@majordennisbloodnok And of course, every kWh ‘downloaded’ when priced very low for use later is a kWh not required when the supply is dirtier and as well, a strain on the grid to provide that energy. during peak demand. Regards, Toodles.

Posted by: @toodles

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@majordennisbloodnok And of course, every kWh ‘downloaded’ when priced very low for use later is a kWh not required when the supply is dirtier and as well, a strain on the grid to provide that energy. during peak demand. Regards, Toodles.

Assuming, as mentioned before, that cheap leccy is green leccy, yes I agree. The trick is to sanity check that assumption every now and then otherwise it's just a purely financial exercise.

Posted by: @majordennisbloodnok

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I already use Forecast.Solar so I’m going to install Solcast alongside and see how they compare.

@ianmk13, I've been comparing Forecast.Solar and Solcast against reality for a while now and am reasonably happy to draw a few conclusions.

Firstly, my installation is remarkably free of complications, so forecasting should be pretty straightforward for those with the necessary algorithms. The elevation is pretty standard at 25 degrees and the roof is facing almost exactly South (only 5 degrees West of that). There are no shadow-casting structures or trees to speak of and all ground around us heads downward. Therefore, comparisons between the two forecasting integrations should be straightforward like for like.

Secondly, whilst there are certainly days when the forecasts go a bit screwy, Forecast.Solar tends to be pretty much bang on as far as could be expected from a prediction or, if there is a discrepancy, tending to under-forecast. In contrast, Solcast tends to be consistently over-forecasting and is less reliable for this particular site.

Thirdly, it's a pity that Predbat only allows for the use of Solcast, given other solar PV forecasts are available. To me, that's an oversight.

Fourthly, as I mentioned earlier in this thread, I have several pretty simple rules for ensuring the battery can be filled from solar PV, but topped up from the grid in order to pretty much guarantee we're running of cheap leccy during the Agile expensive time slots. I still haven't been able to accurately work out how much an accurately set up Predbat could improve on the benefit I'm already getting but anecdotally I believe I'm getting about 90% of the benefit for about 10% of the setup head-scratching. I'm also certain I'm putting the battery through significantly fewer charging cycles and therefore hitting its lifespan less.

Overall, I've decided not to pursue the more complex solution that is Predbat. However, I do have to say that being introduced to it has opened my eyes to an extra dimension of how people are using Home Assistant so the investigation has been a hugely useful exercise. Thank you.

@majordennisbloodnok I’ve not looked at Forecast.Solar, TBH, but I think it may be used in the ‘bundled’ HA Energy dashboard. My experience with Solcast is also that it forecasts on the optimistic side for peak Solar but Predbat has a fudge factor that you can apply.  The big benefit of Solcast for me is that it allows the modelling of my two roof elevations independently and provide a single forecast profile. Maybe Forecast.Solar can do this. Regarding the possibility of using a different forecast with Predbat, is this where a HA ‘helper’ would be useful? I agree with the 90%-10% principle and I’ve’ only put a little effort into installing Predbat although I’ve not let it take control of my inverter yet.  As you suggest, my view of the algorithms is poor and I am reliant on the author of the code. I’m presently otherwise occupied

but will probably enable Predbat control of my inverter in a week or so and see how it fares in practice.

Posted by: @toodles

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Posted by: @toodles

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@majordennisbloodnok And of course, every kWh ‘downloaded’ when priced very low for use later is a kWh not required when the supply is dirtier and as well, a strain on the grid to provide that energy. during peak demand. Regards, Toodles.

 

Assuming, as mentioned before, that cheap leccy is green leccy, yes I agree. The trick is to sanity check that assumption every now and then otherwise it's just a purely financial exercise.

That differs according to time of day.

The area where I live often has an over-supply of electricity from wind-turbines, mainly sited on the north-coast of Devon & Cornwall.

But at night, electricity is curtailed from those wind-farms.
The CCGT (closed-cycle gas turbine) plant just east of Plymouth takes the 'base load' in order to remain in closed-cycle mode.

Here's a plot showing Active Network Management (ANM) of a typical wind-farm in this region.
The darker the colour, the less electricity it is permitted to supply to the grid.

For the past 18-months I've also been comparing the amount of solar generation at my own house, and the proportion of solar generation in the energy-mix available from my local Bulk Supply Point. That's a transformer with a 33kV output.

There is usually a higher proportion of solar in the grid than I actually have from my roof-top panels.
The grid data is presented thus:

So, why do I generate proportionally less solar than my DNO is providing?

The answer is because the generation from renewable sources is supplied from Landulf in Cornwall, which is drier and sunnier than where I live on the west side of Devon, near Dartmoor.

Unfortunately I can't continue this line of research.
The grid-side data-feed is no longer available, and I'm seeking a way to replace it.

The energy-mix will change again once Hinkley-C goes live.
Because it has direct connection to the 400kV Transmission Grid, it will take precedence over the miriad of smaller wind- and solar-farms to the west.
Their electricity can only be accepted onto the Transmission network when there is available capacity.

If, at that time, I wish to continue re-charging my storage battery from the grid using a high proportion of solar/wind, then we'd need to have Nodal Pricing. That would allow an Energy Supplier to buy (and resell) electricity to consumers close to the sources of generation. Ie we'd consume it from the local Distribution grid, operating at 132kV and below.

In the absence of Nodal Pricing, my grid supply will increasingly have more nuclear power in it, whilst ANM will further curtail export from Cornish sites.

@transparent I have ‘an interest’ in Ripple Energy’s Derril Water Solar Park in North Devon; I do hope that the output from the park will not be curtailed! Toodles.

That Derrilwater site is highly contentious @toodles 

It's recently been acquired by Ripple Energy.
The original Decision Notice for planning application 1/0249/2021/FULM was made in favour of RES in Nov'21.
Work was scheduled to start in March this year.

In June'24 RES made a fresh Planning Application 1/0514/2024/FULM for a Battery Energy Storage System.
It was refused a week ago, but is likely to go to appeal.

Both the solar-farm and the BESS are adjacent to Pyworthy Bulk Supply Point, which is a 132kV node on the Distribution Grid in NW Devon.

Pyworthy is midway between the Grid Supply Point at Indian Queens in the centre of Cornwall, and the GSP at Alvediscott, near Bideford.

The 132kV line and the adjacent 400kV line are heavily oversubscribed for generation from renewable sources.

Pyworthy BSP has 137MVA of supply capacity, and 183MVA of reverse capacity for generation/storage assets.
Of that available 183MVA reverse power, it is already oversubscribed by more than 20MVA. 😲 

It will cost many £millions for NGED to reinforce their 132kV Distribution Grid,
which won't solve the problem anyway because there's no spare capacity to accept further export to the 400kV transmission network.

Not only does the future generation at Hinkley-C constrain what can be exported from the 400kV loop through Devon & Cornwall, but both the Celtic Sea wind turbines and Xlinks marine cable from Morocco are both targeted at the same GSP in the hamlet of Alvediscott.

The Planning Application 77576 by White Cross for the Celtic Sea array has just completed its public consultation phase.
It has attracted a massive list of objections.

From a purely technical viewpoint, I wouldn't be investing in any more generation or storage in this area.
The companies involved will be battling DESNZ and NESO in an attempt to make their case on political grounds.

These applications aren't based on good science.

@transparent Thank you @transparent, doesn’t sound very promising to me; we have been told that generation is due to start during the winter of 2024/2025. Toodles. 🤔 

No... it's certainly not promising if you're wanting to export power elsewhere in the UK.

From the other viewpoint, it's a great location for some commercial/industrial operations with very high demand.
Data factories and AI Research companies should be beating a path to the doors of the two local councils, North Devon, and Torridge.

Here's an ANM plot for Pyworthy, which predates RES' proposals for Derrilwater Solar Farm.

That's screaming out at me "don't build any more solar farms near here"!

Certainly for battery charging against forecast, all systems need a little fine tuning to get them reliably forecasting and charging. I ditched home assistant and GivTCP for this purpose, because even after a lot of time getting Solcast right on most days, GivTCP didn't get it right.

Now using Wonder Watt, way easier to set up, get the charge rate correct, everything setup in one app.

I've started to think, if I get run over by a bus will the system keep working without intervention from my wife. So have moved to pure WC on heat pump, zero faffing about once tuning is done. Simple battery management. Pretty low electric costs. Could maybe save a few pounds, but live is too short.

Posted by: @johnmo

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I've started to think, if I get run over by a bus will the system keep working without intervention from my wife.

I hadn't realised that being run over by a bus was regarded as a statistically-relevant parameter when calculating the ROI for solar-panels.

You should move to a rural village.

You're lucky to see a bus once a week...
... and time itself goes slower.

Here in the rural wild West Country, we're not going to need as many public EV-charge points as originally supposed.
By the time we'd 'ave got'em installed everyone would be summoning autonomous pods on demand.