Energy Monitors: What They Can Tell You Before You Buy Solar
The single most useful thing an energy monitor tells you before you buy solar: when your household actually uses power. A solar system that generates most of its energy at noon while your house is empty is a much weaker investment than one sized for a household that runs appliances, heats water and charges devices during daylight hours. An energy monitor gives you that data before a solar installer does — and before you commit to a system size.
- A clamp-style energy monitor measures your whole home's usage in real time — not just one appliance.
- The key question it answers: how much power does your home use during daylight hours vs evenings?
- Households with high daytime usage get more value from solar. Households that are mostly empty during the day get less.
- A monitor also reveals hidden always-on loads that solar won't eliminate — standby devices drawing 50–200W continuously.
- Rooftop solar installation is fixed electrical work — design and installation require a licensed professional.
What a whole-home energy monitor actually measures
A clamp-style energy monitor installs on your switchboard (or clips around the mains cables) and measures the total power flowing in and out of your home continuously. Unlike a smart plug that measures one appliance, a whole-home monitor gives you:
- Total consumption by hour — when are you drawing the most from the grid?
- Always-on baseline — how much power is your home drawing at 3am when nothing is "on"?
- Peak demand periods — are your heavy loads morning, evening or spread across the day?
- If you already have solar: how much of your generation are you actually self-consuming vs exporting?
What you learn and how it changes the solar decision
Daytime usage pattern
Solar generates power when the sun shines. Energy consumed directly from the solar system (self-consumption) avoids grid import at full retail rate — typically 25–40c/kWh in most Australian states. Energy exported to the grid earns a feed-in tariff, typically 5–12c/kWh depending on your retailer and state.
The difference between self-consuming a kWh and exporting it is 15–30c per kWh. An energy monitor tells you how much of your generated solar you're likely to self-consume before you buy the system.
Households with high daytime usage (at-home workers, families with young children, retirees): solar pays faster, larger systems are more justifiable.
Households that are empty from 8am to 6pm: self-consumption will be low. A battery may be needed to capture solar for evening use — adding $8,000–$15,000 to the cost.
Always-on load discovery
Most households have 100–300W of always-on load — appliances and devices drawing power 24 hours a day: routers, old plasma TVs in standby, second fridges in the garage, pool pumps running at the wrong time, aquarium heaters.
An energy monitor reveals this baseline. Reducing always-on load before sizing solar can meaningfully change the recommended system size.
Peak demand timing
If your heaviest consumption happens in the evening — dishwasher, clothes dryer, oven, hot showers — solar without a battery cannot help with those loads directly. An energy monitor makes this visible before you buy.
Whole-home energy monitors worth considering
Whole-home energy monitors are a different product category to smart plugs. They measure the entire switchboard, not a single appliance. Most require installation by a licensed electrician or at minimum a competent homeowner familiar with switchboard safety. Check the product documentation before installation.
Emporia Vue 2 — a well-reviewed clamp-style monitor that measures up to 16 individual circuits alongside whole-home usage. App shows real-time and historical data. Popular with households wanting to understand which circuits (hot water, HVAC, kitchen) are driving the bill.
Sense Energy Monitor — machine-learning monitor that identifies individual appliances from their electrical signature over time. Takes a few weeks to learn the home's devices, then shows per-appliance usage without any smart plugs required. Premium price for genuinely useful per-appliance data at the whole-home level.
What an energy monitor cannot tell you
- Whether your roof is suitable for solar — that requires a site assessment by a licensed installer
- What system size is right — that depends on roof space, shading, orientation and local DNSPs
- Which installer to choose — get at least three quotes from Clean Energy Council accredited installers
- Whether a battery is worth it — that depends on your evening usage pattern and applicable rebates
The monitor gives you honest, household-specific data to bring into that conversation — not a replacement for professional advice.
Buy a whole-home energy monitor before getting solar quotes. Six weeks of usage data tells you your daytime consumption pattern, your always-on baseline, and whether a battery is likely to be necessary. It's a $150–$400 purchase that can change a $10,000+ decision.
See our Smart Home picks for energy monitors and smart plugs to start measuring before you commit to solar.