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Ask HN: What can I do with extra electricity?

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Re: Ask HN: What can I do with extra electricity?

#52
> What can I use the waste electricity for?

You can't. That's really the end of it.

Lots have tried and failed. You can pick a fun project that you might get some skills from but it's not really a real answer.

It won't beat batteries which you've already spec'd out.

Best you have is move chores when you have extra electricity. Washing, download torrents, watch TV, run the pool pump, heat water, dry food.

Re: Ask HN: What can I do with extra electricity?

#53
post #29

Earlier quoted context omitted.

Instead of consuming the extra energy, OP could also provide it to another customer through the grid, by selling it back to the utility company. This would reduce the total amount of energy that needs to be generated from non-renewable sources. If OP increases their own consumption instead, those non-renewable kWh are still being generated and causing environmental impact somewhere.

This is being mounted on an RV, which is explicitly off-grid, and would only be intermittently connected at best. In my municipality they only do power buy-back from larger generators. Also most of it isn't going through an inverter, I'm using direct DC-DC, which is much more power efficient for what I'm doing. So that means more cost for inverters, which I'd consider paying even if at the scale I'm working at it wou…

Thanks for the reply - makes perfect sense in your case.

Re: Ask HN: What can I do with extra electricity?

#56
post #24

You can sell it to your local utility company. You will get paid for it, and another power plant somewhere (maybe a coal power plant) will need to produce 1 kW less power.

Unfortunately that won't work in my municipality, as they only do that for larger customers. The problem is that it's not a "smart" grid, and having random customers pump power back into the grid can cause lines that they thought were dead to actually be energized during repairs. They need some way to shut off the buyback during repairs, and right now they don't have that. Also I'm not sure that the amount of power I…

This is exactly why many grid tied inverters like the SMA Sunnyboy range won't start or auto shutdown if it doesn't detect power coming from the grid.

Re: Ask HN: What can I do with extra electricity?

#57

Earlier quoted context omitted.

I'm in Nova Scotia, Canada. So I'm expecting worse than that, but it's hard to get realistic numbers. Those numbers are a fair bit worse than the worst cases I was looking at, which assumed winter panels would be ~25% efficient on average.... So that assumes a 3kw system is producing around 4kw-hours per day. I'll need to see if that's realistic.

The middle of Nova Scotia is about same latitude as me, but you guys probably get waaaaay more snow and I am on the desert side of WA state. We get a ton of sunshine. How are you going to clear off the snow? I have 54 panels and it is a big chore to do it without scratching the panels, so I don't even try. Snow slides off like a metal roof, so you have that. Do you guys get more overcast days? If so your panels may b…

That program didn't exist last time I looked into it, I'll definitely be following up on it. I actually know some people who would be great candidates for small wind turbines under it, so I'll be mentioning it to them.

Another challenge is that the solar is part of an RV, which makes permanent grid tie challenging, but I'm definitely considering just "donating" it when I can at this point.

Re: Ask HN: What can I do with extra electricity?

#58

Earlier quoted context omitted.

The middle of Nova Scotia is about same latitude as me, but you guys probably get waaaaay more snow and I am on the desert side of WA state. We get a ton of sunshine. How are you going to clear off the snow? I have 54 panels and it is a big chore to do it without scratching the panels, so I don't even try. Snow slides off like a metal roof, so you have that. Do you guys get more overcast days? If so your panels may b…

That program didn't exist last time I looked into it, I'll definitely be following up on it. I actually know some people who would be great candidates for small wind turbines under it, so I'll be mentioning it to them. Another challenge is that the solar is part of an RV, which makes permanent grid tie challenging, but I'm definitely considering just "donating" it when I can at this point.

Unless you're sure that your donations on will be used on-premise immediately, then you will actually cost whoever is your host. (It may even have to be on the same 120V phase tap from the 240V coming off the street transformer, but I'm not sure.) Standard electric meters are not sensitive to power direction - power going into the residence or power going out. They only detect volume of power movement, but not direction. When you buy a grid-tie system, the power company has to come out and swap your power meter so that the new one will essentially run backwards if you happen to have net power going back into the grid. Anyways, fully solar systems are harder at our latitudes than if you live in California or closer to the equator without the strong winter demands. Maybe just fail-over to propane as needed.

Power inverters need to be manufactured grid-tie style. They have a phase lock loop ( IIRC ) that ties into the phase of the grid and they need to not generate power if power is down on the grid in grid-mode, otherwise guys working on the lines can be electrocuted when they think they have turned off power lines.

Also, if you're donating back, you need to be concerned about amperage on that circuit and it needs to be dedicated, in addition to following all your local power code. If you just so happen to generate 14Amps net and then a device on that same circuit consumes 28A, then the panel 15A breaker may not trip, but parts of your circuit have 28 Amps flowing:

                            Load
                            (28A)
                              ^ ---14A--->+

Re: Ask HN: What can I do with extra electricity?

#59

Earlier quoted context omitted.

Unfortunately that won't work in my municipality, as they only do that for larger customers. The problem is that it's not a "smart" grid, and having random customers pump power back into the grid can cause lines that they thought were dead to actually be energized during repairs. They need some way to shut off the buyback during repairs, and right now they don't have that. Also I'm not sure that the amount of power I…

Most net metering arrangements require a manual power disconnect switch for your rooftop generation [1] for utility workers or first responders, and NEC requirements require inverters to shut down ("rapid shutdown") if they can't sync to the utility to prevent backfeeding power during maintenance (caveat: if you have local energy storage, the inverter will island and continue to provide power from local storage). I w…

Thanks, the net meter looks to be a new pogrom. I wasn't previously aware of it.

Re: Ask HN: What can I do with extra electricity?

#60

Earlier quoted context omitted.

Most net metering arrangements require a manual power disconnect switch for your rooftop generation [1] for utility workers or first responders, and NEC requirements require inverters to shut down ("rapid shutdown") if they can't sync to the utility to prevent backfeeding power during maintenance (caveat: if you have local energy storage, the inverter will island and continue to provide power from local storage). I w…

Thanks, the net meter looks to be a new pogrom. I wasn't previously aware of it.

Happy to help. Please share the net metering info to anyone who might be considering rooftop solar/distributed generation in your area!
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