SolarMark Blog · Local Monitoring

You bought the panels. Why are you renting the data?

August 24, 2026

Every solar inverter measures its own production every second. It has to; that's how it works. The question is what happens to those numbers next. In the standard setup, they travel to the manufacturer's servers, and you view them through an app that connects to those servers. That arrangement is why monitoring can be degraded, paywalled, or shut off entirely: you're not reading your inverter, you're reading their copy of it.

The last few years showed how fragile that is. Monitoring portals have outages. Companies get acquired, go bankrupt, or move features behind subscriptions. SunPower's customers watched their free monitoring become a paid one after the company's bankruptcy. Customers of closed installers found their monitoring accounts belonged to a company that no longer exists.

The part nobody tells you: the data is already on your network

Most residential inverters support Modbus TCP, a standard local protocol that serves live data directly over your home network. Major brands like SolarEdge, SMA, and Fronius implement it through an open standard called SunSpec. It's the same data the cloud app shows you, read straight from the source, with no account and nothing to subscribe to. It even updates faster: local polling can refresh every few seconds, where cloud portals typically batch data into 5 or 15 minute intervals.

Local monitoring means an app on your phone talks straight to the inverter over Wi-Fi. Nothing leaves your house. Nobody can discontinue it, raise its price, or have an outage on your behalf.

What it takes, honestly

1. A one-time settings change. Every brand ships with Modbus switched off. On Fronius and many SMA systems you can enable it yourself in the inverter's web interface. On SolarEdge it takes an installer with SetApp access. Our brand guides cover the exact steps: SolarEdge, SMA, Fronius, Sungrow.
2. A reserved IP address for the inverter in your router app. Ten minutes, once.
3. Compatible hardware. This is the honest limit: microinverter systems like Enphase, and gateway-based systems like SunPower's, don't expose standard local Modbus. If that's your roof, local monitoring apps can't help today.

For remote access away from home, cloud apps have an inherent advantage; the local answer is a VPN like WireGuard or Tailscale, which keeps the no-middleman property but takes one evening of setup.

Who this is for

If you check your production daily, care where your data lives, own a system whose installer or portal has burned you before, or just refuse to pay rent on your own roof's numbers, local monitoring fits. If you glance at a chart once a month and your free cloud app works fine, you don't need to change anything, and we'd rather say so than pretend otherwise.

SolarMark is one way to do it: a one-time purchase app for Android and iOS that polls your inverter locally, keeps history on your phone, and has a free 14-day trial so you can confirm your hardware connects before paying anything. However you do it, the principle stands: the data starts on your equipment. It can stay there.