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Comment by blackoil | Hacker News Reader

Can they be used in apartment. We don't have roof space but can hang them vertically from balcony. Bi-facial won't work but what about mono-facial?

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Germany allows apartment tenants to hang panels on their balcony and feed 800W for their needs.

https://www.canarymedia.com/articles/solar/how-germany-outfi...

Utah also.

https://diysolarforum.com/threads/plug-in-balcony-solar-beco...

Assuming they can’t/won’t/shouldn’t back feed, that’s a lot easier to do in most of 240V single phase land. In US/Canada, you gotta pick the side of your building’s circuit that your continuous loads are usually on.

I don't understand what's different...

We're only talking ~800W 120V in most cases, so phase balancing is immaterial in this use case (in the context of balcony solar).

Edit: For larger installs (many vertical panels, >1kw), agree that balancing and a dedicated circuit is likely more optimal.

I mean, if you can't backfeed, you might have stuff "on" in your home, but your solar might not be on that side so it's not doing you any good.

What a bizarre situation. So if you have extra balcony space, you are not allowed to generate more than 800W for your own use?

Perhaps it is an arbitrary limit picked out of concern for weight and / or live energy in a place normally meant as living quarters. Too much of either on a balcony would be a hazard, especially if everyone with a balcony was doing it simultaneously in buildings not really built with either in mind.

800w sounds low to me, especially on 120v in the US, but the rules may have been in place for older less efficient / bulkier panels in mind.

Mind you higher powers just need a licensed electrician to sign off and usually also have them permanently wire it in as those setups won't need an AC side plug so the costs of essentially a generator hookup over a fixed tie-in isn't worth it, and they require notifying the local grid. Might be that beyond 10kWp the grid can tell you sorry-capacity-not-ready (but the grid will have to fix that soon, there are rules) but yeah.

This is complicated legalese. "For your own use" doesn't technical exist, you are outputting your solar production into the main grid - and this is capped at 800W for grid (and house installation) safety and stability issues. You need a meter that can run backwards, but you have the right to demand from your electricity provider that they install one.

Bypassing the grid and using your own storage infrastructure is AFAIK not allowed in Germany (there are heavy taxes on electricity, that you would be omitting - similar as to how you technically are not allowed to make your own Schnaps at home due to taxing).

Last I read them, electricity tax was only applicable for sale and certain situations that involve transferring power across parcel/plot boundaries. An entity is allowed to generate it's own local solar power for own local consumption, and for that it's perfectly fine to rent/lease the equipment/panels but you can't just tax-free buy electricity itself outside some limited situations that are to allow e.g. an apartment tower to use solar panels as cladding to then sell the power to the tenants instead of forcing every tenant to lease their own electrically independent section of the facade.

You need me, an electrician, for bigger installation. 800W can be done by everyone and doesn’t require registration to grid operator and tests. Some people don’t mind having illegal 1600-2000W installations, never heard, that someone got fined for that. Generated energy (if not consumed) is not paid for anyway.

I think it's the plug-in part that is limiting the power. Most of these sets you just plug in to a existing outlet, not wired into the electricity panel. Feeding in 800 watt directly into the circuit allows you to draw more than the rated 16A 230 volt from that circuit without tripping the breaker. The ~20A you can manage this way is probably within safety margins of most installations.

Germany is a litigious country, with most of the things insured.

If people started plugging a 2kW grid tied inverter in a normal power socket - as is the case for balkonkraftwerk - houses would start catching on fire.

Nobody wants that. Yes, regulations are necessary for a safe and civil life.

You're not allowed to burn down "your" apartment building, because you didn't understand that its wiring was not designed for the extra load, or that overloaded wires get very hot.

If you have a south (or SE or SW) facing wall without much shadowing from nearby buildings or trees, vertikal mounting does work OK. Do not expect to reach the panel's nominal Wp rating though, output will peak at 50-70% of that. But panels are cheap - if there's enough room, just overprovision twofold. Just take care to buy an inverter that is OK with such a bigger configuration. And vertically mounted panels will generate more power off-season than tilted ones.

How well does a biphasic panel work mounted vertically on a light coloured wall at least a meter+ away (depending on panel size) ?

Just clad the wall between the windows (if any) in panels? Eases the wind loading that way as wind can't really get behind them anymore.

Think of them as (glass) fence panels with a convenient mounting frame. Just respect their dislike for partial shading from objects that are "near" (cast a hard shadow with wel defined borders relative to the cell/grid size on the panel), and it'll be fine. If they are arranged to have substantially different sun intensity and/or timing, run them through separate MPPTs or use "power optimizers" that do the same effort but without requiring more wires back to central than the simple "one single string of panels" has.

Due to recent issues out there: calculate worst winter peak voltage and make sure there's a healthy margin to the peak allowed safe/no-damage input voltage to the MPPT/charge-controller/inverter.

Panels eat less of their own current at any given operating voltage, the colder they are. And winter mornings after soaking in night cold are worst case conditions for that as they had no time to heat up yet for the first minutes past sunrise.

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