Earth Notes: On Website Technicals (2021-04)

Updated 2021-04-10 15:56 GMT.
Tech updates: Ds are good, more tweets vicar?, Ds are fiddled with, moar, less...
Will be keeping an eye on making the most of my off-grid energy again...

2021-04-10: Less Dumping

Dull day today: will maybe have pulled ~150Wh off-grid, and the big array has not floated over Vmpp so far. (The grid-tied system had generated ~4.6kWh by ~16:00Z, vs 14.9kWh yesterday, for reference.) The dump load has been operating maybe 50% of the time.

So it seems possible to absorb everything available with the current setup.

2021-04-07: Moar Dumping

Looking at all times in April up to ~6pm BST today where the panels have been floating over Vmpp, and dumping wasn't happening, shows:

cat /var/log/powermng/2021040?.log | awk '$23>=30000 && $14!="D"{print}'
2021/04/01T10:20:06Z AL 3528 B1 14271 B2 -1 P 2070 BV 14144 ST VH - s A1P 50324 B1T 16 UC 100 A1V 31577
2021/04/05T08:10:06Z AL 1380 B1 13007 B2 -1 P 14464 BV 12679 ST OK - s A1P 17847 B1T 11 UC 100 A1V 30323
2021/04/05T09:50:06Z AL 2624 B1 13227 B2 -1 P 15119 BV 12889 ST OK - s A1P 34712 B1T 11 UC 100 A1V 30619
2021/04/05T10:00:06Z AL 3863 B1 13727 B2 -1 P 2966 BV 13635 ST H - t A1P 52785 B1T 11 UC 100 A1V 30127
2021/04/05T10:10:06Z AL 4228 B1 14185 B2 -1 P 2100 BV 14030 ST H - t A1P 59700 B1T 11 UC 100 A1V 30509
2021/04/05T10:20:06Z AL 2556 B1 13846 B2 -1 P 4016 BV 13714 ST H - t A1P 35512 B1T 11 UC 100 A1V 30274
2021/04/05T16:40:06Z AL 1088 B1 14094 B2 -1 P 3214 BV 13995 ST F - t A1P 876 B1T 12 UC 100 A1V 33069
2021/04/05T16:50:06Z AL 431 B1 14090 B2 -1 P 2424 BV 13934 ST F - t A1P 6734 B1T 12 UC 100 A1V 31934

No missed opportunites since the last algorithm tweak. Today and yesterday have been mixed sunny/overcast.

A more general look at all times floating over Vmpp so far in April shows 215 samples or ~36 hours (out of ~162 hours) where available energy was not being fully used from the off-grid system (including the 12V-nominal part):

% cat /var/log/powermng/2021040?.log | awk '$23>=30000{print}'
2021/04/01T10:20:06Z AL 3528 B1 14271 B2 -1 P 2070 BV 14144 ST VH - s A1P 50324 B1T 16 UC 100 A1V 31577
2021/04/01T10:30:07Z AL 2969 B1 14271 B2 -1 P 2141 BV 14144 ST VH D e A1P 42367 B1T 16 UC 100 A1V 32676
2021/04/01T10:40:06Z AL 4433 B1 14298 B2 -1 P 16100 BV 14074 ST VH D T A1P 63430 B1T 15 UC 100 A1V 31809
2021/04/01T10:50:06Z AL 3871 B1 14301 B2 -1 P 17662 BV 14074 ST VH D h A1P 56786 B1T 15 UC 100 A1V 33054
2021/04/01T11:00:06Z AL 2759 B1 14267 B2 -1 P 13697 BV 14004 ST VH D h A1P 41703 B1T 16 UC 100 A1V 33671
...
2021/04/07T15:10:06Z AL 1658 B1 14496 B2 -1 P 15178 BV 14118 ST VH D A A1P 24687 B1T 9 UC 100 A1V 33219
2021/04/07T15:20:06Z AL 1745 B1 14496 B2 -1 P 14960 BV 14118 ST VH D A A1P 25517 B1T 9 UC 100 A1V 33967
2021/04/07T15:30:06Z AL 1665 B1 14499 B2 -1 P 15311 BV 14179 ST VH D A A1P 24158 B1T 9 UC 100 A1V 32871
2021/04/07T15:50:06Z AL 1701 B1 14493 B2 -1 P 15175 BV 14170 ST VH D A A1P 14903 B1T 9 UC 100 A1V 32554
2021/04/07T16:10:06Z AL 2109 B1 14493 B2 -1 P 15378 BV 14223 ST VH D A A1P 8818 B1T 9 UC 100 A1V 33149

The maximum that that could have represented (an unrealistic upper bound) is ~500W * 36h = 18kWh, or ~2kWh/d. Very likely the excess energy most of the time, except with bright sunshine direct on the big panels unshadowed near noon, is a small fraction of that. The fact that I have been able to run a ~100W water heating load without the system batting an eyelid suggests that significant money is definitely being left on the table though!

Indeed 205 out of the 215 samples are with battery state of HIGH, VHIGH or FULL, so likely far from marginal excess available.

In principle I could craft a hardware dump to bleed off all energy above Vmpp, ie keep the voltage down to ~30V, and measure what energy is dumped that route.

2021-04-05: Dumping Setup Is Tweaked

Spoke too soon! This short dropout stopped dumping at a key time (16:30Z):

2021/04/05T16:10:06Z AL 1404 B1 14094 B2 -1 P 14644 BV 13758 ST F D F A1P 19674 B1T 12 UC 100 A1V 33085
2021/04/05T16:20:06Z AL 1595 B1 14060 B2 -1 P 15930 BV 13776 ST F D F A1P 22316 B1T 12 UC 100 A1V 30271
2021/04/05T16:30:06Z AL 805 B1 13413 B2 -1 P 14688 BV 13109 ST OK - s A1P 8939 B1T 12 UC 100 A1V 28574
2021/04/05T16:40:06Z AL 1088 B1 14094 B2 -1 P 3214 BV 13995 ST F - t A1P 876 B1T 12 UC 100 A1V 33069
2021/04/05T16:50:06Z AL 431 B1 14090 B2 -1 P 2424 BV 13934 ST F - t A1P 6734 B1T 12 UC 100 A1V 31934
2021/04/05T17:00:06Z AL 764 B1 14090 B2 -1 P 3269 BV 13951 ST F - t A1P 10675 B1T 12 UC 100 A1V 29517
2021/04/05T17:10:06Z AL 677 B1 13965 B2 -1 P 3073 BV 13793 ST F D F A1P 9407 B1T 12 UC 100 A1V 27594
2021/04/05T17:20:06Z AL 595 B1 13199 B2 -1 P 12988 BV 12942 ST OK D T A1P 7837 B1T 12 UC 100 A1V 27591
2021/04/05T17:30:06Z AL 474 B1 13163 B2 -1 P 12282 BV 12881 ST OK D E A1P 6161 B

And in fact the day before at much the same time, FULL dips to OK once:

2021/04/04T16:20:06Z AL 1351 B1 13648 B2 -1 P 14290 BV 13425 ST F D F A1P 18421 B1T 12 UC 100 A1V 27732
2021/04/04T16:30:06Z AL 1409 B1 13852 B2 -1 P 15362 BV 13547 ST F D F A1P 20550 B1T 12 UC 100 A1V 29056
2021/04/04T16:40:06Z AL 1100 B1 13431 B2 -1 P 14869 BV 13109 ST OK - s A1P 14812 B1T 12 UC 100 A1V 28025
2021/04/04T16:50:06Z AL 810 B1 14090 B2 -1 P 3072 BV 13951 ST F - t A1P 10177 B1T 12 UC 100 A1V 28913
2021/04/04T17:00:07Z AL 687 B1 13877 B2 -1 P 3026 BV 13688 ST F - t A1P 9498 B1T 12 UC 100 A1V 26462
2021/04/04T17:10:06Z AL 602 B1 13736 B2 -1 P 3654 BV 13574 ST F - t A1P 8184 B1T 12 UC 100 A1V 26175
2021/04/04T17:20:06Z AL 588 B1 13617 B2 -1 P 2969 BV 13468 ST F D F A1P 7942 B1T 12 UC 100 A1V 26127
2021/04/04T17:30:06Z AL 474 B1 13172 B2 -1 P 14674 BV 12907 ST OK D T A1P 6191 B1T 12 UC 100 A1V 25733
2021/04/04T17:40:06Z AL 389 B1 13120 B2 -1 P 14590 BV 12863 ST OK - s A1P 5104 B

This may even be a bug/feature in the charge controller.

Unwanted brief 16:30Z/16:40Z dropouts that would be better ridden through.

So I've moved the 's' case directly below the 'r'ide-through case (they were the other way round) to try to avoid extended dropouts from the sun briefly going in (or a controller 'feature').

This would have been a good moment to continue grid support, and this possibly lost the opportunity to pass 40 minutes of sun to the load.

It is possible that the ride-through period should be reduced from the current 40 minutes.

2021-04-04: Dumping Setup Is Good

I'm reasonably happy from examining when the large PV panels are being allowed to float above Vmpp (maximum power point) that I'm dumping ('D's, taking load off-grid) whenever I reasonably might.

Vmpp seems to be just short of 30V (on colder mornings). Looking at times when the array voltage has been allowed to float above that, but the system wasn't dumping, shows only one 10-minute slot in the first three days of April with mixed/sunny weather:

% cat /var/log/powermng/2021040{1,2,3}.log | awk '$23>=30000 && $14!="D"{print}'
2021/04/01T10:20:06Z AL 3528 B1 14271 B2 -1 P 2070 BV 14144 ST VH - s A1P 50324 B1T 16 UC 100 A1V 31577

I will resist the urge to tinker with the power management code for now.

Energy harvested off-grid since restoring the router dump-load on the 28th has risen from ~150Wh/d to ~300Wh/d:

2021-03-24 0.1 0.168
2021-03-25 0.1 0.170833
2021-03-26 0.2 0.173913
2021-03-27 0.1 0.177273
2021-03-28 0.1 0.180952
2021-03-29 0.3 0.18
2021-03-30 0.4 0.184211
2021-03-31 0.2 0.188889
2021-04-01 0.3 0.194118
2021-04-02 0.3 0.2
2021-04-03 0.3 0.2

Auto-tweeting

Also today I set up a mechanism (via the existing intensity Twitter poster) to be able to send additional tweets ad hoc.

I'm using this to emulate what I currently do semi-manually with Hootsuite, ie send one article tweet during the day, and one down-under-skewed tweet in the small hours of the night (thus antipodean daytime).

The down-under tweak is to pick featured articles 6 months out of sync, to pick up more that are seasonal for there.

Articles selected are featured for the current month (or 6 months off), popular, or a few randoms (that are not noindex).

My Java Twitter connector is old enough that it thinks tweets are limited to 140 characters: I should upgrade that to allow longer tweets including the page description.