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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. More on hybrid inverters (that DO have battery connections) further down, but first let's look at the options for adding solar batteries when you have a non hybrid inverter.

Option 1  AC Coupled

A completely different additional inverter is connected to the switchboard. The battery connects to it, and there is a special additional meter that measures what power your home requires. SMA Sunnyboy storage is a good example of one of these products. It costs just under $2000 and then another $300 or so for installation. A cheaper alternative is the Goodwe SBP at $1650 for their 3.6kW and $2080 for their 5kW models, again with $300 installation.

Option 2  DC coupled

This time the extra box sits in-between the solar panels and the solar inverter. It intercepts the solar panel power and, again using a special smart meter, decides based on your household needs for power at that moment, whether to store your solar power in batteries or send it on through to the existing inverter to do its job as normal. The Goodwe BP is a 2.5kW example of one of these units and costs $1420, plus about $500 installation.

The benefits of buying a hybrid inverter

Option 1 and 2 above show how you can add an extra box to your solar installation, new or old, it makes no difference, and have battery storage. It has nothing to do with the inverter.

Hybrid inverters, like the Huawei pictured above, ARE totally ready to connect batteries. Just plug the battery into the underside of the inverter, wire up the smart meter to measure household power demands, and off you go.

Huawei have a 2kW, 3kW, 4.6kW and 5kW models. Goodwe have a 3kW and a couple of 5kW hybrids in their range, Delta have a 5kW hybrid as do Sungrow. All of these are single phase hybrid inverters. Some can be connected to 3 phase homes, others can't. It depends on the rules of your local electrical distribution company (e.g. Western Power, Ausgrid, CitiPower... etc). There are more hybrids available than listed above and more coming as people are rapidly moving away from traditional inverters.

Fronius have a 5kW 3 phase hybrid and Huawei have a 5kW 3 phase hybrid due out 1st qtr 2019 but you don't need them anyway. Single phase hybrid inverters can be connected to 3 phase homes without any problems at all.

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.

 

How much more do you pay for a hybrid?

Well, of course, with all that extra hardware and software inside compared to a regular inverter, it usually, but not always, does cost more but it is ALWAYS cheaper, simpler and neater to install a hybrid than buying a regular inverter and then adding any of the products described in Option 1 and 2 above.

Here are some comparitive prices

Huawei 3kW hybrid inverter $1560 (+ $150 for the smart meter)

Economy 3kW non hybrid inverter (Growatt, Goodwe, Sungrow) $900 to $1100

Premium 3kW non hybrid (Fronius Primo, SMA Sunnyboy) $1700

(Yes the Huawei hybrid is cheaper than the Fronius)

Huawei 5kW hybrid inverter $1750 (+$150 for the smart meter)

Economy 5kW non hybrid inverter (Growatt, Goodwe, Sungrow) $1100 to $1500

Premium 5kW non hybrid (Fronius Primo, SMA Sunnyboy) $2050

(Yes the Huawei hybrid is again cheaper than the Fronius)

Putting a complete battery ready system together

Fronius Primo ($2050) + Goodwe SBP ($1650) + install of SBP ($300) = $4,000

Huawei FusionHome hybrid ($1750) + Meter ($150) = $1900

Then add batteries to either.

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)