Energy Independence Calculator: How Much Could You Save?

How Much Could You Save With Solar, Battery & EV Charging?

Every Melbourne household’s energy profile is unique - your savings from solar panels, battery storage, and EV charging depend on your specific consumption patterns, roof characteristics, electricity tariff, and driving habits. This guide helps you estimate your potential savings and understand the factors that drive your return on investment.

For a precise, personalised assessment, call Carlin Co on 0432 632 346 - we’ll analyse your actual energy data and design a system optimised for your home.

Step 1: Understand Your Current Energy Costs

Electricity

Check your latest electricity bill for these key numbers:

• Daily consumption (kWh): The average Melbourne household uses 15-20 kWh/day. Find yours on your bill or in your retailer’s app.
• Electricity rate: Typically 28-38c/kWh for flat rates, or 35-55c/kWh peak / 18-25c/kWh off-peak for time-of-use tariffs in Victoria.
• Daily supply charge: Usually 90c-$1.30/day - you pay this regardless of consumption.
• Annual electricity cost: Most Melbourne households spend $1,800-$3,500/year on electricity.

Vehicle Fuel

If you’re considering an EV or already own one:

• Annual km driven: Average Australian drives approximately 12,000-15,000 km/year
• Petrol cost: At $1.80-$2.10/litre and 8-10L/100km for an average car, that’s $1,700-$3,150/year in fuel
• EV electricity cost: At 15-20 kWh/100km and 30c/kWh from the grid, an EV costs $540-$900/year to charge - or near zero if charging from solar

Step 2: Estimate Your Solar Savings

Solar Panel Savings Calculator

A solar system saves you money two ways: by reducing the electricity you buy from the grid (at 28-38c/kWh) and by earning feed-in credits for energy you export (at 4-7c/kWh). The more energy you use during daylight hours, the more you save.

Self-consumption rate is key. Without a battery, typical self-consumption is 30-50% of solar production. With a battery, it jumps to 70-90%.

Example - 6.6kW solar system in Melbourne:

• Annual production: ~9,000 kWh
• Without battery (40% self-consumption): 3,600 kWh self-consumed × 33c = $1,188 saved + 5,400 kWh exported × 5c = $270 feed-in = $1,458/year savings
• With battery (80% self-consumption): 7,200 kWh self-consumed × 33c = $2,376 saved + 1,800 kWh exported × 5c = $90 feed-in = $2,466/year savings

Step 3: Estimate Your Battery Savings

Battery Storage Value Calculator

A battery’s value comes from the difference between what you’d pay for grid electricity and what you’d receive for exporting that same solar energy. This is your “arbitrage value.”

Example - 13.5 kWh battery:

• Daily usable capacity (accounting for efficiency): ~12 kWh
• Value per kWh shifted from export to self-consumption: 33c (grid rate) – 5c (feed-in) = 28c
• If the battery cycles fully 300 days/year: 12 × 300 × $0.28 = $1,008/year additional savings

On a time-of-use tariff, the savings are even greater because you’re avoiding 45-55c/kWh peak rates rather than 28-33c flat rates.

For battery options and pricing, see our home battery storage guide and battery comparison.

Step 4: Estimate Your EV Charging Savings

EV vs Petrol Running Cost Comparison

The savings from switching to an EV - and particularly from charging it with solar - are often the most compelling part of a complete energy system.

Example - 15,000 km/year:

• Petrol car (8L/100km at $1.95/L): $2,340/year in fuel
• EV charging from grid (18 kWh/100km at 30c/kWh): $810/year - saving $1,530
• EV charging from solar (18 kWh/100km at ~0c): ~$0/year - saving $2,340

For charger costs and options, see our EV charger installation cost guide.

Step 5: Calculate Your Total Return

Complete System Example

Here’s a real-world example for a typical Melbourne household:

Current costs: $2,800/year electricity + $2,340/year petrol = $5,140/year total energy costs

System installed: 6.6kW solar ($6,500) + 13.5 kWh battery ($12,000) + EV charger ($2,500) = $21,000 total (before rebates)

After battery rebate ($2,950) and STCs (~$3,200): Net cost = approximately $14,850

Annual savings: $1,458 (solar) + $1,008 (battery) + $2,000 (EV solar charging vs petrol) = $4,466/year

Simple payback period: $14,850 ÷ $4,466 = 3.3 years

After payback, this system delivers $4,400+ per year in ongoing savings for 20+ years. That’s a total value exceeding $80,000 over the system’s lifetime.

Factors That Improve Your Return

• Higher electricity consumption → more savings from solar self-consumption
• Time-of-use tariff → battery arbitrage value increases significantly
• Higher petrol prices or more km driven → greater EV charging savings
• North-facing roof with no shading → maximum solar production
• Daytime energy use (pool, home office, hot water) → higher self-consumption without a battery

Get Your Personalised Assessment

These calculations provide useful estimates, but every home is different. Carlin Co provides detailed, personalised assessments using your actual energy data, roof measurements, and specific equipment pricing.

Call us on 0432 632 346 for an obligation-free assessment. As NETCC Approved Sellers, we’re committed to giving you transparent, honest advice - including telling you if a complete system isn’t the best option for your situation.

You can also use our EV charger cost calculator for a quick estimate on charger installation costs.