Batteries
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Battery ready solar inverters in Australia

We won't win any friends from many others in the solar industry but the biggest lie told by solar sales reps is that the inverter they are selling is "battery ready".

Almost every inverter sold today, unless it is a hybrid model, is not capable of connecting to a battery, not now, not ever. Pictured below is the underneath of the Fronius Primo and Huawei FusionHome. The Huawei is a hybrid and you can see the battery connectors, the Fronius is not. Where would the batteries go?

 

The reason why these solar companies and their sales reps might be able to successfully plead their case if dragged into court by the ACCC or sued by an irate customer, is that whilst the inverter is, and never will be, battery ready, there are a couple of ways to add batteries to any home, at significant additional cost.

 

Retro fitting batteries to a non hybrid inverter
Let's say you have a Fronius Primo inverter and the time has come to connect batteries.

Your shopping list will be as follows:
1. Good quality 10 kWh battery (e.g. LG Chem), cost approx $7,000
2. "Battery interface" (AC or DC coupled options available) that the battery connects to.

In reality, this 'interface' is another inverter or DC converter (another box on the wall if you like), and in most cases your existing inverter is entirely ignored and just carries on dealing with panel power conversion. The current starting price for a 'small' 2.5kW interface is around $1500 installed, rising to a more typical $2000 for a 5kW unit. The manufacturer who is leading the field in these retro fit products is Goodwe, but SMA and Enphase have small and pretty expensive units too. More products are on the way for sure as the potential, even in Australia alone with 2 million non hybrid solar installations is mouth wateringly good.

 

Adding batteries to a hybrid inverter
Hybrids are ready to go for batteries. Just hook up their inverter smart meter and off you go.

To give you some sort of an idea on cost. If you compare a good regular non hybrid from any of the top Asian brands (Delta, Goodwe, Growatt, Sungrow, Zeversolar) then you will be paying about $650 to $1000 more for a hybrid. However if you compare a good hybrid like Huawei or Goodwe with a European made inverter from ABB or Fronius, then the price difference is minimal...maybe $50 or so.

 

What is a non hybrid inverter?
Pretty much everything currently out there past and present is NOT a hybrid inverter so the above solution applies, exactly the same as for the Fronius example if you bought an SMA SunnyBoy, Zeversolar, Goodwe, Delta, Sungrow, Growatt, SolarEdge, JFY, ABB, etc

 

What hybrid inverters are currently available in Australia?
Just to really confuse the matter, quite a few manufacturers have some hybrids in their range of products. It's like saying that Toyota have a bunch of regular petrol and diesel models, but they also have some all electric vehicle models too.

The entire Huawei FusionHome range are hybrids from 2kW to 5kW.
Goodwe have four hybrids from a range of 20 inverters.

Delta and Sungrow have one or two hybrids, also from a pretty large range.

SolarEdge have one hybrid (StorEdge) and one non hybrid range (HD Wave) but the non hybrid can be made into a hybrid by adding a SESTI interface costing about $1700.

Fronius adapted their three phase 5kW SYMO product to work with the original Tesla battery, but now that has been withdrawn, the only battery it connects to is their own which costs double what anything else does. It also made the inverter into a 'single tracker' so unless all your panels face the exact same way, forget it...oh and it costs about $1500 more than the regular SYMO.

 

Emergency Circuits

Most people consider batteries for "load shifting" where surplus solar power is stored in batteries during the day to be used in the house at night. Remember though that the battery has a constant companion of the grid, so if you turn on something that needs more power than the battery can provide (e.g. oven, kettle, microwave, air con) then the grid will step in and make up the difference. So what happens when there is no grid...a power failure?

In this case, if you turned on a device that needed more power than the battery can deliver it's likely that the battery will trip, and then you will have NO power at all. The solution to this is an emergency circuit which is a feature offered by some, but not all hybrids. Goodwe EM and ES hybrids both have emergency circuits (10A or 2.3kW and 20A or 4.6kW respectively), SolarEdge Storedge has a 22A circuit (5kW) but SolarEdge HD Wave model does not. Huawei are releasing one soon. Creating a brand new 10A or ~20A circuit of low power critical loads can mean a significant re-wire of your home and is unlikely to be cheap.

 

Warranty

The nice thing about Huawei hybrid is they give a 10 year product warranty. So your entire system is covered for 10 years. With the regular inverter, even if it comes with a 10 year warranty as some do, the box that is running the batteries typically has a 5 year warranty.

Size matters

The amount of space needed to accomodate an inverter and battery system can be very significant so hybrids again come out on top. Our favourite, Huawei, is just 35cm square. Half the size of a Fronius Primo (65cm x 43 cm), which would then need an extra box (35 cm x 42 cm) . Then you need the battery (45cm x 48cm)