[sdk77]

It's nice to have solar panels, I have them too and while they do generate even more electricity than I need, they do so in around 6 to 7 months peaking in July. So in winter, it's grid power and in summer I might need to pay to feed in the surplus. This is in the Netherlands. It's kind of sad to see all that electricity unused in summer, and knowing I could have enough for all of the winter if only there was some way to store it, all of the 1MWh..

[itishappy]

> ... in summer I might need to pay to feed in the surplus.

You're allowed to just disconnect solar panels. It's free and does not damage them.

[sdk77]

Sure. Of course. Not being allowed to disconnect them would be ridiculous. But do you want to keep an eye on the market every day, and run to the breaker to turn on an off your inverter? No. So you need a solution for that. Then a battery is much more interesting.

[itishappy]

Completely agree. I mainly mention it to dispel any notions that solar panels can expose you to financial risk due to negative energy prices. This is trivial to address. Negative prices should only be a concern for plants that can not be quickly or easily shut down, like thermal plants (coal/gas/nuclear).

[kleiba]

This seems like a problem that should be relatively easy to solve with technology.

[WJW]

This is in fact what my home installation already does.

[quickthrowman]

You could implement something pretty easily with a relay or contactor and an ESP32 and a way to monitor the spot price, or just buy a system with that feature already built in.

[amelius]

Note: doing this manually every day (breaking the circuit) can increase the risk of damaging your installation.

[mikehotel]

How can the use of a switch damage your installation?

[GeoAtreides]

inrush current, mechanical wear, thermal stress on some components (mosfets, transformers, etc)...

[Larrikin]

Could you just use Home Assistant to do this?

[EasyMark]

True hacker would use web scraping to get the rates and a bash script to turn the switch on and off based on rates

[Larrikin]

That's the entire point of Home Assistant, I'm currently writing an integration for my electric company. I'd argue the college junior programmer would try to do it from scratch instead of leveraging the solution that gets you 90 percent of the way there out of the box.

[Ella-e]

You means something like HEMS. A controller to connect everything in house ?

[euroderf]

with a scrolling LED display for streaming updates.

[quailfarmer]

All modern inverters have control interfaces that allow them to fold back their power output on command, this can be set up to track feed-in rates going negative.

[Ella-e]

Wow,interesting. But， the idea of storing the surplus electricity, it does raise a question about the energy consumption of storage batteries. i has been researching European home energy management recently, especially with winter approaching. Just share information. enjoyelec HEMS (Home Energy Management System). Use AI optimize energy usage in households. With features like real-time monitoring and intelligent control, it aims to reduce energy waste and potentially lower costs. Maybe can get some money from grid to pay from winter electicity bills.

[titanomachy]

> need to pay to feed back in the surplus

Why not have the panels disconnect themselves in this case? Is this too small an expense to justify the cost of additional hardware to manage switching on and off?

[sdk77]

It all depends on the situation. Here in the Netherlands almost everybody has an PV installation with no way other than the breaker to turn it on and off. Some inverters do have an interface, and sometimes it's available. Even less people know anything about this at all, they just had panels installed. The technical solution is simple, bit implementing it will cost much more, I assume.

[defrost]

> This is in the Netherlands. It's kind of sad to see all that electricity unused in summer,

This is literally what local and state government is for; talk to others and get policy moving on excess energy being used to generate bulk stored energy at scale for winter months, be that gas, deep thermal storage, tradable goods to offset winter costs, etc.

[euroderf]

Doesn't anyone smelt their own bauxite anymore ? sigh

[defrost]

Ammonia products are easier, particularly with excess peak energy.

Yes, we still have six active bauxite mines providing feedstock for six alumina refineries ... they're optimal as pipelined processing and not great at switching on|off with energy surges.

[euroderf]

I wonder if ammonia might be doable at residential/DIY scale. Then you have to (a) store it safely, and (b) have a way to use it - not many people have a personal marine application.

[defrost]

Maybe .. but in an urban area with many houses, each with solar panels, it seems inefficient to have mini home chemical process factories, particularly with intermediate steps involving explosive gases.

I'm in favour of home PV and community batteries | larger area "peak" use industries - it's a sensible long term use of cyclic energy production.

[euroderf]

To further follow up... outside of the cities, Finland has a LOT of lightly populated land, and since EU entry, farming is not exactly going great guns. Land is cleared.

So AFAICT mass PV is a distinct possibility, and if it can be leveraged to reduce the cost of wintertime energy usage, it will find a firm foothold.

[euroderf]

My use case is Scandinavia. The summer has an absurd oversupply of sunlight (weather permitting). Capturing this for winter usage is the poser.

[woleium]

electrolysis of water to hydrogen and oxygen seems sensible. could be done at home, but probably best at community scale

[theturtle32]

"pay to feed in the surplus"? In my U.S. context, this sounds surprising: are you saying that sometimes the energy utility CHARGES you money when you feed solar energy to the grid? That sounds... bizarre?

[bdhdbebebeb]

If I were to deliver you 1000 gallons of milk that expires in 10 minutes*, would you pay me or want to charge me for that priviledge. Assume you have enough milk already.

* (< 1 millisecond for electricity but hey for the milk analogy say 10 minutes).

[theturtle32]

I don't think this is an apt analogy. Electricity is pulled, not pushed. (Well, I realize it is actually a bit more complicated than that, but for the purposes of this conversation, I think the generalization is sufficient.)

If there is no grid-side demand for the energy from my solar panels, then they're not going to be force-feeding it to a grid that doesn't want it.

When you plug a light bulb that's rated to draw 20 watts into a power source capable of delivering 1000 watts, it doesn't blow up your light bulb, because the light bulb only takes what it needs from the source.

[Ekaros]

It is more complicated on grid level. Some inverters might be smart enough, but some are not. Thus there is both push and pull going on. And this can affect voltage and frequency.

[noahjk]

This is the only reply I understand, so I’ll follow up here - in this case, is the end user paying to push the energy into batteries that the power company owns? Or is the extra energy just dissipated somewhere? Or does the power company stop producing their own energy once the grid is saturated? (I believe that electricity doesn’t actually flow like water, so it’s not the exact same electrons that the solar panel is producing which would be stored on batteries or dissipated somewhere)

[orwin]

[edit] if you don't produce the exact amount consumed at the exact same time, the current will loose its phase and the effective energy transported will be reduced, while producing surtensions at different grid points (don't quote me on that, but accumulator try to keep the phase, and too much divergence can cause their failure from what I understand. But I'm no physic major and I might be completely wrong). Grid coordination is vital.

The main issue with consumer solar connected to the grid is the lack of predictability. The reason why we charge if you put electricity on the grid when too much energy is produced is because we did not plan on offsetting this production, and the network people have to keep it balanced. Reducing the output of thermal fossil plants is usually free, but while we can module nuke plants, it's best and way cheaper when that is predicted (also, opportunity cost is high, so for privately owned nuke plants, it cost even more. EDF is the bitch of the European electricity market so they eat the opportunity costs, but they are the only plant owner who does it (and I won't talk about ARENH here, but again, EDF is the bitch of the EU). Then, when really to much shit is on the grid, and you have reservoir space, you pump the water up the STEP (batteries, but better). Up to 4500€/mwh if unpredicted (it's never actually that, but it's the price seer in the SPOT command order). And lastly, if it's the only solution, wind/solar farms are shut down. Again, if predicted, good time to do the maintenance.

In the future consumer grade installations will probably come with a lot of stuff to help with the lack of predictability. I don't love it, but that's actually my current job (well, I actually love the actual job, really interesting shit, I'm not so sure about the moral implications of even more surveillance. Because we do have the geoloc of the newer installations. We don't link it with anything relevant yet, and it's anonymous for the moment, but will it stay that way?)

[noahjk]

Interesting!

Is there a reason that consumer solar can’t be accounted for as smaller stable nodes in the system (sounds like they are still considered volatile and not a reliable source of inflow power)? For instance, maybe a rooftop solar array can easily be sucked up if the home decides to do a few loads of laundry that day, and therefore since there aren’t enough homes with solar arrays, it’s harder to predict an average influx per day from consumer solar to power the grid?

Are there any goals to shut down larger plants or not build larger solar fields by instead subsidizing distributed solar on peoples’ property?

Utilities are so interesting. The other afternoon I was looking out at the hills as the trees change, and said to my friend, “what a beautiful view… besides all these power lines! Although, I’d rather have the infrastructure than an unmolested view…”

[orwin]

> Is there a reason that consumer solar can’t be accounted for as smaller stable nodes in the system

It's not my subject (i mostly work on automation for the network and security teams), but when i consider some changes we did last year, i think the issue with consumer-grade solar is that we didn't know where installation number XXXX was set, not even which country it was from. That is changing, we will now know if it's near Paris, near Munich, near Barcelona... That will probably help with output prediction. I think at some point there were talk about using geoIP, but that was shut down for some reason (i think it was a mix of geoIP lying, and privacy/GDPR considerations we weren't ready to tackle on yet).

[toast0]

When there's too much energy available for the grid, and the price goes negative, producers are paying for someone to use that energy or paying another potential producer to reduce their output.

Some industrial users have variable demand, and a lower (or negative) price could encourage them to use more. A multi-region internet service might send more traffic to a datacenter with negative electricity prices, even if in increases latency for users.

Some producers need time to modulate output, and stopping and restarting can be expensive. Solar and Wind are at least technically easy to start/stop, but subsidies may make it economic to pay the grid to deliver electricity; either because of contracts/subsidies, or because the expense to deliver unwanted electricity is less than the expense to monitor pricing and reduce production.

[bdhdbebebeb]

What happens if no one takes the power (not one solar installation but lets assume lots of surplus power). Does it screw up the grid? Increase voltage/frequency?

Would this lead to grid needing to be shut down?

[toast0]

Yes, if nobody removes the excess, grid frequency will increase. Running too high or too low frequency can damange equipment, on both the supply and demand sides.

[dtech]

When there is a lot of wind and sun simultaneously there is effectively too much electricity supply on the net, and day-ahead prices drop negative. This is partially fueled by flat subsidies per unit produced (has been fixed for a while for new installations), so producing when there's oversupply can still be profitable. Also most households have a flat energy rate and can amortize their energy usage over the year, so they will always keep their solar panels on even if the energy is less than worthless.

US pricing works very differently, especially in Texas.

[Ekaros]

Purchasers want to make margin on anything. So they charge this on the seller and then on buyer. Also with how markets work it is not like there isn't risks or need to at least some level forecast how much you will be buying and then selling. So their cut also covers this work.

And finally electricity is a spot market. So there is agreed price for certain period and in some cases market can be distorted and that price can be negative. It could be idiotic subsidies or production that can't be ramped as effectively. Or someone does massive mistakes with their bids, think of trading bots going wrong.

[pierot]

Yes, prices can go negative if you have a dynamic energy contract.

[Gare]

Maybe you could use the IJsselmeer as a pumped storage hydro ;)

[spacesanjeet]

Isn't there a way to sell the unused solar power to the grid in summers and during winters the grid sends back the power needed to you at a discounted price?

[sdk77]

Well, until '27, I'm allowed to use the grid as a free battery, basically, this is a kind of government subsidy. But that will end, and the contracts available will be fixed price with a feed in tariff or dynamic (realtime) market price, but then prices can and have been negative during peak solar hours. A battery can solve this only for a bit, and maybe with smart algorithms it can be trading on the electricity market full time, I'm not sure if that makes enough money for the grid power in winter.. it's nice to think about though.

[ccozan]

or you get a battery. Is just great. I have 3.5kw solar power witha 9kwh battery. Very very seldom it switches to power line. And this is in south Germany, maybe a bit sunnier than north but still - it rains a lot/cloudy, sun is sparse.

[skybrian]

It seems like that works for daily cycles, but isn't that very expensive storage for one cycle a year, which is what you need to save energy for winter?

[ben_w]

Depends how close to the poles you are. A lot of the world can do this fine by sizing the PV for winter; too close to the poles and there's not going to work — you either need to diversify power generation by kind (wind, wave, hydro, geothermal all work too, but again geographically constrained) or by distance (the maths says we can build an adequate and literally global power grid for an affordable quantity of aluminium, shame about the politics).

[jjtheblunt]

Any advice on battery brands and features you could share?

[ccozan]

yes , check this guys https://www.anern.com/products/solar-battery/

[jjtheblunt]

Thanks

[bitmasher9]

If every household did this we would have massive problems. We would still need a base load amount in the winter, and in the summer there would be an over abundance. The price of electricity would swing between essentially free in the summer to higher than normal in the winter, because the cost of operating base grid power would be about same but they would need to cover all operating costs during the winter.

[fallingsquirrel]

Utilities should charge a separate connection fee and per-kWh rate if that's what matches the economic reality of their business. I don't see the summer abundance as an issue. It means we get to shut off the fossil fuels 8 months out of the year. The remaining 4 months, everyone pays a little more per kWh, averaging out to the same cost over a full year. What's not to like?

[fragmede]

The economic viability of a fossil fuel plant that's only used 4 months out of the year.

If the plant shuts down because it's no longer economically viable/doesn't cover operating costs, what happens next winter?

[dtech]

The electricity price in the winter will go up until either the plants are viable again or alternatives become viable.

[forgetfreeman]

Ostensibly it gets replaced by a grid storage array and sufficient renewable inputs.

[euroderf]

> in the summer there would be an over abundance.

This ain't gonna happen. Air conditioning will be saving lives.