Outgoing Octopus

[Joeboy]

Is the aim here a system test/stretch and 72×3×15p less any overnight costs?

There will be no overnight costs, this is to see if I can export for 3 days (and nights) at 3kW without interruption or any grid support and still power my house. I could make more money by exporting at higher export rates in the day and charge overnight on the cheap slot.

But this is a personal record stretch test of my system and as an aside, I want to show just how far solar farms and batteries can power the grid. We can all do the maths theoretically but doing it for real is something else.

All the best in it. Look forward to reading the results.
I hope your cables stay cool.

[Joeboy]

We have managed at absolutely no cost to ourselves to export over 10kWhs today. Yes it would be great to be paid for today but strangely I'm not bothered.

It feels good to be doing a clean beneficial thing. I wonder how far the electrons got and what they powered in my area?




I'll see what a month does for a export figure on a largely un used system.

[nowty]

We had some heavy cloud around midday but that was expected, some high cloud coming later but looks thin on the satellite images so I'm quite bullish in keeping 3kW+ solar generation till around 7pm.

Batteries back to around 97% now so ramping up the export to 6kW to keep the DC charge controllers in business.

[Joeboy]

We had some heavy cloud around midday but that was expected, some high cloud coming later but looks thin on the satellite images so I'm quite bullish in keeping 3kW+ solar generation till around 7pm.

Batteries back to around 97% now so ramping up the export to 6kW to keep the DC charge controllers in business.

Nice, sounds like you're sorted for the first night. I'm going to collect daily info on export on the Goodwe and check the total tallies with export meter at home mid Aug.
13.1kW Xp today.

[nowty]

Power is really dropping off now with high cloud, 14hrs or so of discharge till I regain decent solar power again.

My 3kW export plus the house its a 3.5kW power drain x 14hrs = 49kWh.

Battery is going to be low low low low low by tomorrow morning.

[Joeboy]

Power is really dropping off now with high cloud, 14hrs or so of discharge till I regain decent solar power again.

My 3kW export plus the house its a 3.5kW power drain x 14hrs = 49kWh.

Battery is going to be low low low low low by tomorrow morning.

Do you have a cutoff percentage for soc or winging it in this the 1st night with real weather scenario?

[nowty]

Do you have a cutoff percentage for soc or winging it in this the 1st night with real weather scenario?

Unfortunately because its a bodged system running different chemistries of lithium then run as Lead Acid to fool the Sunny Island I cannot do SOC via the Sunny Island because it just thinks they are always 70%+ SOC. But I can set a min voltage which I set to 47V, at that point the sunny Island will just bring in grid power to make up any shortfall from the batteries.

The first stage cutoff is a DC relay which cuts the Pylontechs (LFP) out of circuit when they are around 10% SOC. Even if this fails to work they go into error mode and shut down around 5% SOC by themselves.



Then the 10 LMCO banks (reused second hand growatt batteries) keep running until they drop to 47V which is still around 20% SOC because I don't want them to get too low.

The whole lot gross capacity is over 70kWh, but useable probably about 55kWh to 60kWh. Some of the growatt batteries must be a decade old now but I don't see any loss of capacity.

So if the batteries do get down to 47V overnight, nothing bad will happen apart from the 3kW export will drop until its just importing enough power for the house at peak leccy grid price.

[nowty]

Progress on my day 2 out of 3 day continuous exportathon,

Still some high cloud here this morning but we have got to around zero battery discharge at 9.30am and I reckon I used about 44kWh out of the battery overnight and the voltage has dropped to 49.7V so about 25% SOC.

Tomorrow looks epic with wall to wall sunshine all day but today looks similar to yesterday. But more kWh's than yesterday is needed to go back into the battery so and I need to get the battery stack back up to around 53.5V (75% SOC) to have a chance of making it through tonight again.

Yesterdays effort - Day 1 exported 81kWh with a continuous minimum of 3kW.

[nowty]

Day 2 – Exportathon progress.

Sun has been absolutely banging here most of the day and batteries have peaked at around 85% SOC just after 6pm, that should be enough to keep the wolf from the door overnight and continue the 72 hour exportathon. Tomorrow looks like getting decent sun an hour earlier and its sun, sun, sun, all the way.

Only a power cut or a hardware failure Can Stop Me Now.

[Joeboy]

That is excellent,I'll try 07.00 to 17.00 and see what we get. Weather app says a decent day in the shire. Starting at 77% soc.

Are you stopping at 3 days or rolling through to season end?

I hope to hit 20kWh export which is half the stack. Beyond that it's a learning curve.