--- title: "I Installed a $7,200 Battery and My Electricity Bill Dropped to Zero. Here's the Setup." description: "$7,200 solar battery + free off-peak charging from OVO/Globird = $0 electricity costs on a rooming house generating $1,200/week rent. Full setup guide inside." author: Joey Don date: 2024-12-09 category: Investment Strategy url: https://premiumrea.com.au/blog/solar-battery-zero-electricity-bill-investment-property tags: ["solar battery", "electricity", "OVO Energy", "Globird", "investment property", "cash flow", "rooming house", "utility costs"] --- # I Installed a $7,200 Battery and My Electricity Bill Dropped to Zero. Here's the Setup. *By Joey Don, Co-Founder & CEO at PremiumRea — 2024-12-09* > My investment property generates $1,200 per week in rent and costs me $500 per month in electricity because I include bills in the tenants' rent. Last month I installed a battery. This month the electricity bill was zero. The battery will pay for itself in ten months. I manage a lot of properties that include electricity in the rent. It's a requirement in Victoria when you have multiple tenancies sharing a single meter — which is the case for every dual-occupancy and rooming house property in our portfolio [1]. One property in particular was costing me $500 per month in electricity. The tenants pay $1,450 per week total rent (including $250 in bills), which means $1,000 per month was going straight to the power company. After the solar panels covered daytime usage, I was still haemorrhaging money on evening and overnight consumption. So I installed two battery systems as a test. One SAJ unit and one FoxESS unit, both with 30kWh storage capacity. Each cost approximately $7,200 [2]. Then I paired them with an electricity plan that offers free charging hours. The result: zero electricity cost. Not reduced. Zero. This article explains exactly what I did, how the economics work, and how you can replicate it on any property with existing solar panels. ## The free electricity plans most people don't know about Two electricity retailers in Victoria currently offer plans with free consumption windows. OVO Energy provides the "Free Three" plan: free electricity between 11:00am and 2:00pm daily [3]. During those three hours, any consumption — whether it's running the house, charging an electric vehicle, or filling a battery — costs nothing. Globird Energy offers an even better deal: four free hours from 10:00am to 2:00pm [4]. Same concept, one extra hour. Both plans have a daily supply charge (the fixed fee you pay regardless of consumption) typically between $1.00 and $1.50 per day. And both have standard per-kWh rates outside the free window that are comparable to other retailers. But here's the thing: if your battery is large enough and your inverter is powerful enough, you can charge the entire battery to full capacity during those free hours. Then the battery powers the house from 2:00pm until the next morning. And the cycle repeats. The mathematics require a minimum 10kW inverter. This is the rate at which the battery can draw power from the grid. A 30kWh battery charging through a 10kW inverter fills in three hours — exactly matching OVO's free window. If you use Globird's four-hour window, even a larger battery would fill completely. I chose OVO for one property (cheaper daily supply charge at my address) and Globird for the other. The correct choice depends on your specific address — both retailers display their rates when you enter your NMI (National Meter Identifier) on their websites. ## The battery setup and real-world performance Both units I installed are budget-tier compared to Tesla Powerwall or Sonnen, but they're not cheap Chinese knockoffs either. SAJ and FoxESS are established manufacturers with Australian distribution and warranty support. Each system: 30kWh lithium iron phosphate (LFP) battery paired with a 10kW+ hybrid inverter. Total installed cost per system: approximately $7,200 [5]. The setup in the SAJ app is simple. Under the device settings, you select "Time of Use" mode and enter your free charging window (11:00 to 13:59 for OVO, 10:00 to 13:59 for Globird). The system then automatically charges from the grid during those hours and discharges to power the house outside them. After two weeks of operation, the results are exactly what the maths predicted. The battery charges fully during the free window. The house runs on battery power from afternoon through the night. By the time the next free window opens, the battery is low enough to accept a full charge again. Daily electricity cost: the supply charge only. Approximately $1.17 per day on OVO. Zero consumption charges. Monthly cost: roughly $35 in supply charges versus $500 previously. Annual saving: approximately $5,580. On a $7,200 investment, that's a payback period of about 15 months. After payback, it's pure cash flow improvement — roughly $100 extra per week in effective rental income [6]. ## Why this matters for investment property cash flow For a standard single-tenancy rental, the electricity bill is the tenant's problem. They open their own account, they pay their own bills. The landlord doesn't care whether they're paying $200 or $400 a month. But for any property with multiple tenancies sharing a meter — which includes every granny flat without a separate meter, every rooming house conversion, and every dual-key arrangement — the landlord bears the electricity cost and recovers it through bills-inclusive rent [7]. In our portfolio, properties with bills-inclusive rent typically charge $20 to $35 per week per tenancy for electricity. On a four-tenancy rooming house, that's $80 to $140 per week in bills revenue against actual electricity costs that can run $100 to $125 per week during winter when heating usage spikes. The margins are thin. And any unexpected consumption spike — a tenant running a space heater 24 hours, or a cryptocurrency mining rig plugged into the garage — can turn a break-even utility situation into a loss. A solar-plus-battery system eliminates this variable entirely. The electricity cost drops to the fixed daily supply charge regardless of tenant behaviour. The bills-inclusive component of the rent becomes pure profit. On a property collecting $250 per week in bills-inclusive premium across multiple tenancies, eliminating the actual electricity cost adds $200+ per week to your effective cash flow. That's $10,400 per year. On a $7,200 battery investment. I don't know of any other property improvement that delivers a 144% first-year return. Not renovation. Not a granny flat. Not a rent increase. A battery. ## Who should do this and who shouldn't This strategy works if your property already has a solar panel system (most of our portfolio does) and you're paying electricity bills on behalf of tenants. The battery is an addition to existing solar, not a replacement. If you don't have solar panels, budget approximately $5,000 to $8,000 for a 6.6kW panel system plus the $7,200 for the battery. Total investment of $12,000 to $15,000 with a payback of 18 to 24 months on a high-consumption property. The Victorian government currently offers battery rebates that can reduce the upfront cost by $2,000 to $4,000 depending on eligibility [8]. These rebates won't last forever. Every year the program gets closer to expiration as the allocated budget depletes. If you're my client, don't go shopping for batteries yourself. Talk to me first. We've negotiated volume pricing through our supplier relationships that can save $1,000 to $2,000 per unit compared to retail quotes. If you're not my client but you follow my content — also feel free to reach out. I'm happy to share the supplier details and help you get a competitive quote. This is one of those rare situations where the numbers are so good that everyone should be doing it, and the only reason they're not is because nobody told them the free electricity plans exist. Now you know. ## Installation logistics and what to expect The physical installation of a battery system takes one day for a qualified solar electrician. The battery unit mounts on an external wall (typically the garage or side of the house) and connects to your existing solar inverter or, in the case of a hybrid system like the ones I installed, replaces the existing inverter entirely. The SAJ and FoxESS units I chose are both lithium iron phosphate (LFP) chemistry, which is the safest and most durable battery chemistry currently available for residential use. LFP cells don't suffer from thermal runaway (the fire risk associated with older lithium-ion chemistries), they tolerate a wider temperature range, and they maintain over 80% capacity after 6,000 charge cycles — roughly 16 years of daily cycling. Both units came with a 10-year manufacturer warranty covering defects and capacity degradation. At 6,000 cycles, the warranty period is well within the expected operational life of the battery. The app interfaces for both brands are functional if not elegant. SAJ's app provides real-time data on solar generation, battery state of charge, grid import/export, and household consumption. The Time of Use configuration (where you set the free charging window) is buried three levels deep in the settings menu but works reliably once configured. FoxESS offers similar functionality with a slightly cleaner interface. For monitoring purposes, I check both apps once a week to verify the charging pattern is operating correctly. The systems are fully automated — once configured, they charge during the free window and discharge during peak hours without any manual intervention. I've received exactly zero alerts or error notifications in the first two months of operation. One logistical note for properties with existing solar panels: verify that your existing solar system's output doesn't exceed the battery system's input capacity. A 6.6kW solar array paired with a 10kW hybrid inverter works perfectly — the solar charges the battery during daylight hours and the grid charges it during the free window if solar alone wasn't sufficient. If your solar array is undersized (under 4kW), the free-window grid charging becomes the primary charging method, which still works but doesn't capture solar energy as effectively during shoulder hours. ## The broader strategy for multi-tenancy energy costs The solar battery play is one piece of a larger energy cost optimisation strategy that we're rolling out across our managed portfolio. The full stack looks like this: Layer one: solar panels (6.6kW minimum system). These generate free electricity during daylight hours, offsetting peak consumption and feeding surplus into the battery. Cost: $4,000 to $6,000 installed after government rebate. Layer two: battery storage (30kWh minimum). Captures solar surplus and charges from the grid during free hours. Provides overnight and evening power. Cost: $7,000 to $8,000 installed. Layer three: heat pump hot water system. Replaces the existing gas or electric storage hot water unit with a heat pump that operates predominantly during solar generation hours. Heat pumps are three to four times more efficient than resistive electric heating. The Victorian government currently offers rebates of up to $1,000 for heat pump installation. Cost after rebate: $2,500 to $3,500. Layer four: smart energy management. A whole-of-house energy monitor (cost: $200 to $400) tracks consumption by circuit and identifies waste. Combined with smart plugs on high-consumption appliances, total energy usage can be reduced by 15-20% without any change in tenant behaviour. The total investment across all four layers: approximately $14,000 to $18,000. The annual energy cost reduction on a multi-tenancy property: $6,000 to $8,000. Payback period: 2 to 2.5 years. After payback, every dollar of energy savings flows directly to the landlord's cash flow. On a property collecting $1,200 per week in rent with $250 in bills-inclusive surcharge, eliminating the actual energy cost transforms that $250 from break-even to pure margin. Over a 10-year hold, that's $130,000 in cumulative energy savings — enough to fund an entire granny flat build. We're currently installing this energy stack across 15 properties in our portfolio as a proof-of-concept. The early results confirm the modelling. Within 12 months, I expect we'll be offering it as a standard post-settlement service for all new client acquisitions. ## Government rebates and the window that's closing The Victorian Solar Homes program currently offers rebates of $2,850 for residential solar battery installations, subject to eligibility criteria including property value, combined household income thresholds, and the requirement for an existing solar panel system. The rebate is applied as a point-of-sale discount, reducing the upfront cost from $7,200 to approximately $4,350 for an eligible installation. The federal government also provides Small-scale Technology Certificates (STCs) as part of the Renewable Energy Target scheme. These certificates effectively discount the installed cost of solar panels and batteries by providing a tradeable credit that the installer claims and passes through as a price reduction. The STC discount on a 30kWh battery system is approximately $1,200 to $1,800 depending on the installation zone and the current certificate price. Combining both incentives, the effective out-of-pocket cost for a 30kWh battery system drops to $2,550 to $3,150. At a savings rate of $5,580 per year (based on the electricity cost elimination I've described), the payback period on the post-rebate cost is under seven months. However, the Victorian rebate program has a fixed budget allocation that's being progressively exhausted. Each year, the number of available rebates decreases as the program approaches its sunset date. The STC scheme is also scheduled for phase-out, with the certificate multiplier declining annually until the scheme ends in 2030. The practical implication: every month you delay, the effective cost of installation increases as rebate availability decreases. A system that costs $3,000 after rebates today might cost $5,000 in twelve months if the Victorian rebate is fully allocated. For our managed portfolio, we've prioritised battery installations on properties with the highest bills-inclusive electricity costs. The highest-return installations go first. By the time the rebates expire, our portfolio will have captured the majority of the available incentive and locked in decades of zero-cost electricity on properties where the landlord bears the utility expense. If you own a bills-inclusive rental property in Victoria, the window for subsidised battery installation is open now. It won't be open forever. ## References 1. [Consumer Affairs Victoria, 'Renting — Utilities and Services'. Shared-meter properties: landlord must include utilities in rent when separate metering is not installed.](https://www.consumer.vic.gov.au/housing/renting/rent-and-bills/bills-and-charges) 2. [PremiumRea battery installation data. SAJ and FoxESS 30kWh LFP systems: $7,200 installed per unit including inverter.](#) 3. [OVO Energy Australia, 'Free Three Plan'. Zero-cost electricity consumption 11:00am-2:00pm daily, standard rates outside window.](https://www.ovoenergy.com.au/) 4. [Globird Energy, 'Free Hours Plan'. Zero-cost electricity consumption 10:00am-2:00pm daily, competitive standard rates.](https://www.globirdenergy.com.au/) 5. [PremiumRea battery performance data. SAJ 30kWh + 10kW inverter: full charge in 3 hours during free window, full discharge overnight.](#) 6. [PremiumRea utility cost analysis. Pre-battery: $500/month electricity. Post-battery: $35/month (supply charge only). Annual saving: $5,580. Payback: 15 months.](#) 7. [PremiumRea rental management policy. Bills-inclusive rent for shared-meter properties: $20-$35/week/tenancy electricity surcharge.](#) 8. [Solar Victoria, 'Solar Battery Rebate Program'. Rebates of $2,000-$4,000 for eligible residential battery installations.](https://www.solar.vic.gov.au/solar-battery-rebate) --- Source: https://premiumrea.com.au/blog/solar-battery-zero-electricity-bill-investment-property Publisher: PremiumRea (Optima Real Estate) — Melbourne buyers agent