Selectronic SP PRO: My Favourite Powerwall Alternative

If you are looking for the ultimate solar and battery system, whether on or off the grid, then in my opinion you should build it around the Selectronic SP PRO inverter. It is in a class of its own. I mean that in more ways than one, but you’ll have to indulge me while I explain. My personal favourite battery inverter, the Selectronic SP PRO is an Australian-made grid forming inverter that can equally be used as a grid hybrid or stand-alone supply.

Better than a Tesla Powerwall

The performance you can take for granted from an SP Pro simply isn’t supported by a Powerwall. It’s not a soft-roader SUV that might get you through a sticky situation, it’s an army tank that ploughs through unaffected.

The tech support is brilliant, absolutely nonpareil, and the inverters themselves are the last word in reliability. They’re very flexible, conservatively rated and capable (with 240% surge capacity) to the point you need not segregate the switchboard into essential and superfluous, because they will run the whole house, seamlessly. This is the technology that keeps the lights on for the Royal Flying Doctor Service at Innaminka.

More Expensive Than A Powerwall

The catch is the price. The last one I installed (with 8kW of solar, a Fronius solar inverter and 14kWh of battery) was about $30k by the time the shouting died down. Incidentally, between March and December, monitoring shows that customer has exported 1802kWh and consumed 1548kWh with just seventeen kWh imported from the grid.

Compatible With Lots Of Batteries

Because of the nominal 48-volt input, they can have a dozen different types of battery, in small or huge capacities, and different chemistries depending on your preferences. For this writeup I have selected the new Selectronic Select Cell 13.44kWh Lithium Iron Phosphate Batteries.

The SP PRO can be DC-Coupled

This post is part of our series on hybrid solar inverters as Tesla Powerwall alternatives. A hybrid inverter will have solar panels and a battery both connected and managed simultaneously by one box.

Wheras the Selectronic Pro – known as a battery inverter – can also have the DC output of solar panels charging  straight into the battery. You simply add a ‘MPPT Solar Charge Controller’ (and a current shunt) then your solar is available to the SP PRO via the battery input.

It’s a very flexible approach to managing a diverse hybrid system and I recommend the superb Australian made AERL solar regulators to complete this setup.

It means you can DC Couple your solar and get all the benefits of DC coupling I talked about in my hybrid inverter post – the best being it allows significantly more solar to be installed than may otherwise be allowed by your local electricity network.

The SP Pro Is Often AC Coupled

There are also many options to connect AC-coupled solar inverters  which will charge the battery, run your house or export to the grid, but unlike a one box hybrid, Selectronic makes it easy to integrate black start capability or an auto-start generator.

The SP Pro Can Be A Single Phase Battery Inverter

If you just want to retrofit a battery to an existing solar panel array and single phase inverter. It can do that (with full backup – of course).

Three SP Pros Can Back Up A Three Phase Solar Inverter

One problem with 3 phase solar inverters is that they are hard to use with battery backup if you want to keep the solar running when the grid goes down. If you have an ‘Selectronic Certified’ compatible solar inverter, three SP-Pros can handle this task admirably. It won’t be cheap though…

Load Control Included

There are programmable outputs to manage energy with a mind-boggling array of priorities i.e. controlling a hot water service according to solar yield, battery state of charge, time of day or grid quality while simultaneously charging or discharging batteries according to TOU grid pricing.

All that control will involve lots of wires, and proper system integration, so a good installer will put thought into the design and cable management:

The Best Off Grid Inverter In The World?

Despite being a great option for grid-connected hybrid solar systems, the core market for the SP Pro has always been off-gridders. Finn reckons they are the best off-grid inverters in the world, and I concur.

[embedded content]

One Drawback Of The Sp Pro: No Grid Export

The only drawback I have to mention is that the SP PRO has literally been put into its own class on the CEC-approved inverters website. It’s an inherent feature of the heavy-duty transformer topology that the latest AS4777.2 rules will prevent you from exporting energy to the grid from the battery. They’re capable, but the rules simply won’t allow it. You can, of course, export solar from the attached AC-coupled grid-connect inverters, but the battery can’t be used for virtual power plant applications, unfortunately.

However, there is a benefit. If your local grid is prone to brownouts, or SAPN are cranking up the voltage to keep a lid on everyone’s solar exports, your SP PRO will have none of it. It will simply island you from the problems outside and you can continue to use your solar and battery until either the grid returns to normal or you want to start a generator.

Conclusion: I bloody love the SP Pro

The Selectronic SP PRO stands out as a powerful and reliable option if you want a high-performance grid-connected hybrid or off-grid solar energy system that offers unmatched reliability, flexibility, and excellent tech support. While its price tag may be steep, the features, specs, reliability and build quality make it an investment worth considering if you prioritise long-term energy independence and resilience.

With options to DC-couple or AC-couple, load control capabilities, and compatibility with a variety of battery chemistries, the SP PRO truly sets itself apart from other hybrid inverters. Although it does not support grid export from the battery due to Australian electrical regulations, its ability to island your home during grid issues is a significant advantage.

Overall, the Selectronic SP PRO is a top-tier choice that can provide dependable energy supply in any situation, and paired with a good battery like the Select Cell is a worthy contender as a Powerwall alternative.

Selectronic SP PRO: Technical Specs

• Nominal capacity: 5kW
• Surge rating: 12kW – 30sec,  8.7kW – 1min,  7kW – 30min.
• Solar capacity: 15kW PV solar
  10kW AC coupled nominal
  (Virtually unlimited additional capacity via DC coupling)
• Inverter Warranty: 10 years
• PV current ratings: 18a nominal – 36a short circuit
  12a nominal – 24a short circuit (dependant on inverter chosen)
• Solar Inverter Warranty:  5 + 5 years (Fronius)
• Battery: Select Cell 48V 13.44kWh Lithium Iron Phosphate
• Usable Capacity: 13.44 kWh
• Warranty: 8 years product – 60% retained capacity after 10 years – 35.6MWh throughput
• Throughput limit @ 1 full cycle per day:  7.25 years
• Approx retail: $6580 inveter +  $14260 battery + $2732 solar inverter plus installation
• $-per-usable-kWh: $1753
• $-per-warranted-kWh :$0.66 @ 1 cycle per day / $0.33 @ 2 cycles per day
• Three-Phase option available using three SP PROs chained together. Parallel specifications available to 240kW

Original Source: https://www.solarquotes.com.au/blog/selectronic-sp-pro/