‘Energy independence feels practical’: Europeans building mini solar farms • Hacker News Board

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#321

Post by adrianN » Sat, Mar 28, 2026, 4:19 PM UTC

itsmek wrote: post #160

misja111 wrote: post #27

Can anybody explain how these plug-in solar panels work? I am suprised that it's possible to just plug them in to your wall socket. For instance, isn't it complicated to have their output be in perfect sync with the frequency that comes in via the electricity net? Because to me it seems that if they won't, you will have lower benefits or even a net minus after plugging it in.

Syncing them with electricity is easy. The hard part is preventing export to the grid which requires either a compatible smart meter that can communicate with your panels or a transformer clamp installed by an electrician. My understanding is some meters measure both directions equally so if you do end up exporting power you can conceivably increase your utility bill.

Why would you want to prevent export?

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#322

Post by PaulDavisThe1st » Sat, Mar 28, 2026, 5:02 PM UTC

skippyboxedhero wrote: post #296

PaulDavisThe1st wrote: post #213

Earlier quoted context omitted.

I can't speak for the UK, but ... I did my own install of a 6.7kW ground-mount array. The materials cost me about US$12k. That meant just 7-10 years until payback. Sure, I saved on labo(u)r costs, often the most expensive part of the work, but the overall point remains ... it absolutely makes sense, at least in the "right" parts of the planet.

It isn't just the "right" parts. Yes, the UK has less sun but ground mount is not happening in the UK because average dwelling size is so mall. So typically installed on roof of much smaller properties which costs significantly more for far less solar panel. Detached homes are also rarer than the US because of the issues with supply of almost all goods/services in the UK so there are more issues with tree cover. And,…

I confess to still not understanding why roof installs cost so much more.

My ground mount array(s) required concrete foundations that were 5' deep and 17" in diameter, and the frame cost $2k in iron piping. There's nothing remotely comparable in a roof install.

I guess people just charge more because "we're on your roof, which is tricky".

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#323

Post by iugtmkbdfil834 » Sat, Mar 28, 2026, 5:22 PM UTC

conk wrote: post #233

PaulDavisThe1st wrote: post #205

Earlier quoted context omitted.

> The solar systems, as currently pushed, are designed to be carefully monitored at all times; if you read the contract ( in IL anyway, but I presume it is common, because my mom had a similar experience ), I have to give the company a way in every time they desire to look at the panels. I did my own install of a ground mount 6.7kW array. I initially declined to connect to the inverter manufacturer's monitoring, beca…

There are inverters with local only monitoring and control. I have one integrated locally with home assistant. You can also add an external current transformer and monitor the production with that independent of the inverter.

Oh? Could you go into any details? I will clearly need to do some research now, but if I can save myself some time, all the better.

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#324

Post by ericd » Sat, Mar 28, 2026, 5:33 PM UTC

yawaramin wrote: post #245

ericd wrote: post #204

Earlier quoted context omitted.

It's aluminum, glass, silicon, and some conductive metal. Surely you all have those materials. And even if you don't make them yourselves, they aren't make and then burn like fossil fuels, they are durable infrastructure, you don't have to replace them often - they have an expected lifespan of >30 years. Buy as many as China will sell you, and once you have more than enough installed, you're good for a long time, reg…

> expected lifespan of >30 years More like > I think being reliant on the fossil fuel supply chain for so long France isn't. And they are net exporting their (nuclear fission) electricity to their neighbours who shut down nuclear power plants.

Most panels have a 25 year 80% production warranty. Unless they're planning on being out of business, they're not planning on them lasting <25 years. So their useful life is significantly longer than 30 years, unless we come up with massively more efficient panels and the land opportunity cost is high enough that we should swap them out rather than let them just keep pumping out electricity.

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#325

Post by ericd » Sat, Mar 28, 2026, 5:36 PM UTC

brabel wrote: post #298

lpcvoid wrote: post #256

Earlier quoted context omitted.

Yes, and France currently has a huge problem with keeping their plants online in the summer when it's too warm. And building new plants is outrageously expensive, see Hinkley Point C. Oh, ans you still need to import fission material, so you're dependent again on other countries. Nuclear was good in the 70s, now it's beaten thoroughly by renewables.

The Swedish government is very pro renewables, yet it is initiating large investments in nuclear because they believe it is the only way to ensure enough electricity for the larger and larger need for it in the near future. I’d say they have some good information to base that decision on, since you’re right it’s really expensive, but also it’s the only way to get large amounts of production when the sun ain’t shining…

Right, a mix of uncorrelated sources is much more resilient than 100% renewables. Of the cleantech industry people I listen to, none of them are advocating for 100% renewables, you need a mix for grid reliability. But renewables can take on much of the load. And overpaneling can help significantly, and makes a lot more sense now that solar is super cheap.

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#326

Post by testing22321 » Sat, Mar 28, 2026, 5:50 PM UTC

iugtmkbdfil834 wrote: post #194

JumpCrisscross wrote: post #183

Earlier quoted context omitted.

> Those proactive in a reactive world are often mocked and laughed at I'm going to start calling this a Jehovah's Witness complex. Where amplified, mostly imagined mockery of an incredibly dominant view, at least in group, is used as evidence of that view's righteousness and, by extension, rightness. > prices will not be dropping...Energy grid decentralization is occurring Cost versus resilience. A low-cost grid has…

I think the answer may be more complex than that. I mean, I know you are not wrong. My boss only recently made a crack at how pointless solar energy is in the world of cheap gas. But it is not just cost. It is a level of control the contractor has over it. The solar systems, as currently pushed, are designed to be carefully monitored at all times; if you read the contract ( in IL anyway, but I presume it is common, b…

That sounds utterly terrible. Don’t buy what they’re pushing.

Here in Canada I did a half DIY install, I own everything, forever. Zero out of pocket, interest free loan. Over 30 years I’ll pocket about $25k

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#327

Post by testing22321 » Sat, Mar 28, 2026, 5:51 PM UTC

euroderf wrote: post #319

t0mas88 wrote: post #193

Earlier quoted context omitted.

There is a real safety issue with plug-in solar panels and plug-in batteries. Things go wrong if other loads are on the same circuit, which is almost unavoidable with a plug-in system. Consider a circuit in a home, designed to carry 16A like a common EU/UK circuit, protected by a 16A breaker. Then plug in solar or a battery that delivers just a small 10A. Now in case some other thing on that circuit draws 26A, the br…

So the danger comes when you plug the solar into a wall socket but there are other devices connected to the same fuse of circuit breaker. So... Instead of the solar having a plug that goes into a wall socket, why not have a plug on it that screws directly into the fusebox ? Then you know that it is the ONLY device on the circuit.

Then a homeowner can’t install it themselves in 5 seconds for free, take it with them when they move, etc.

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#328

Post by aaronmdjones » Sat, Mar 28, 2026, 5:55 PM UTC

formerly_proven wrote: post #294

fy20 wrote: post #223

Earlier quoted context omitted.

These are not just circuit breakers/MCBs, they are RCBOs which combine an MCB + RCD in a single unit. RCDs traditionally only measure - and protect - current flow is one direction, so if you are using them for solar you need a bi-directional unit for full protection. The device will not be damaged, it just won't protect you. However in the case of a UK home, where you may have a single ring circuit connecting all the…

Outside the UK, neither RCDs nor RCBOs (type A/AC) are generally distinguished by bidirectionality (all search results about this being .co.uk), since the RCD part of these devices is just a current transformer driving a trip solenoid; there is nothing in it that's powered by the line, nor something which could sense net power flow direction. The situation is different for AFDDs or type B RCDs, since those have activ…

> Answer #1: Many UK RCDs/RCBOs are actually single-pole devices and don't disconnect the neutral.

This is not correct; all type AC and type A RCDs used in British consumer units disconnect the neutral as well. Some RCBOs do not disconnect the neutral and this is a problem in some circumstances. The datasheet I linked for Wylex NHXS1 RCBOs explains that these ones do disconnect the neutral.

> Answer #2: It looks like some/many one-module wide UK RCBOs _do have_ electronics in them [...] but if backfed for longer than the disconnect time that might be enough to toast the solenoid or the driver

This is correct. For an example of this construction in an RCBO, see [1]. This illustrates that if the supply is connected to the "To Load" part of the schematic (toward the end of the video), as it would be if the supply is a solar PV inverter with battery storage, then it can continue powering the electronics and be shunted out by the thyristor after it has supposed to have tripped, very quickly burning itself out.

Bidirectional RCBOs are not designed in this manner. They have more complicated circuitry that makes them more expensive to manufacture, but are absolutely required in situations like this if you don't want your protective devices to burn and/or explode when they operate.

> Notably neither of these has anything to do with the direction of power flow.

Yes it does, because if the power is flowing backwards to how they designed it, that is backfeeding it, keeping its circuitry powered after it should have been disconnected.

[1] https://www.youtube.com/watch?v=8kWIITspYvk

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#329

Post by testing22321 » Sat, Mar 28, 2026, 5:55 PM UTC

edot wrote: post #312

giantg2 wrote: post #311

Are they using EU manufactured solar panels? If not, I don't feel like this is real independence.

Exactly. This is such a goofy idea, that you can buy something from China and use it in the EU and suddenly you’re “energy independent”. No, you’re China dependent. I guess the argument would be that solar panels last a long time and thus you’ve bought yourselves 20 years or whatever the life span is, of energy independence from China? But you’ll need new batteries sooner than that.

With rooftop solar and an EV I’m a lot less dependent on China for the next 30 years than everyone around me is on the Middle East daily for gas to drive and natural gas for heat.

Re: ‘Energy independence feels practical’: Europeans building mini solar farms

#330

Post by testing22321 » Sat, Mar 28, 2026, 5:58 PM UTC

adrianN wrote: post #321

itsmek wrote: post #160

Earlier quoted context omitted.

Syncing them with electricity is easy. The hard part is preventing export to the grid which requires either a compatible smart meter that can communicate with your panels or a transformer clamp installed by an electrician. My understanding is some meters measure both directions equally so if you do end up exporting power you can conceivably increase your utility bill.

Why would you want to prevent export?

We just got rooftop solar in Canada. Our meter was old and had to be upgraded to bidirectional.

We were warned if we turned on the system before the meter upgrade the old meter would sum together power coming from the grid and power going into it from our solar and we would be billed for the combined.

So with some old meters you don’t want to put power into the grid.