If you’ve had solar power for a few years and found your bills are getting uncomfortably high, you could probably use more solar yield. However, as we’ll explain, it’s not as simple as plonking more panels on the roof.
Older systems we’ve already covered. This discussion focuses on systems that may have been installed in the ‘teens.
Unfortunately, expanding middle-aged solar power systems can render a lot of good inverters and solar panels obsolete.
Professionally I’m disappointed, because it was hard graft putting this gear on the roof. And it’s infuriating because while second-hand solar panels might be redeployable, for worthy causes in developing nations, the world doesn’t need more e-waste made up of perfectly functional inverters.
ABB/Aurora, Fronius IG were cut from a better cloth. Aerosharp were a knock off SMA but the rest of this bin is full of crap.
Practicalities Of Adding Panels
There are about as many scenarios as there are houses to install them on. Whether it’s microinverters, expanding an old system, a new inverter beside an old one, there can be lots to consider. We’ll follow up with more specific details in another article.
Points To Remember If Adding New Solar Panels to an existing system
- Most modern solar panels have crept up to 13 or 14amp output, so older inverters may clip or struggle for efficiency
- Mixing old panels and new inverters may void warranties
- Microinverters may have been sold as expandable, but mixing old models with newer series may not be feasible
- Expanded systems aren’t eligible for legacy premium feed-in tariff but the economic payback can still be attractive
Why You May Need To Junk Your Inverter
Considering the electricity distribution networks in Australia were designed for big steam engines as hubs with spokes of cascading losses, careful management is critical to keep the lights shining when, increasingly the thing is running in reverse. Managing thousands of little solar generators takes some smarts so we should be proud there’s Australians developing the technology.
The upshot? New solar must offer dynamic export control so networks can throttle output when conditions are too perfect. Sadly, most old solar inverters can’t be curtailed, so networks are insisting on new ones.
Kaco Powador, the “german quality” that evaporated alongside an Omnik. Standards are much improved since this junk was new.
So when you upgrade, your network will insist that you use an inverter that adheres to the absolute latest standards. It would be nice to have new systems working beside old ones, but there’s no grandfather clause sadly1
The good news is that a new inverter + new solar panels are classed as a whole new system that attracts new STC incentives. So while the rebate falls 7% each year, panel prices are falling too. New glass on the roof is still basically free.
Why You Might Need To Junk Your Solar Panels
If you get a new inverter, a new serial number means you can claim new STC credits, so it’s probably best to install a completely new system with new compliance and a full suite of features, including warranty.
I have seen first hand the retrospective regret of installers and customers when they’ve found hidden problems while moving old solar panels. Be it cracks in the backsheet or broken hardware from obsolete framing, the heartache is real.
Consider Adding Monitoring First
If you’ve got a big bill and a budget to replace your solar, there are significant benefits to the latest technology. Knowledge is power, so consider a switchboard upgrade with monitoring like CatchControl even before you add solar.
Having proper data is brilliant for visualising consumption, tailoring your retail deal and knowing what size solar you’ll need. If you’re considering a battery, make sure you have surplus energy or a clever TOU tariff to charge it. As a consumption meter, the CatchControl becomes an integral part of your new system.
The award for brutalist design and minimalist styling goes to Latronics. Monitoring is nothing but four LEDs and a simple counter for kWh. This one still goes but I’m waiting for CatchPower to release a 3phase monitoring device.
Get Rid Of Roof Top Isolators
It’s seldom policed, but network rules mandate your solar power system should be inspected by an electrician every 5 years. Where it should be enforced is for the dreaded RTI. The opportunity to remove these fire prone DC switches is one I wouldn’t miss.
How To Legally Ignore Inverter Limits
If you want freedom from the rules and more capacity than the networks will allow, the solar inverter standard AS4777 now defines an inverter that’s an “independent” supply from a conventional grid-tied inverter. A Selectronic SP-Pro inverter configured correctly means you can have a large independent system and treat the grid with contempt.
The SP Pro forms a gateway where, although you can’t export, the grid instead becomes your cheap, reliable backup generator.2 Then you’re free to have almost unlimited solar and battery downstream of it.
This customer wanted 40kW of solar on a single phase connection. Selectronic means he can thumb his nose at his local network inverter limits.
There’s No Time Like The Present
If you have the itch to do more with solar, click here to see what rules apply. With models designed for whole home backup, hybrid technology is genuinely powerful now, so it pays to get sound advice. Gather up your recent bills, download your utility meter data; then get an expert to visit your place and assess the place from the roof down. Click here to get scratching.
Footnotes
- If you have a Fronius SnapInverter, a simple firmware update offers standards compliance. Add a Fronius Gen24 with more solar and viola! the job is done. Your ten year warranty remains intact. ↩
- Generators are both unreliable and essential for long winter weeks; plus expensive to buy and maintain. As we say in the off grid industry, generators make the phone ring ↩
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