What is PVOutput.org, and why solar owners keep coming back

If you have ever owned solar panels, there is a decent chance you have heard the name PVOutput drop in a forum thread, an installer's WhatsApp group, or somewhere on a Dutch- or English-speaking solar subreddit. It comes up a lot. And every time someone asks what it actually is, the answers are surprisingly varied: a logger, a community, a database, a graphing tool, a hobbyist project. They are all true, in a way, which is part of why explaining PVOutput is harder than it should be.

So let me try anyway, because once you understand what it is and what it isn't, the whole solar monitoring world gets easier to navigate.

A free service that has been quietly running for almost two decades

PVOutput.org is a website where owners of photovoltaic systems can upload, store, and visualise their solar production data. It was started in 2008 by Bankstown, an Australian developer who, like many early adopters, wanted a single place to see what his panels were doing without having to log into the inverter manufacturer's web portal every time. The project grew. Today it hosts hundreds of thousands of registered systems from every continent, and it remains free to use.

There is a paid donation tier that unlocks higher-resolution data and a few extras, but the bulk of what most users need is on the free side. You can register an account in a few minutes, define a system, and start uploading.

That said, the design is firmly from a different era of the web. The interface is dense, the menus are deep, and the documentation reads like it was written by someone who knew exactly what they meant and assumed you would too. None of this is a deal-breaker, but it does mean PVOutput rewards patience.

What it gives you

At its core, PVOutput stores time-series data. You upload how much energy your panels produced (in watt-hours), at what time, and optionally what your house consumed. The site turns those numbers into graphs, totals, comparisons against other users in your region, and a long-term archive that the inverter manufacturer's app almost certainly will not keep for you.

The features that keep people coming back tend to be the unglamorous ones:

• Long-term storage. Your inverter app might keep a year. PVOutput keeps everything you upload, indefinitely.
• Comparisons. You can see how your daily yield ranks against similar systems in your area, which is a useful sanity check after a cloudy week.
• Estimates. Each system can have an "expected" production curve based on its size and orientation, and PVOutput shows you the gap between expected and actual.
• An open API. This is the one most casual users never touch, but it is the reason third-party apps and scripts exist for PVOutput at all.

The data model is also more flexible than it first appears. You can log peak power, voltage, temperature, and various secondary metrics if your inverter exposes them. You can split a household installation into multiple "systems" if you have, say, a south-facing array and a separate east-west addition. None of this is required, but it is there.

Why people stick with it

The honest answer is that PVOutput hits a sweet spot. It is not your inverter's app, which means it is not going to disappear when the manufacturer rebrands or kills off a product line. It is not a paid SaaS service that charges you twenty euros a month for what amounts to a database. And it is run by someone who clearly cares about the platform, even if the visual design has not been a priority since around 2012.

There is also a community angle that is hard to overstate. The forums are quiet but generally helpful. When something goes wrong with a popular inverter brand, the discussion thread on PVOutput often pre-dates the manufacturer's official acknowledgement by several weeks.

The technical bit

Under the hood, PVOutput exposes a fairly straightforward HTTP API. Clients authenticate with two values, an API key and a system ID, and then send data to endpoints with names like addstatus.jsp, addoutput.jsp, and getoutput.jsp. The naming gives away the platform's age. There are a few quirks worth knowing about if you ever want to build something on top of it. The getoutput.jsp endpoint, for instance, has a hard cap of around 149 records per response regardless of the limit parameter you pass, so if you want to fetch a long history you need to chunk your requests in roughly 120-day windows. Rate limits are generous for individual use but exist, especially if you have not made a donation.

The data format is mostly CSV-style strings, dates as YYYYMMDD, energy in watt-hours, power in watts. There is no JSON support on most endpoints, which feels archaic in 2026 but does mean parsing is trivial in any language. The whole thing is documented at pvoutput.org/help, and while the docs are dense, they are accurate.

If you are the kind of person who wants to write your own scripts to push inverter data into PVOutput, or pull it out for a custom dashboard, the surface is small enough that a weekend is usually enough to get something working. This is, incidentally, why so many third-party apps exist for the platform. HelioPeak is one of them, focused on iOS, but there are others for Android and various web dashboards that scratch the same itch.

Should you bother?

If you have solar panels and your inverter only shows you data through a slow, ad-laden manufacturer app: yes, set up a PVOutput account. The initial configuration takes an hour or two, depending on your setup, and the data starts paying off the moment you have a few weeks to compare against. If you are someone who likes graphs, who wants to know whether last Tuesday was actually that bad or whether you just felt that way, you will find a use for it.

If, on the other hand, you bought solar to forget about it and let the energy bill take care of itself, PVOutput might be more than you need. That is also fine. Solar panels work just as well unmonitored.

But for the rest of us, the curious ones, the ones who occasionally stare at the inverter LED and wonder what it is doing today: PVOutput remains, after all these years, the easiest answer to "where do I keep my data?"