Germany has a million of these. What California can and can't copy

The German numbers

Germany calls them Balkonkraftwerke — balcony power plants. Registration is compulsory in a national database, the Marktstammdatenregister, which means the numbers are unusually good for a consumer product.

Two and a half percent of households in four years, for a product almost nobody had heard of before it started. That's the number worth holding onto.

What made it work

One registration, no approval. You fill in a form in a national database. Nobody assesses it, nobody visits, nobody has to agree. It took Germany a while to get there — the rules were simplified progressively — and simplification tracked adoption closely.

A cap low enough to be uncontroversial. 800 watts on a 230-volt supply is a small enough injection that the safety argument mostly evaporates. California's 1,200 watts on 120 volts is a comparable current.

Retail distribution. This is the big one. You buy a Balkonkraftwerk at IKEA, or a supermarket, or a hardware chain, in a box, off a shelf, for a price you can see. Once a product is on that shelf it stops being a project and becomes a purchase.

A product standard. DIN VDE V 0126-95, effective December 2025, is Germany's dedicated product safety standard for these — the equivalent of what UL 3700 is here. Note the direction: mass adoption came first, the dedicated standard followed.

Renters are the market. Germany has a very high rental share and strong tenant protections, including law making it harder for landlords to refuse. That's the piece California most conspicuously didn't copy.

What California copied

The registration model. SB 868 lets a utility require a simple online registration — address, make, model, size — and specifically bars approval requirements and fees. That's the German approach.

The wattage cap, adjusted for a 120-volt grid.

A safety standard, though California put it first rather than last. Germany got to a million devices and then wrote a dedicated standard. California is requiring the standard before the market exists, which is more cautious and is precisely why the catalogue is thin. What UL 3700 is.

What California didn't copy

Export compensation. German plug-in solar owners feed surplus into the grid and, depending on their arrangement, receive something for it or at least aren't penalised. SB 868 is silent, which means surplus is worth zero.

This is a bigger deal than it sounds and it's why our advice keeps circling back to daytime consumption and batteries. A German household exporting at midday loses less than a Californian one does.

Tenant protection. German law gives tenants a meaningfully stronger position on this. SB 868 doesn't touch landlords or HOAs at all. In a state where 44 percent of households rent and Orange County is 82 percent HOA-governed, that's the binding constraint. The permission problem.

Retail. Senator Wiener has talked about people picking these up at Home Depot, Costco or IKEA. That isn't where the market is today. Until it is, buying one requires finding a website, understanding a certification, and choosing mounting hardware — which is three more decisions than most people will make.

What it suggests for California

If Germany's 2.5 percent in four years translated to California's roughly 6 million renter households, that's around 150,000 devices — and that's before homeowners.

We'd temper that in both directions. California electricity is more expensive, which helps. California has no export payment and much weaker tenant protection, which hurts. And Germany's adoption was accelerated by an energy price shock in 2022 that California hasn't had in the same form.

Somewhere in the tens of thousands over the first few years seems plausible for California renters. Which is a real market, and a small one, and both of those things are worth saying out loud.