few years will continue unabated.

Rooftop Solar Part 3 coming in January 2025

I will tell you what I ended up buying and why.

• Panel (I went for Viridian PIPV for so many reasons)
• Inverter (I went for Enphase microinverters for safety and efficiency)
• Battery (I went for 2 x 5kWh Enphase batteries)
• EV charger (7kW point installed but no charger selected yet)
• App software (Enphase)
• Photos of the build process
• Any unforeseen issues
• Real cost and why I spent more
• Preliminary results
• More reader feedback

Rooftop Solar Part 4 con in June 2025

• Real-world results
• Did it meet my expectations?
• Observations

Disclaimer: CyberShack has received no money or discounts from the brands mentioned in the Rooftop Solar series. The reviewer has paid the full recommended pricing, and the series reflects CyberShack readers, Life and Technology listeners and his experiences.

We encourage you to tell us your experiences by emailing [email protected].

Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2, Rooftop Solar Part 2

Brought to you by CyberShack.com.au