Idea

fish suggested Jun 14, '23

Venus OS/Node Red which changes ESS SOC% based on daily forecast.

Hi,

New to Node Red but wanted to programme the ESS in Venus to set the SOC each night to take advantage of a duel tariff between 00:00 and 04:00, quickly realised you need to be able to forecast the solar expected.

Anyway I've written and used two other peoples flows so that his checks both Solcast and Forecast.Solar for the next day, takes an average from Solcast(foundit tends to over estimate) and then avergaes again between the two.

It then sets the SOC % based on this forecast, the months ie. season and then returns it to my normal 15% when it gets to the end of the tariff window.

It also emails me with what figures it has used and settings.

You will need to read through and understand how it works, and it will require your own settings and API accounts with Solcats, and Forecast.Solar. You will also need an smtp for the email, I'm using gmail(you will need to add the device as no modern auth)

While there is alot to get your head around it has been working faultessly for me for a number of months now and only got my forcast really wrong once!

I hope this is useful to people as I couldn't find a full solution when I lucked and any questions please ask but I'm not that skilled as new to this. Any comments or improvements please share.

Cheers

James

JSON uploaded as txt, you will need to change file extension to JSON to use:

14_06_23 Public.txt

red-node.jpg (446.6 KiB)

14-06-23-public.txt (88.2 KiB)

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fish commented Jun 14, '23

Whoops maybe this should be an article rather than idea, if an admin could put it in the right place that woudl be great. Thanks

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fellside commented Jun 14, '23

Hi fish

Great to see this, probably what a lot of users have been looking for.

I'm a bit of a Node Red novice so my question may be easily answered,

I have installed the flow and are part way through settling it up (and understanding it)

Node red is coming up with the following

Flows stopped due to missing node types.

calculator
e-mail
moment

Any idea where I can find these nodes or can you add them to the flow download?

Thanks

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fish commented · Jun 15, 2023 at 09:54 AM

If you go into palette manager from the drop down on the right and search for calculator etc you need to install the following:

node-red-contrib-calc

node-red-contrib-moment

node-red-node-email

The nodes which are red lined will now appear and work..

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fellside commented Jun 14, '23

Hi fish

Ok I`ve sorted that problem :)

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fellside commented Jun 19, '23

Hi 
I have run your flow over the last couple of nights and now have it working and returning emails.  
I have Forcast Solar and Solcast running in Home assistant and the give the following forcast for today 
FC 19873 
SC 21010 
So the average shown in the quoted email below is a bit low. I am at the moment having a problem getting Solcast to answer the Flow when called. 

What setting do you suggest for the High, Mid And Low SOC. Max generation here at mid summer is 24kWh/day  
You asked for improvements, suggestions. Make it easier for the user to set the start and finish times to suit their over night tariff.  

Email received this morning  
“Node Red used an average of 10264 Wh as the basis of the ESS charge setting change.   ESS SOC was set to: 65   Forecasts used were:    - Forecast Solar: 10264 Wh.      - Solcast: undefined Wh (Average of: Estimate undefined Wh & Pessimistic undefined Wh ) “  

No charge carried out as minimum system SOC was around 75%  

Many thanks

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fish commented · Jun 20, 2023 at 07:17 AM

Yep looks like the Solcast isn't happy. I ended up using both Solcast and Forecast.Solar as they sometimes vary alot. I'm sure you'll egtt he solcats going.

I like the idea of a better time selection, I did look into it but at the time it seemed quite complicated as node red is on local and the charge times are GMT, I might investigate the issues are the forecast needs to be donethe day before as the flow takes the next days forecast. Even that coudl eb tightened up I suppose.

As regards SOC levels I'd imagine it is trial and error I set them based on my 51kwh ESS with 12kw PV after a bit of trial and error, I imagine it will keep changing as I have different electrical uses. I'm just about to fit A/C so will use more so it will change again. Just remember there are three areas; The season months, what constitutes high low med SOC and the resulting % to set the batteries at.

Have fun.

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pau1phi11ips fish commented · Jun 20, 2023 at 10:33 AM

Your system is almost 10x bigger than mine! lol

Currently 1.4kW of solar and 7kWh of storage. There's been a few days this year where the solar's covered all our power (use 7-10kWh/day). It's rare that we use much grid power outside of the cheap 4 hours I have at night to charge the battery.

Thanks for sharing the flow. Looks really interesting!

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fellside commented Jun 21, '23

Hi fish

Ok I have it all working now. Email received this morning

"Node Red used an average of 18696 Wh as the basis of the ESS charge setting change.

ESS SOC was set to: 45

Forecasts used were:

- Forecast Solar: 20399 Wh.

- Solcast: 16993 Wh (Average of: Estimate 22406 Wh & Pessimistic 11580 Wh ) "

I am finding Forcast and Solcast Estimate are pretty close to what I get. Solcast Pessimistic (P10) is quite a bit out, so drags the average down.

So I can now get on with tuning it for my location.

Thanks for sharing this flow.

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fish commented · Jun 21, 2023 at 08:40 PM

I occationally get a totally off forecast day from both providers and run out but it has only happended twice this year! You just need to vary it for your particular setup...

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fish commented · Jun 21, 2023 at 08:55 PM

Also I noted out of the main Summer season the two forecast can vary quite a bit hence why I averaged them..

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Jean-Pierre PALMAS commented Jun 29, '23

Hello, I am in France so the off-peak hours are different, but the principle remains the same.
I just have a problem with the Solcast API which systematically returns me a "parse error" on the json file!
When I test the HTML link on a browser, my file is good, but apparently not on the Solcast AP I!!

Do you have an idea to solve this problem? Thank you so much.

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fellside commented · Jun 30, 2023 at 09:56 AM

Are you placing you Resource Id into the ULR field

https://api.solcast.com.au/rooftop_sites/Your Resource id?format=json&hours=72

Put the API key in the in the username field. Password field is left blank.

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fish commented · Jun 30, 2023 at 01:04 PM

Sorry I really am new to this, it woudl be worth reading the Solcast documentation for API and go through what you have typed in. It is reasonably straight forward and I can only believe it will be a slight typo.?

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fellside commented Jun 30, '23

I have a problem. I wonder if you can have a look.

My Solcast installation in Home Assistant is working well and I have it adjusted so it gives a fairly accurate forecast. So using the information from HA.

I have noticed that your Forecast flow seems to be using the day after tomorrows Solcast forecast. Flow poles Solcast for the forecast at 23.45 and gets the today's forecast, tomorrows, D3, D4 etc. From the information in the email I am sent it is using the D3 forecast which it averages with pessimistic D10. That is why it seems the Solcast forecast is lower than Forcast.Solar. I had a series of similar sunny days and it was not until there was a low solar day (rain) that I noticed there was a difference. Forcast.Solar is reasonably accurate every day.

I may be wrong in this. I would appreciate it if you could have a look at it.

Thanks

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fish commented · Jul 11, 2023 at 04:02 PM

Thought I'd checked that as the differences stood out to me I'll re look at it?

Cheers

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Masquelier Pierre commented Jul 27, '23

For Off grid station, the forecast is also important to increase the efficiency of the power extraction.

Is it possible to swith a relais when the consume power is less than the forecast power. This function should be integrated in ASSISTANT to switch ON not essential loads (DC or AC).
Do we have enough resources in the nanopi's EasySolar II GX to make that difference in power and swith a relay? And do we have the opportunity to receive useful information from VRM with existing resources without adding anything?

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Jean-Pierre PALMAS commented Sep 15, '23

My Node-Red HTTP requests no longer work !!!

Since yesterday, my HTTP requests from Solcast and Forescast.solar no longer work!

In return I get this error:

"RequestError: connect EHOSTUNREACH 2600:9000:269a:d000:c:5e84:e340:93a1:443 : https://api.solcast.com.au/rooftop_sites/xxxxxxxxxxxxx/forecasts?format=json&hours=72"

Same for Forecast.Solar!

Has anyone had this error? and the solution to fix it?

Thank you for your help

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Spencer commented Sep 18, '23

This looks like a chunk of what I was after.

I was planning on using the data which is shown in VRM showing my actual kWh usage as historic data. I.e. my future demand in kWh is the same as the latest history. This should therefore cover seasons in that my usage will gradually change and the tool will keep up. It will of course be wrong the day after I get back from a holiday but will smooth out over time until the next holiday.

For the solar forecast I was thinking of a 2 day forecast so the decision of the overnight charge can be done as late as possible giving me the most accurate forecast and the best estimate of kWh usage around sunset of the evening before the charge.

I.e. it's using very simplistic machine learning concepts so minimal configuration.

I have node-red and home assistant running but I'm still at the beginning of a very steep learning curve regarding how to use them!