Is a smart electricity tariff worth it? | Hacker News Reader

Is a smart electricity tariff worth it?

shkspr.mobi

34 pointsedent27 comments

In a BBC video from the same domain, https://shkspr.mobi/blog/2017/11/talking-solar-batteries-wit..., it seems like the installation (panels and batteries) is £5.000 and that this a community trial in the Rosehill area in Oxford where the batteries are subsidized.

I think it is valuable to bake in fixed costs and maintenance when these things are discussed. Apart from saving the planet it is nice to see if a project pays itself in 2, 5 or 15 years . . .

The panels are on track to pay for themselves in under 10 years. The battery is a bit more complicated because of the direct subsidies.

But it is the sort of tech which could be built into every new home without dramatically raising the cost.

Thanks for the information. :-)

> If we're willing to change, our power bills drop.

This is the big thing. I think with modern renewables we have to change our behaviour. ie doing washing/drying when its windy, charge cars during the day instead of night.

You don't have to change your behavior. And if you're busy and making good money you may find it's worth it to just eat the tariff cost. In some respects this is the same scenario as toll roads, there is always a free way to get there - how much is your time worth?

There are already a lot of areas that have peak power pricing and, in fact, a lake I went to as a kid[1] actually took advantage of this by (at a scarily low efficiency) pumping water into the lake during off hours and running the turbines during peak usage - it's basically a giant battery (but, again, super inefficient in terms of the energy required to pump the water into the lake, still efficient enough to be profitable though).

[1] https://en.wikipedia.org/wiki/Smith_Mountain_Dam

Behavior matters but smart loads are IMO essential. E.g. we have a tanked water heater that shuts off during peak rates; no way we could accomplish that by hand every day. It's not hard to imagine from there, cars that monitor the 'net and strategize to reach X% state of charge by 9AM with the lowest total cost, or washing machines that wait for the price per kWh to hit some bar before they start running. (although frankly the direct power draw of a washing machine is almost nothing, it's all in the hot water)

We're already getting there a bit with smart thermostats for A/C. Refrigerators might be more difficult, although similar temporary demand response schemes could probably be made to work, e.g. every fridge is alerted to shut off in 30 minutes for 15 minutes, they all schedule cooling in advance, and then drop off the charts as a group for a short window of time. Perhaps you saw that a bank of clouds was about to roll over your panels.

Silent loads like your fridge make up a lot of the total power draw, and are also some of the most tied to the concept of permanent base load.

A 15% cost reduction – not bad.

Possibly interesting – I'm working on developing a similar battery - solar panel off-the-shelf system that would be suited for people who live in cities (e.g. if you want to put a solar panel on your balcony):

https://www.craftstrom.com/

15% sounds impressive but it's 60 GBP in absolute savings. That might just be enough to finance the hours it probably took to collect, compile and process all things necessary to make this calculation.

Per year. And assumes electricity prices won't go up.

It took me half-an-hour to grab the CSV files from my monitoring, a write a scrap of Python to work out the difference in prices, then double-check my workings.

I'm happy with that ROI.

£60/yr would be a good saving for a supplier switch, the comparision and admin from which could easily add up an hour's work. A good ROI indeed!

What do you use for monitoring your mains supply?

The smart battery provides the monitoring. It is literally a clamp on the meter to monitor import and export, and one on the solar panel feed to measure generation. Small bit of Python to grab it ever 10 minutes.

What would your advice be to someone with no electric car, no solar battery, no solar panels, and no subsidy available on them? Is the smart tariff still a good deal?

Depends on your usage patterns. If your job means you always get home after 7pm, or if you cook with gas, then it may still be worth it.

Likely in future calculations like this will happen automatically through smart meters.

Yes, this is true.

However the UK has been running its power generation asset into the sand, we are increasingly reliant on things like https://ukpowerreserve.com/

So I expect that with the relentless push to smart metres (which is an optional EU directive, irony or ironies) we will see peak costs rise to battle the loss in cheap spare capacity.

That's a battery storage company? You seem to be suggesting its a bad thing??

the battery bits they have are less than 10% of their portfolio. In fact I would go so far as to say that their battery offering is mostly hot air, as they boast about its capacity in MW, not MW-hours

if you look at their asset page:

https://ukpowerreserve.com/assets/

its basically small polluting gas an diesel gennies.

Hmmm this is interesting... currently i'm on a 2 year fixed, i live in quite an energy efficient flat and mostly keep everything off unless i'm home. Currently i pay roughly £16 a month for my electricity. Literally the only things on during the day would be: my alexa, my router, my hue hub and bulbs (in an off state), my fridge/freezer, my home hot water/heating thermostat and the apartment extractor fan.

I'd love to charge my laptop and phones off of a solar battery.

The author of the article has a smart battery which (as far as I can tell) outputs 460 watts of power [1] - whereas and a fan oven can use up 2.5kW†, a kettle 3kW, a shower 8.5kW.

So unfortunately you'll be importing electricity from the grid sometimes anyway, if you want to shower or cook when it's dark.

[1] https://www.moixa.com/solar-battery/wp-content/uploads/2018/...

†When the thermostat is turned on, that is. So the average consumption over an hour of operation will be lower.

That seems quite doable? You don't even need an inverter, assuming you don't use your laptop during the day, you could use that as the battery.

Worst case, enough 12v panels, 12v battery and cigarette lighter adaptors for phone and laptop.

Relevant: https://www.lowtechmagazine.com/2016/05/how-to-go-off-grid-i...

How much electricity do you use in a month for that £16?

By contrast, my apartment was empty last month with only zombie loads, the fridge, 2 routers, a set top box, and two Nest thermostats left on. My electric bill was $46 for about 150kWh. This is with no lights, heating, cooling, or hot water heater running. (Hot water is demand provided by the building and billed per gallon so not even a tank being kept warm)

150kWh in a month is about 200 watt continuous which seems a bit high but not double what I would expect.

And you’re saying you heat your water in that £16...?

Smart meters will let you switch tariff every half an hour, so you can just switch to a cheaper one for the "peak" period.

(I'm not sure this functionality is actually available yet - most suppliers are still barely rolling out SMETS 2 meters - the ones that aren't supplier-specific.)

I think it's safe to assume that the comparison flat tariff won't be available that way (or, at least, at that price.)

I've never heard of that. Where can I learn more about it?

You can't currently change supplier every half an hour. But with the right technology your supplier can change price every half an hour.

The only UK supplier with a half-hourly tariff is Octopus Energy.

- https://octopus.energy/agile/ changes price every half an hour, tracking wholesale prices.

- https://octopus.energy/outgoing/ works like Agile but also gives you half hourly export pricing. So you can sell excess energy from solar or battery storage back to the grid when the price is highest.

(Disclamer: I work for Octopus Energy)

OP here. That looks really interesting. Especially the V2G stuff. I've only just started with Bulb, but I'll certainly consider switching to you in future!

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