🌿 Wednesday Wisdom

Solar Panel Monitoring — What I Track Monthly

We check our solar app every day. Here’s what we’re actually looking for — and what a year of data taught us about solar in Wisconsin.


The Daily Check

Every morning, one of us opens the Enphase app to see how the panels did the day before.

“Did they do well?” sounds vague, but after a year with the system, you develop a feel for it. A sunny summer day should produce 100–130 kWh. A December day might give you 5. A cloudy day in April lands somewhere in the 20–40 kWh range. You start to calibrate to your system, your location, your weather.

When the number is way off from what the conditions should have delivered, that’s when you start asking questions.


Our Setup

We have a 25.2 kW array — 56 VSUN Solar 450W bi-facial panels with Enphase IQ8A microinverters and an Enphase IQ Envoy for monitoring. The system went live August 13, 2024, so we have our first full calendar year (2025) of data to work with.

The array spans four sections of our standing seam metal roof:

  • Roof 1 — 12 panels (bottom left)
  • Roof 2 — 15 panels (bottom right)
  • Array 3 — main array (center)
  • Roof 4 — 3 panels (top)

Why does that matter? Because Enphase monitors at the panel level. If one panel or one section is underperforming, you can see it.


What Enphase Shows You

The Enphase Enlighten app gives you several views:

System overview — Today’s production, current power output (live), and a graph of production through the day. This is what we check daily.

Energy — Production vs. consumption vs. grid import/export. This is where you see whether you’re running on solar or drawing from the grid.

Devices — Individual panel performance. Each of the 56 microinverters reports separately. This is how you catch a panel that’s producing at half capacity.

Reports — Monthly and annual summaries you can export as CSV. I’ve exported monthly reports for every month of 2025.

The daily view is the one most people use. The devices view is the one you want to check if something looks wrong.


What “Did Well” Actually Means

Here are the benchmarks I’ve developed for our 25.2 kW system in southwest Wisconsin:

Conditions Expected Daily Production
Full sun, summer (May–Aug) 100–130 kWh
Partly cloudy, summer 50–80 kWh
Overcast, summer 20–40 kWh
Full sun, shoulder season (Mar–Apr, Sep–Oct) 50–80 kWh
Full sun, winter (Nov–Feb) 15–30 kWh
Cloudy/snow-covered, winter 0–5 kWh

Our annual daily average is 58 kWh. But averages are misleading — the real story is the gap between summer and winter.


The Seasonal Reality

This is the number that surprises people: summer produces 3.8x more than winter.

Our 2025 actual monthly production:

Month Production Peak Day Capability
January 951 kWh 9.75 kW
February 844 kWh 13.4 kW
March 2,070 kWh 17.0 kW
April 2,240 kWh 18.3 kW
May 2,890 kWh 19.3 kW
June 2,440 kWh 18.3 kW
July 2,990 kWh 19.1 kW
August 2,390 kWh 17.5 kW
September 1,920 kWh 16.8 kW
October 1,420 kWh 13.3 kW
November 857 kWh 10.0 kW
December 264 kWh 6.38 kW
Total 21.3 MWh

July was our best month (2.99 MWh). December was our worst (264 kWh) — the solar cells spent much of December under snow or behind thick clouds. Some days in December, we produced nearly nothing.

The seasonal swing isn’t a problem — it’s just how solar works at latitude 44°N. Net metering is what makes the math work: summer surplus flows to the grid as credits, and those credits offset winter imports at the full retail rate.


What the Data Shows (If You Look)

Enphase exports monthly CSV reports and tracks your production against a baseline estimate for your system size and location. I haven’t built a formal monthly review habit yet — but the data is there when I want it.

What’s worth knowing: a single bad day is almost always weather. A month that’s consistently 15–20% below baseline is worth investigating — possibly shading from new growth, a failing microinverter, or snow sitting on panels longer than expected. The Enphase app will flag anomalies, but only if you’re looking.


Spotting Problems Early

Enphase’s panel-level monitoring is one of the biggest advantages of microinverter systems over string inverters.

On a string inverter system, all your panels are wired together — one underperforming panel drags down the whole string, and it’s hard to know which one is the problem. With Enphase IQ8A microinverters, each panel has its own inverter and reports independently.

What to watch for in the Devices view:

  • One panel producing 30–50% less than its neighbors — possible shading issue, debris, or failing microinverter
  • All panels in one roof section underperforming — wiring issue or something specific to that section (like a snow drift that lingers)
  • Production dropping mid-day on a clear day — check for shade from nearby trees or objects at that sun angle

We haven’t had a microinverter failure yet. But I know what it would look like when it happens.


The Numbers That Actually Matter

After a full year, here’s what 21.3 MWh of solar production means in practice:

  • 60% of our annual household energy needs covered by solar (we consumed 35.7 MWh total, including EV charging)
  • 11.5 MWh exported to the grid in summer (those become credits)
  • 14.4 MWh imported from the grid (primarily winter heating and EV charging)
  • Net grid cost: ~$2,045/year (14.4 MWh × $0.142/kWh)
  • Value of solar produced: ~$3,025/year (21.3 MWh × $0.142/kWh)
  • CO₂ reduction: 15.2 tons (per Enphase — based on your grid’s carbon intensity)

That CO₂ number puts it in perspective. Fifteen tons is roughly equivalent to not driving 37,000 miles in a gas car — or about a year of our combined EV mileage, if we were driving on gas instead.


Is This Worth the Time?

Checking the app takes 30 seconds. Doing a monthly review takes maybe five minutes with a spreadsheet.

Is it necessary? No. The system runs without intervention — you don’t have to monitor it for it to work. But knowing what your system produces and what’s normal for your climate means you’ll notice when something’s off. A failed microinverter that goes unnoticed for six months is real money.

We’ve also found it motivating. Seeing 130 kWh on a July afternoon — knowing you’ve generated more than twice what the house needs that day — is genuinely satisfying. Watching it dip to 8 kWh on a gray December day and knowing your summer surplus already covered it is reassuring.

The monitoring doesn’t change what the panels do. But it makes you feel connected to the system in a way that makes the investment feel real.


Quick Reference

Our System:

  • 56 VSUN Solar 450W panels, Enphase IQ8A microinverters
  • Monitoring: Enphase Enlighten app + IQ Envoy
  • Grid-tied with net metering (Xcel Energy, $0.142/kWh)

2025 Production Summary:

Metric Value
Annual production 21.3 MWh
Best month July (2.99 MWh)
Worst month December (264 kWh)
Summer/winter ratio 3.8×
Solar offset 60% of household use

Daily Production Benchmarks (25 kW system, SW Wisconsin):

Season Good Day Bad Day
Summer (Jun–Aug) 100–130 kWh 15–30 kWh
Shoulder (Mar–May, Sep–Oct) 50–80 kWh 10–25 kWh
Winter (Nov–Feb) 15–30 kWh 0–5 kWh


The app doesn’t do anything for you — the panels run whether you check or not. But 30 seconds a day turns a black box on your roof into something you actually understand. And understanding your system is the first step toward optimizing it.