I was thinking about putting solar panels on my house in Milan, but I don't want to do a complete electrical system overhaul. What do I need to do to connect them? Is it enough to just add an inverter or do I have to change the panel and wiring no matter what?
The reality is that many older household electrical systems, especially in Milan where there are lots of homes from the 70s-80s, have a major problem: the cables aren't sized to handle the extra load that a solar installation generates. It's not just about the inverter. If you connect directly to the existing panel without checking the cable gauge and the meter capacity, you risk creating bottlenecks that reduce your panels' efficiency and can even cause overheating.
What you really need is a proper technical assessment before you start. An electrician with solar experience will look at the actual condition of your cables, where your panel is located, and your power contract capacity. If everything's up to code, maybe just swapping the inverter is enough. But often you'll need to at least upgrade some internal connections and install a new protection device dedicated to the panels, so they don't "talk" directly to the rest of your system. It's not a complete rewire, but it's not something simple to DIY either.
It depends on your current system's condition. If you've got a decent electrical panel and your wiring is in good shape, you can usually just add the inverter and wire the panels through your existing panel without tearing everything apart. But an electrician still needs to check whether your system can handle the power output (based on your meter's amperage rating and cable capacity) and whether it meets current regulations for solar installations - you might need minor upgrades like a surge protector or a dedicated breaker, not necessarily a full rewire. The good news is you almost never have to replace the whole panel; worst case, you just add modules to the existing one.
It's not quite true that just adding an inverter is enough if your system is old, but there's something a lot of people overlook: before you do anything, get a licensed electrician to do a thermal imaging inspection of your panel and wiring - it usually doesn't cost much and it'll tell you exactly what you can safely leave as is and what actually needs work. That way you dodge expensive surprises and might even find out that some parts are fine while others really do need to be touched.
The critical thing that nobody really mentions is the grid connection: if you truly want to "not touch anything," theoretically you could install a completely off-grid system with batteries, but then you lose the entire economic advantage of panels, because batteries cost a fortune and don't last long. If instead you want to take advantage of solar like most people do (feed power back into the grid, reduce your bill), the electrical panel has to be modified, it's not optional, it's required by regulations.
What you can actually do without major hassles: keep your existing system and put the inverter on a new dedicated line that runs straight from the meter. It's not ideal from a design perspective, but if your panel's already maxed out, you can get by without redoing the whole thing. But you'll still need protective devices installed (surge arrestors, differential switches for the solar system) and a qualified professional who knows how to make this kind of compliant connection. In Milan especially, systems from the '70s and '80s often still have aluminum wiring or undersized cable sections, so before you start work, get a serious professional inspection of your panel.
The first thing you should really check is whether your contract with the grid distributor allows installation without prior notification, because Milan and the metropolitan area have pretty strict regulations on this. If you decide not to touch anything in your existing system, it's technically possible with a hybrid inverter and storage batteries, but then you're not feeding energy back into the grid and it only makes sense if you want pure self-consumption, otherwise you're cutting into the financial returns on your investment quite a bit. The check I'd really suggest is a preliminary consultation with a licensed electrician who can give it to you straight about whether your system can handle it without any work, because doing jobs badly costs more than doing them right from the start.
If your system already has good grounding and a modern meter, you can often just add the inverter and make the necessary connections without touching the main panel. What nobody ever tells you is that first you should ask your energy provider whether your line can handle the panels: some areas have limits on how much power you can feed back into the grid, and finding that out after you've already spent money is a kick in the teeth. A practical hack is to start with a 3-4 kW system without batteries (way cheaper and simpler) and see how it goes for a year; if it works and you don't have any issues, you can expand it later if you want.
An inverter alone isn't enough - the guys are telling you the right things but leaving stuff out: what you really need is a grid connection permit (if you want to sell excess energy) or a hybrid system with battery storage, and in both cases the Agenzia delle Dogane e dei Monopoli requires specific inspections of the system. If your panel is from the 70s-80s, you'll most likely need at least to add a dedicated section with DC breakers and protections for the panels - you can't just cram everything into the old panel and hope for the best. The only way to actually touch things as little as possible is to install a completely off-grid system with battery storage, but then you're giving up on making money from the grid and anyway a qualified electrician has to sign off on the project.
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