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Plug-in solar is coming. Plug-in batteries should follow

regen.co.uk

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Re: Plug-in solar is coming. Plug-in batteries should follow

#91

Post by satiric »

gambiting wrote: post #78
satiric wrote: post #45

Plugs and sockets have the wrong gender for this. On the battery, you'd have a male plug with live 240v contacts, ready to short against anything, or anyone, that's conductive. This is the same reason why male-to-male extension cords are labeled "suicide cords".

Well, yes generally speaking. But the way this works with these plug in panels is that the micro inverter won't actually start delivering power to the grid in the absence of an energised plug in the first place. So just sitting there, the contacts are completely harmless. Obviously actual physical safety where you literally can't touch the contacts would be better.

How do you detect that it's plugged in? Just detecting voltage would mean that you'd unplug it and it would stay energized, right?

Re: Plug-in solar is coming. Plug-in batteries should follow

#92

Post by danmaz74 »

jonatron wrote: post #82

I don't see the point in panels without a battery, so I'm looking at a DIY system. RCBO for new circuit = £20, 5.12kWh battery = £700, ~3kW hybrid inverter from eBay ~=£400, Panels ~= £100 each. I'm not the including cost of a registered electrician for a new circuit in my case.

The plug in "balcony panels" are usually limited to 800W here in Europe, so having them without a battery can make sense because you're probably going to use that power on the spot most of the time.

Re: Plug-in solar is coming. Plug-in batteries should follow

#93

Post by hnaccount_rng »

Animats wrote: post #55

There are several variations on this idea, and the web sites are confusing. First, there are ones that are just a big UPS. You plug them into the wall, and plug loads into them. They may try to level your power usage. No problem with that. Good for refrigerators. That seems to be what "Pila" is selling. This class of device seems to come with deceptive ads which do not show cords from loads plugged into the box. Then…

That’s largely correct but misses the point that the battery+pv system is legally only allowed to feed in 800W [1]. On our circuits you can draw ~3.5kW without tripping the breaker. This brings you to 4.3kW max load, which - as far as I understand - is still what all the circuitry must be rated for anyways.

The downside is that we have three phase power supply anywhere halfway recent. And that only gives you a single phase. In _most_ cases that’s fine, because you get a net-sum of all three phases at the meter, but technically you are only drawing/supplementing one out of three phases. In practice this likely doesn’t matter since different house put theirs on different phases and it all washes out.

[1] the DC side can have up to 2kW of panels. But that’s not visible to the grid

Re: Plug-in solar is coming. Plug-in batteries should follow

#94

Post by hnaccount_rng »

satiric wrote: post #91
gambiting wrote: post #78

Earlier quoted context omitted.

Well, yes generally speaking. But the way this works with these plug in panels is that the micro inverter won't actually start delivering power to the grid in the absence of an energised plug in the first place. So just sitting there, the contacts are completely harmless. Obviously actual physical safety where you literally can't touch the contacts would be better.

How do you detect that it's plugged in? Just detecting voltage would mean that you'd unplug it and it would stay energized, right?

They need the grid frequency to generate AC. Those inverters are only allowed to be grid-following (at least for the plug-in part. I think there are systems that provide a -to-load socket that can be a PSU)

Re: Plug-in solar is coming. Plug-in batteries should follow

#95

Post by AndrewDucker »

cyberax wrote: post #10

Why? Just make it possible to buy "shares" in a larger battery bank, if you must. Home batteries make total sense for off-grid systems or as a backup power source. But plug-in batteries are not designed to do either.

Because there are not enough of these large battery banks, which require planning permission to build.

Whereas you can buy a battery that will save you money over a 5 year period and get on with it.

(I'm hoping that enough of the larger ones get built that having one yourself doesn't make economic sense, but I suspect we're ten years out from that)

Re: Plug-in solar is coming. Plug-in batteries should follow

#96

Post by angry_octet »

Symbiote wrote: post #71
Scoundreller wrote: post #50

Earlier quoted context omitted.

What makes it easier on 240v systems is that your entire household is on the same “circuit”. If you’re on a 120v system, there’s a ~50/50 chance that your load is on the wrong side (except for 240v loads where you’ll imbalance things a tad but it should average out). Unless you’re in an apartment/conso and have 208v instead of 240v… dunno what happens then.

This is true for the British system, except for the largest houses (6+ bedrooms) where you'll have a three phase 415V supply. Elsewhere in Europe it varies. Even small properties in Denmark and I think Germany have a three phase supply, my oven and stove use it directly.

There are multiple circuits on each phase, you would still need to limit current per outlet to 10A (8A sustained). If it's a dedicated circuit then 15A is fine, but usually that means a separate run, and in that case you can just have 20A or 32A.

When you have "three phase 415v", the 415v is the phase-to-phase voltage. Unlike the US 180 degree split phase 220v or 208v p2p, consumer equipment is not wired phase-to-phase unless it is 3-phase.

It's interesting that Europe has 3 phase cooktops, we usually see 32A single phase in Australia, homes rarely need more than 7kW per circuit. Aircons, pool heat pumps and EV chargers are the 3p loads.

Getting a 3 phase PV inverter is worthwhile if you have sun synchronous loads, like pool heater/chillers, across the phases. Then you will want a 3p battery inverter for the same reasons.

Re: Plug-in solar is coming. Plug-in batteries should follow

#97

Post by HWR_14 »

labcomputer wrote: post #51
bsder wrote: post #40

Earlier quoted context omitted.

> Yet in most locales it's illegal to disconnect from the grid. That's kind of ... required? Otherwise you have a bunch of people who are off the grid until the sun doesn't shine for a week and they run their batteries down and then they all try to connect simultaneously and collapse your grid. Most places I know of don't care if you never connect to the grid--you get your exemption and get on with life. However, onc…

Are you being deliberately obtuse? It is illegal to discontinue your relationship with your local electrical utility. As in, completely disconnect from the grid, cut the wires and never look back. As the previous poster said, charging for the “privilege” of connecting to the enormously-valuable grid would be a little bit defensible if having a connection were not legally required in most places.

I have no idea where it would be illegal not to connect to the grid. You can just not pay your electric bill.

Re: Plug-in solar is coming. Plug-in batteries should follow

#98

Post by angry_octet »

vvbull wrote: post #81

What happens when a consumer buys three and sticks them on the same 20 amp circuit? Cause people will definitely do that. Going to be some warm walls.

800W peak * 3 is only 2400W which is fine, it's very unlikely to be pumping out that for long. Now if you put in 6 of them you will have problems, but this is the same problem as people plugging in multiple loads, and circuit breakers handle this fine in practice.

Perhaps the bigger risk is a mix of loads and supplies on the same circuit, which could result in large currents on runs without a circuit breaker. Cheap extension cords are are possible problem too.

Arguably the plug in PV should have to talk to a house bus controller, which controls generation and loads. Unfortunately the standardisation process is impossible.

Re: Plug-in solar is coming. Plug-in batteries should follow

#99

Post by angry_octet »

gambiting wrote: post #83
vvbull wrote: post #73

Earlier quoted context omitted.

The problem isn't the battery catching fire, it's that you no longer have a circuit breaker between your appliances and the generator. Meaning you could, especially if you have several batteries, push load through wires in the wall in excess of what is rated for.

Maybe you don't know this, but in the UK every single appliance has its own individual fuse right inside the plug.

You can have multiple loads and sources that are in-spec but the wiring between them is overloaded.

Re: Plug-in solar is coming. Plug-in batteries should follow

#100

Post by perpetuallunch »

mullingitover wrote: post #62
perpetuallunch wrote: post #52

Earlier quoted context omitted.

Since all we’re doing is opinions, and all opinions are equal. It’s a scam. All that money we’re coughing up for rooftop solar and batteries at home would be better spent investing in grid scale electricity generation, of any technology. That way the best ideas generate more profit than the lesser ideas, and market discovery can solve problems. Maybe governments could incentivise renters and home owners alike by disc…

> All that money we’re coughing up for rooftop solar and batteries at home would be better spent investing in grid scale electricity generation, of any technology. In my city we literally can't buy any more grid scale solar. We rely on the county for transmission, we're buying all we can, and we're maxed. So you either get solar installed or you're paying some of the highest rates for electricity in the country. I'm…

> in my city we literally can't buy any more grid scale solar.

Ok. That’s not the argument I was making though.

And neither is the rest of your comment a reply to anything I wrote.

Of course in the absence of the full suite of options, people will and should make rational economic decisions based on the options they do have.

And hopefully keep voting the bastards out until better options are on the table.

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