How to Monitor Your Solar Production (App Guide)

The single most useful number to watch is your daily kWh production against a seasonal baseline. A healthy, well-sited 5kW system in most of Aotearoa produces roughly 18 to 25 kWh on a clear summer day and 6 to 12 kWh on a clear winter day, which lines up with NIWA's solar irradiance data of about 1,400 to 1,600 kWh of sunlight per kW of panels per year across most of the country. Your inverter app shows you this in real time. If your numbers sit well below that range on a genuinely clear day, something is off, and the app is where you catch it first. Learn to read three screens (today's output, the live power curve, and the monthly totals) and you will spot a fault weeks before it shows up as a nasty power bill.

Most people install solar, glance at the app for a fortnight, then never open it again. That is a quiet waste. A panel string can drop offline, an optimiser can fail, a bird can nest under an array, and you would never know until the savings stopped landing. The app is your early warning system, and it costs you nothing but five minutes a week.

What the app is actually telling you

Every grid-tied system in New Zealand comes with monitoring built into the inverter. The brand of inverter determines the app you use:

• Fronius (Austrian, very common in NZ): Solar.web, available as an app and a browser dashboard.
• SMA: Sunny Portal and the SMA Energy app.
• GoodWe: SEMS Portal and the GoodWe app.
• Sungrow: iSolarCloud.
• SolarEdge (panel-level optimisers): the mySolarEdge app, which shows production per panel.
• Enphase (microinverters): the Enlighten app, also panel-level.
• Tesla Powerwall: the Tesla app for battery and whole-home flow.

They all look slightly different, but they all show you the same core information. Once you understand the four readings below, you can read any of them.

1. Today's production (kWh)

This is total energy generated since midnight, measured in kilowatt-hours. It is the headline figure. Track it against what a clear day should produce for your system size and the season.

2. Current power (kW)

This is the instantaneous rate of generation right now. A 5kW system on a clear day around noon in summer should be pushing close to its inverter rating, often 4 to 5 kW. Cloud passes drop it in seconds. This number bounces around constantly and that is completely normal.

3. The daily power curve

This is the graph that teaches you the most. On a clear day it should look like a smooth bell curve: rising from sunrise, peaking around solar noon (roughly 1pm in summer with daylight saving), and tapering to zero at sunset. The shape is the diagnostic. Dips, plateaus, and chunks missing from one side of the curve tell you exactly where to look.

4. Self-consumption vs export

If your system has a consumption meter fitted (many do, some don't), the app splits your generation into what you used in the house and what you sent to the grid. This is the number that drives your actual savings, because power you use yourself is worth far more than power you export. We dig into why that gap matters so much when you are running the payback numbers in the cost and ROI calculator.

Build your baseline first, then everything else is easy

Here is the bit nobody tells you: a single day's number means almost nothing on its own. You cannot spot underperformance without a baseline. A "low" reading might just be a cloudy Tuesday.

Spend your first clear-sky week of ownership writing down, or screenshotting, the production on genuinely cloudless days. Do it again at the start of each season. Within a year you will have a personal benchmark: what your roof does on a clear summer day, an average autumn day, a clear frosty winter day in the south, and so on.

That seasonal swing is dramatic and it surprises people. Thanks to NIWA's sunshine-hour data, we know that the difference between the best and worst months is large everywhere, but it is brutal in the lower South Island. A system in Invercargill or Dunedin might produce four to five times more in December than in June. That is not a fault. That is the Earth's tilt doing its thing. If you do not know your baseline, you will panic in July for no reason.

What a clear-day baseline roughly looks like

Using NIWA irradiance figures, here is a rough guide for a well-installed, unshaded, north-facing 5kW system on a clear day. Your real numbers will vary with roof pitch, orientation, and exact location, which is exactly why you build your own baseline:

• Far North / Northland (high sun hours): summer 24 to 28 kWh, deep winter 8 to 12 kWh.
• Auckland / Waikato / Bay of Plenty: summer 22 to 26 kWh, deep winter 7 to 11 kWh.
• Wellington (good sun, but watch winter cloud and wind): summer 21 to 25 kWh, deep winter 6 to 10 kWh.
• Canterbury plains (clear, cold, excellent): summer 23 to 27 kWh, deep winter 7 to 11 kWh.
• Central Otago (cold air and clear winter skies are a genuine advantage): summer 24 to 28 kWh, deep winter 6 to 10 kWh, and panels love the cold.
• West Coast (the honest exception, real cloud problem): expect noticeably lower and more variable totals year-round.

A quirk worth knowing: cold, clear days produce excellent instantaneous power because solar panels are more efficient when cool. A frosty Central Otago morning with a low sun can have the panels punching above their weight per hour of sunlight, even though the total daily kWh is low because the day is short. So do not be fooled by a high midday power reading in winter; the short day still limits the total.

The red flags: what underperformance actually looks like in the app

Once your baseline is set, faults announce themselves. Here are the signals worth knowing, roughly in order of how often they crop up.

The whole day is down on a clear day

If today was cloudless and your total is well under your baseline (say, a third lower or worse), look for the obvious culprits first: dirt, dust, pollen, or bird mess on the panels, or new shading from a tree that has grown or a neighbour's extension. Pollen season and long dry spells in places like Canterbury and Hawke's Bay genuinely cut output. We cover what is worth cleaning (and what absolutely is not worth climbing onto your roof for) in our piece on cleaning and maintaining panels.

A flat top on the power curve (clipping)

If the bell curve has a flat plateau at the top, that is your inverter clipping: the panels are producing more than the inverter can convert, so it caps the output. A little of this on the brightest summer days is normal and even intentional in some system designs. But if you see heavy clipping for hours, your array may be oversized for your inverter, which means you paid for panels you are not fully using. Worth raising with your installer.

A clean "step" in the curve

A sudden vertical drop partway through the day, where output falls and stays lower, often points to one string going offline on a multi-string inverter, or a section of the array being shaded at a predictable time (a chimney, a pole, a tree). If the step happens at the same time every day, it is shading. If it is random, it is more likely a fault.

One panel reading low (SolarEdge and Enphase only)

This is the hidden advantage of panel-level systems. In the mySolarEdge or Enlighten app you can see each panel as a tile. One tile consistently darker or lower than its neighbours on a clear day means a failing optimiser, a failing microinverter, or a shaded or faulty panel. String inverters (Fronius, SMA, GoodWe, Sungrow) cannot show you this; they only see the string total. That is a real trade-off to understand, and it is worth knowing before you ever buy. If you are still at the quote stage, it is one of the things worth weighing up when you compare installers and system designs.

Zero production, mid-morning, clear sky

A flat zero line when the sun is clearly up is the one that needs attention today. Common causes: the inverter has tripped or faulted (check for an error code or red light on the unit), an AC isolator has been switched off, or the inverter has lost its grid connection. Many inverters will show a fault code in the app. Note it down; it is gold when you call your installer.

Gaps in the data

Sometimes the production is fine but the app shows gaps. That is usually just your Wi-Fi or internet dropping out, not a generation fault. The inverter keeps working and generating regardless; it just cannot phone home. Reconnect it to your home network and the data fills back in. The power was still being made.

A worked example: a 1960s weatherboard place in Mount Eden

Picture a 6kW system on a north-east-facing roof in Mount Eden, Auckland (Vector network). The owner built a baseline in their first summer: clear days landing around 28 to 32 kWh.

Come the following March, clear-sky totals quietly slipped to about 24 kWh. Not dramatic, easy to miss. But the owner checked the daily curve and saw a clean step appearing every afternoon from about 3pm. The morning half of the curve was perfect.

The culprit was a neighbour's poplar that had put on a season of growth and now clipped the north-east array late in the day. Nothing was broken. The fix was a quiet word over the fence and a trim. Without the app and the baseline, that owner would have lost a chunk of autumn and winter generation and blamed the weather.

That is the whole point. The app turns "my bill seems a bit high" into "my afternoon output is down 15% and here is exactly why."

Reading a battery in the app

If you have a battery (Tesla Powerwall, a Sungrow or GoodWe hybrid, or similar), the app adds a few flows worth understanding:

• State of charge (%): how full the battery is right now.
• Charging vs discharging: solar filling the battery during the day, the battery running the house at night.
• Power flow diagram: most battery apps show a live animated diagram of energy moving between panels, battery, house, and grid. It is genuinely useful for understanding your own habits.

A healthy daily pattern on a good day: solar charges the battery to full by early afternoon, exports the surplus, then the battery covers the evening peak. The red flag is a battery that never reaches full on clear days, or one whose usable capacity is visibly shrinking year on year beyond the gentle degradation the warranty allows. Battery degradation is normal and expected; a sudden capacity cliff is not.

One smart move many Kiwi households use: time-of-use plans from retailers like Octopus Energy NZ, Electric Kiwi, or Contact mean low-cost or free off-peak windows. The app helps you see whether your battery is being used to dodge the expensive peak periods or just cycling pointlessly. That insight alone can change which power plan you should be on.

The thing the installers don't tell you about monitoring

Here is the genuinely useful, rarely-mentioned bit. Your inverter app shows generation, but unless a separate consumption meter (a "smart meter" CT clamp) was fitted at install, it cannot show you what you actually used or saved.

Plenty of systems in New Zealand are installed without that consumption meter, because it adds a little cost and the sale closes fine without it. The result is an owner who can see they generated 22 kWh but has no idea how much of it they used in the house versus exported for a low buy-back rate. And the gap between those two is where nearly all your savings live, because self-consumed power offsets the full retail rate (often 30c-plus per kWh) while exported power earns the buy-back rate (frequently 7c to 17c, depending on your retailer).

If you are serious about understanding your savings, ask whether your system has a consumption meter, and if not, get one retrofitted. It is usually a modest job. The buy-back side of this equation deserves proper attention on its own, and we break down how the rates really stack up across retailers in our wider material; for the day-to-day, just know that the export number in your app is the lower-value number, and using more of your own power during daylight is almost always the better play.

How often should you actually look?

You do not need to babysit this. A sensible rhythm:

• Daily, for the first month, to learn what normal looks like and build your baseline.
• Weekly glance after that: open the app on the next clear day and sanity-check the total against your baseline.
• Set alerts if your app supports them (Fronius Solar.web, Enphase Enlighten and SolarEdge all can email or push you if the system stops reporting or faults). Turn these on. They do the watching for you.
• A proper monthly review: compare this month's total to the same month last year. Year-on-year is the truest test of whether your system is ageing gracefully.

Who can skip most of this

In the interest of honesty: if you have a small, simple, unshaded system with monitoring alerts switched on, you can mostly let the alerts do the work and check in monthly. You do not need to become obsessed. The detailed curve-reading matters most for larger systems, shaded or complex roofs, and anyone with a battery and a time-of-use plan where the savings genuinely hinge on behaviour.

And if your output has clearly dropped and you have worked through the obvious causes without an answer, do not keep guessing. We have a full troubleshooting walk-through for exactly that situation over here: why has my solar output dropped? If it turns out to be a hardware fault still under warranty, our guide to making a warranty claim in NZ walks you through it step by step. And for the bigger picture of living with a system well, our ownership and aftercare guide ties it all together.

Frequently Asked Questions

Why is my solar producing nothing right now when it's sunny?

Check the inverter itself first: a red or flashing light usually means a fault, and the app may show an error code. Other common causes are a tripped AC isolator switch or the inverter losing its grid connection. If the app simply shows a data gap rather than zero generation, it is almost always a Wi-Fi dropout and the system is still working fine.

What is a normal daily output for a 5kW system in New Zealand?

On a clear day, roughly 18 to 25 kWh in summer and 6 to 12 kWh in deep winter for a well-sited, north-facing system, based on NIWA irradiance data of around 1,400 to 1,600 kWh per kW per year across most of the country. Your own baseline matters more than any general figure, because pitch, orientation, and shading change everything.

Why does my output drop so much in winter?

Shorter days and a lower sun angle mean far less energy reaches the panels. The seasonal swing is large everywhere and most extreme in the lower South Island, where June output can be a fraction of December's. This is completely normal and not a fault. Solar will not zero your winter bill, and any claim that it does should be treated with suspicion.

Can I see how much each individual panel is producing?

Only if you have a panel-level system: SolarEdge (with optimisers) shows each panel in the mySolarEdge app, and Enphase microinverters show each panel in the Enlighten app. Standard string inverters like Fronius, SMA, GoodWe and Sungrow only report the total per string, not per panel. This is a genuine difference worth understanding before you buy.

What does a flat line on top of my production graph mean?

That is clipping: your panels are generating more than the inverter can convert, so it caps the output at its rated limit. A small amount on the brightest summer days is normal and sometimes intended by design. Hours of heavy clipping suggests your array may be oversized for your inverter, which is worth raising with your installer.

Does the app show me how much money I'm saving?

Not directly, and often not at all unless a consumption meter was fitted at install. The inverter app shows generation; to see what you used in the house versus exported to the grid you need that extra meter. Since self-consumed power is worth far more than exported power at typical buy-back rates, this is the number that actually drives your savings, so it is well worth retrofitting if you don't have it.

How often should I check my solar app?

Daily for the first month to learn your baseline, then a weekly glance on a clear day plus a monthly year-on-year comparison is plenty. Better still, switch on the app's fault and offline alerts (Fronius, Enphase and SolarEdge all offer them) so the system tells you when something is wrong.

My battery never charges to 100%, is something wrong?

On a clear day with surplus generation, a healthy battery should reach full. If it consistently falls short on good days, or its usable capacity drops noticeably year on year beyond the gentle degradation your warranty allows, flag it with your installer. Gradual, slow degradation is expected; a sudden capacity drop is not.

The Bottom Line

Your inverter app is the lowest-cost insurance you own. Learn the four core readings, build a seasonal baseline on clear days, and switch on the fault alerts. After that, a weekly glance and a monthly year-on-year check will catch almost anything that goes wrong, often weeks before it shows up on a power bill.

The one upgrade worth chasing if you don't have it is a consumption meter, so the app shows what you actually used, not just what you made. That is where your real savings story lives. From there, keeping the panels clean and knowing what to do when output dips will keep your system honest for its full twenty-five-year-plus life.