Adelaide solar quotes | Fronius vs Growatt

Hi, I’m super confused about which system to install. We use about 23 Kw/day during most of year but peak at 33/day or so during the winter peak. My husband works from home during the day (heating and cooling part of the year) and we also run an Airbnb with guests running heating/cooling over the hottest/coolest months - mostly morning and/or nights.

To complicate things we may not be in the house long term, but likely will hang on to it as a rental and charge the tenants something for power.

The below quotes are for a shade-free NW facing roof but we also have a small strip of mostly shade-free roof facing NE that may accomodate a few more panels (not quoted). Pitch: 15-30 Degrees, 2 Storey (build on side of hill so access via the single storey rear of house), Cement/Concrete Tile roof, Three Phase meter

Installer 1:
Quote 1: 6.6kW
20 x Hanwha QCELLS Q.MAXX 330w Monocrystalline (Q.MAXX 330W)
Growatt 5000TL3-S (3phase) 1
Total $4,600 (including rebate)

Quote 2: 10.89kW
33 x QCells Maxx 330W
1 x Fronius Symo 8.2kW
= $8,900 (Includes $6,300 rebate)

Option 3: 13.2kW
40 x QCells Maxx 330W
1 x Fronius Symo 10.0kW
= $9,900 (Includes $7,630 rebate)

Warranties for above options: Installation: 10 Years, Inverter Warranty: 5 + 5 Years, QCell Panels: 10 Years, Performance: approx 85% at 25 Years (estiamted from fact sheet)

Installer 2:
Option 4: 6.6KW
24 x Q-Cells Q.Power 275W panel
Fronius Primo 5 Inverter (1P) - incl. smart meter 1.00
= $4,200 (Includes estimated $3,800 rebate)

Installation: 7 Years, Fronius Inverter: 5 + 5 Years, QCell Panels Product: 12 Years, Performance: 83% at 25 Years


  1. Are these quotes reasonable? Should we go for the highest output cells? The tech sheets are so confusing I can’t compare the paybacks on each version to work out whether it’s worth spending more.
  2. As the NW roof is not shaded at all is it worth investing in the split cell technology or microinverters or is that overkill since the only shading will be passing clouds and the odd bird poop or leaf?
  3. I read about REC Alpha panels on a review site - claimed comparative price with the QCell, with highter output and longer warranty and supposed to work very well under high temperatures, (just had a 43+degree heatwave with temp on the driveway 50 degrees, so I’m guessing it was even hotter on our dark roof). Does anyone rate these over QCells or is the QCell good enough? Any other brands to consider? The Fronius seems to have ok reviews too and both installers use them but they may just get a better margin on them!
  4. Should we hedge and get a small system now with less feed-in tariff benefits and save the money for a second battery system a few years down the track when hopefully they are cheaper and even more efficient. Or or go with the bigger system, longer ROI but better longer term tariff rebates?
  5. If we go small system now, should we oversize the inverter upfront so we can add panels later - or does the technology move so fast this is unlikely to be any better than just getting a smaller one now and second smaller one or one big one when we add the extra cells?

Thanks in advance - any light shed on these dilemas would be much appreciated!!


A lot of questions here so ill try to keep it simple.

Yes the quotes are all very reasonable for a 2 story tiled roof using quality components. Fronius inverter is a great choice.

Installer 1, Option 2 seems to be the best choice for your amount of consumption. Due to the high winter loads you will need a larger system and 10 to 11kW will be about perfect. This could generate around 30kWh in winter and up to 65kW+ in summer (the excess in summer will give you more credits to offset nigh time usage).

Qcells are very good panels. The REC Alpha panels are slightly better but they are also more expensive. The REC Alpha panels which use HJC cells, will give a small increase in performance in summer (about 10%) but since you will already have a lot of excess generation in summer this won’t make much difference.

If you wanted to install a battery in the future you will need a large system to be able to both charge the battery and run the household loads during the day so it makes more sense to go with the larger 10kW system now. Batteries will create some extra savings (around 20%) but solar does the bulk of the savings (65% or more) and is far more economical.

Here’s some more information about the cost of batteries. I recommend installing solar first and deciding is it’s worth installing batteries in a few years time. You may find your solar alone will cover most of your bills.

Adelaide Solar Installers

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Thank you for your helpful feedback - much appreciated!