Investing in a residential dwelling battery and photo voltaic system is usually thought-about possible provided that the payback falls inside the battery guarantee interval – usually 10 years. In accordance with this bloke, that’s simply doable.
Josh Mylne is, amongst different issues, a dad, a scientist, and an power nerd. He has an unhealthy habit to Excel spreadsheets, solely maybe surpassed by SQ’s Ronald Brakels.
He’s extracted an obscene quantity of information from his numerous apps and residential power payments and reckons his solar energy, battery, heat-pump and induction cooking set-up is on its option to paying for itself in lower than 10 years. Manner much less.
Josh lives in my dwelling state of WA, so I assumed I’d go round and have a chat – or as his spouse calls it, “nerd out collectively”.
Unwholesome Dependancy
The Excel habit and power nerdism began round 2005 when Josh and his household moved from the UK again to Australia. They have been skint, so as a result of budgetary constraints, out got here the Excel spreadsheet to information their funds.
They continued being a one-car household and used bicycles as a lot as sensible. Quick ahead to the COVID-19 pandemic and the decarbonisation journey started in earnest.
On Go The Photo voltaic Panels
In November 2020, that they had rooftop solar energy put in. The system consisted of 19 x Q.MAXX-G2 Qcells 350W photo voltaic panels (6.65kW whole), and a Huawei SUN2000 single part 5kw hybrid inverter.
Putting in Josh’s preliminary Q.MAXX-G2 Qcells 350W photo voltaic panels. Picture: Josh Mylne
Josh says: “I knew nothing about photo voltaic on the time. This video on YouTube from the Photo voltaic 101 webpage is 25 minutes and it explains all the things. After watching it, I used the SolarQuotes web site to rearrange three quotes and the information at Photo voltaic 101 to work out what was high quality gear.”1
After the photo voltaic panels have been put in, the electrical energy payments dropped by about $950 p.a. However that wasn’t sufficient for Josh. He’s not a giant fan of provide fees or the miserly feed-in tariff provided by Synergy in WA. He turned a internet exporter of electrical energy, however that didn’t replicate in energy payments as a result of distinction in import tariff (30c per kWh) and feed-in tariff (2.5c to 10c per kWh), and the aforementioned provide cost ($1.07/day). Grrr. Extra work to do.
Josh’s electrical energy payments from February 2015 to November 2022. See the large dip in November 2020 when the photo voltaic panels went on, then once more in November 2021 with the battery + extra photo voltaic. Picture: Josh Mylne
See Josh’s electrical energy utilization graph under in comparison with the payments above. He turned a internet exporter in November 2020 nevertheless it didn’t replicate in his electrical energy payments. Not glad Jan.
Josh’s electrical energy utilization from February 2015 to November 2022, displaying his internet exports after the solar energy system set up. Picture: Josh Mylne
Getting Off The Gasoline
The purpose was to decarbonise their lives as a lot as potential, so getting off the gasoline was a precedence. Concurrently the photo voltaic panels went on, the gasoline scorching water system was changed with an iStore 270L warmth pump.
Gasoline utilization instantly plummeted by 95%. The invoice, nevertheless, dropped by solely about 80% – nonetheless a powerful saving of $750 p.a. This was as soon as once more due to the despised provide cost. A kitchen renovation in July 2022 supplied an excuse to ditch gasoline altogether once they put in an induction cooktop, offering additional financial savings.
Having no gasoline invoice now saves them $900 p.a. The one gasoline at their place now comes out of a bottle once they hearth up the BBQ.
Josh’s gasoline utilization chart under reveals an enormous drop in November 2020 with the brand new warmth pump, which disappears in August 2022 when the gasoline was cut-off. Picture: Josh Mylne
What’s The Warmth Pump All About?
I’ll let Josh inform you:
“The warmth pump is good. It really works like an inside-out fridge; the cool air being dissipated and the warmth being launched into coils heating the water. It has numerous modes, however we’ve got ours set to come back on at 11 am and to not cycle after 5 pm, which suggests it’s normally utilizing photo voltaic power to warmth the water.”
Out with the outdated gasoline boiler and in with the brand new iStore 270L warmth pump. Picture: Josh Mylne
“We’ve not run out of scorching water but, regardless of having three teenage boys. By utilizing photo voltaic power after which storing the power within the water as warmth, in methods it’s appearing like a battery. It solely attracts about 1.2 to 1.6kW whereas it’s working. It runs normally for about 90 minutes every day and works higher the hotter the air round it’s.”
House Battery + Extra Photo voltaic Energy
Not content material with the financial savings already achieved, the household determined (or perhaps Josh determined) to buy a house battery in November 2021. On the identical time the Huawei Luna 10 kWh battery2 was put in, they threw one other 7 x 350W photo voltaic panels on the roof, bringing it to a complete of 9.1kW of photo voltaic capability.
Joyful household: Huawei SUN2000 single part 5kw hybrid inverter, Huawei Luna 10 kWh battery, and Smappee EV Wall Charger. Picture: Josh Mylne
Josh should have been bouncing off the partitions in pleasure on the considered increasing his Excel spreadsheet to incorporate the battery. He’s now labored out they’ve change into 93% self-sufficient for power. To place it one other means, solely 7% of the electrical energy they use comes from the grid, averaged over the entire 12 months.
He says that the battery will get them all through the evening 310 days per 12 months (84.9%), though it’s virtually unattainable to have a day that’s 100% self-sufficient as any spike of use that goes above 5kW must be lined by the grid.
“After one full 12 months with the battery, I analyzed how typically the battery will get you all via the evening to the following day (see the graph under). Out of the entire 12 months, 341 days (93.4%) made it previous 9 pm, 334 days (91.5%) made it previous midnight, 320 days (87.7%) it obtained previous 4 am, and 310 days (84.9%) it made at all through all evening to the following day with no grid draw in any respect.”
I have to admit at first look I struggled to ‘get’ the graph under, which reveals the flexibility of Josh’s battery to see them via the evening with out grid energy, over a interval of 12 months. The inexperienced isn’t really a Christmas tree, however the knowledge. The white bars (which appear to be the info) are, in reality, displaying the place the battery didn’t make the gap, and the grid kicks in. When you stare at it lengthy sufficient it’ll make sense.
Josh’s ‘Battery By means of The Evening’ graph. Picture: Josh Mylne
You possibly can see the heatwaves in late summer season the place just a few days in a row the battery was drained by 9 pm because of the air conditioner. Winter had the occasional tremendous overcast/ wet day when the battery didn’t absolutely cost, as you virtually at all times see single white bars.
Sizzling tip for WA photo voltaic patrons:
Josh’s photo voltaic, battery and inverter are DC-coupled, giving him probably extra energy to cost the battery than an AC coupled system would. Because the battery is related to the DC facet of the hybrid inverter, its enter isn’t restricted by the 5 kW nominal inverter score, and so can reap the benefits of all of the unclipped energy accessible from the photo voltaic array to cost the battery.
This works notably properly in programs the place the DNSP guidelines restrict single-phase inverter sizes to five kW (WA), and a bonus in battery programs the place panel capability is greater than 133% of the inverter score. Josh’s system ticks all of the above containers – Western Energy inverter restrict: 5 kW (single part), Josh’s photo voltaic: 9.1 kW, Josh’s inverter: 5 kW. This might arguably be a major think about trimming down the payback time for a house battery.
Out With The Diesel And In With The EV
In September 2022, the household turned proud house owners of a model new BYD Atto 3 electrical car. I’m jealous as hell. This EV has (type of) changed their growing old 2011 diesel Holden Captiva which had clocked over 230,000km. They’re hanging on to the Captiva for now, as the 2 oldest sons are actually driving age.
BYD Atto 3 electrical car. Picture: The Pushed
Previous to the children rising up, the gasoline invoice was $3,000 p.a. Sure, there’s a spreadsheet for that too (graph under). Gasoline prices then spiked to $4,500 p.a. with the brand new drivers, after which because the EV buy has dropped all the way down to $30/ quarter up to now.
Josh’s gasoline prices since December 2014. We’ll see how that pans out because the arrival of his fancy new EV in September 2022. Wanting good up to now. Picture: Josh Mylne
Josh says the Atto 3 is a pleasant automobile to drive, with a variety of 480km on a full tank cost.
“The EV will get pushed about 250 km every week. I commute by bike, however my spouse leaves for work earlier than the photo voltaic kicks in and will get dwelling after sundown, so we cost the EV on weekends. Generally through the week, if I’m working from dwelling, I’ll drop my spouse at work and go away the EV at dwelling charging. Now we have a Smappee EV Wall Charger that has a sensible mode that makes use of solely surplus photo voltaic to cost the automobile.”
The Backside Line
So fairly footage and graphs apart, after extracting knowledge from Josh’s spreadsheets, he reckons the mixed solar energy plus battery funding can pay again in 6.4 years. It is a conservative estimate as a result of the price of the warmth pump and induction cooktop may arguably be unnoticed of the equation because the gasoline home equipment have been on the finish of their life. That might convey the payback all the way down to 4.9 years.
The underside line – Josh’s mixed photo voltaic + battery payback estimate. Picture: SolarQuotes
The EV isn’t included as a result of he solely has about three months of information. I’m certain that in about 9 months we’ll see a brand new Excel spreadsheet with a full-blown gasoline financial savings evaluation, together with the complete price of possession and depreciation comparability between his EV and the outdated Holden Captiva.
There’s yet another factor Josh wish to say about that.
“The entire payback equation modifications in case you can energy your automobile with surplus photo voltaic, which we do. A tank of diesel prices $110 and will get us 400 km. With the EV, a 60 kWh full cost will get us 480 km, and prices actually 2 or 3 {dollars}. That’s all I get if I feed 60 kWh into the grid.”
Like many solar energy system house owners and folks within the business, Josh didn’t begin his decarbonisation mission to save cash. That’s simply an added bonus.
“I went photo voltaic not simply to save cash, however to make much less carbon dioxide myself in addition to, in a tiny means, assist hasten the decline of wasteful, polluting, and more and more costly fossil fuels.”
Thanks for doing a number of the heavy lifting, Josh. I’m 100% with you on that. You possibly can comply with the remainder of Josh’s journey because it evolves on his personal weblog proper right here.
