A Buderim homeowner’s power bill for the three months to late April came to $904. She already had solar on the roof, which is the part that bothered her. The system was doing something, but not enough of it, and not at the times of day when it counted.
That works out to around ten dollars a day for a house that was supposed to be making its own power. It is the most common reason people call me, and it is worth walking through what we did about it.
Before we quoted anything
I had a quick look at the roof using aerial imagery before heading out, which I do on every job. It tells me what space there is to work with and where the shading is likely to sit.
Then I attended site and went through the existing system, the switchboard, and how the household actually uses power across the day. That last part matters more than most people expect. Two homes with the same roof can need very different systems depending on who is home during the day.
I also ask what is coming. An EV, a pool, ducted air conditioning. It is far easier to size for it now than to come back and add it later.
Repair or replace?
This is the question I get asked most, and there is no single answer to it. An older system can keep producing for years, so it is not really about whether it still works. It is whether it is still the right system for the house.
Sometimes a repair is the sensible call and I will say so. Here, a bill like that told the story. The roof was not generating enough, and what it did generate was going out to the grid during the day and being bought back at a higher rate at night. On top of that, the existing main switchboard was not built to carry a bigger system with storage. We could have worked around all of it, but she would have spent good money on a compromise.
Three options, not one
I do not hand people a single number and leave them to it. This customer got several system sizes to consider, along with a costing on an alternative product range that would have brought the total down, so she could see the trade-off for herself rather than take my word for it.
We landed on the design below because it suited the way the house actually runs, not because it was the biggest one on the list.
The new solar panels and battery
Twenty-nine solar panels went on, which comes to close to 13.8kW on the roof, with a 10kW inverter and a 25kWh battery. New DC was run as part of the work. The panels are Jinko and the inverter and battery are Sungrow.
One reason for choosing that battery in particular is that it can be expanded later, up to 40kWh, without having to add supporting hardware or redo what is already there. Storage needs tend to grow. A battery you can add to is worth more than a bigger one you cannot.
The logic of pairing an array that size with a battery that size is straightforward. Your roof makes most of its power in the middle of the day, which is usually when nobody is home to use it. Without storage, that surplus goes out to the grid for a small feed-in payment and you buy it back at a higher rate that evening. The battery keeps it at the house instead.
The switchboard upgrade
The other half of this job was a full main switchboard upgrade. It is not the interesting part, but there is no sense putting a new solar and battery system behind a board that was never designed to carry it.
This is why I ask for a photo of your switchboard before I quote anything. It greatly assists with the system design, and it means the price I give you accounts for the whole job rather than part of it.
Clearing the site
The old racking and rail came off the roof along with the panels, and all of it left with us, down to the offcuts. Redundant rail left bolted to a roof gives water somewhere to sit, so it is worth the extra hour to take it off properly while we are up there.
What a system like this may do for a household
A larger array captures more sun through the day, and a battery that size holds it for the evening rather than sending it out. Depending on how the home uses power, that could mean relying a good deal more on your own energy after dark and a good deal less on the grid.
What it actually does varies with your usage, roof orientation, shading and the weather, which is why I size a system to the house rather than to an average. I would not quote you a saving before I have seen your bills and your switchboard, and I would be careful of anyone who does.
Sunshine Coast solar, from Caloundra to Noosa
We are a local solar company based in Caloundra. We install and service solar across the Coast, including solar in Buderim, Caloundra, Mooloolaba, Maroochydore, Currimundi and Noosa.
If your bills look like that one and you have solar that is not keeping up, I am more than happy to talk through the different options and help find the one that best suits your requirements. Bring your last bill and a photo of your switchboard and we can have a proper conversation about it.
You can request a quote here, or please don’t hesitate to call or email.
Justin Zerna
Owner, AHJ Trade Services
0492 910 232
justin@ahjtrade.com.au
