PV Yield Support Group - with a hint of Prepping. :-)

Just three more weeks of diminishing yields then it is winter solstice and presumably it would get better thereafter! This is the first year that I have had PV and wow, the angle of the sun as well as the length of day is devastating.

Things I noted:

  1. Timers on geysers can’t really be static throughout the year. My peak (albeit diminished) moved so far by almost 2 hours.
  2. If I get more batteries, I’ll have to carefully manage them, because it will get much more difficult to get them nice and full (I can definitely see myself turning on battery life, or do something external by limiting the inverter power)
  3. West panels is really nice when the angle of the sun is good, but the angle I’m dealing with now - They really do struggle (still nice, but not nearly as nice). The North ones does seem to lose less.
  4. Colder “cold” water and hotter and longer showers (probably for comfort) does make my geysers run much longer. So far observing about 50% increased time (not scientifically measured). This will also cause me to have to adjust the timers a little to ensure no domestic disputes.

From the thread title I was expecting you to begin with:
“Hi, my name is jykenmynie and I’m addicted to watching my PV system yield.”
Then we would all reply with “Join the club”


Well that is also true by implication of the contents of my post… :smiley:

Took me just over a year but I saw in the middle of winter, on a sunny day, I need 500w more … 4.2kw total … to charge the batts and power scheduled loads.

Nor do I fret the weather winter days in Cpt cause there are some cool winter days making up for some of the bad days. For in summer one “makes a lot of hay”.

Win some loose some. Relax, have a beer.

“Hi, my name is TTT and I’m addicted to watching my PV system yield.” :laughing:


Hi TTT, welcome. This is a safe space to talk about your addiction.


AAA so nice to feel “cared for.” What would one do without this support group!!! :laughing:

Truth be told, I need to make time for NodeRed cause this nonsense of the batts and cloud cover, must be done away!

I KNOW Victron does a sterling job but maggies man, “dis GROOT amps wat loop” when the cloud cover moves in, moves away, moves in, moves away … hour after hour, day after day … and this winter, week after week.

Throttle the inverter to max PV input as @Paul has done, my next move, using HomeAssistants NodeRed. The Cronjobs and SOC increase I run currently works like a charm in summer, maar nou is ek gatvol. :wink:

So my automation does a really good job at this. I limit the inverter to the PV production while the battery is still empty, and when the battery is full, I switch the system over the “Keep Batteries Charged” until sunset. At sunset I put it back on “Optimise” and limit the inverter’s power to 250W. The 250W is current an input in my Home Assistant UI, but I plan to make it “automatic” once I understand the whole thing a bit better. Probably going to end up calculating it as follows: min(battery’s remaining capacity to X% SoC / time to unrise , 500W).

Congratulations on taking the first step to recovery, admitting you have a problem.

Also not having a lot of fun with yield these past few days. Going to have winter/summer timers going forward and will need to build in a few more rules to manage these cloudy/rainy events… Considering to add a few more panels maybe, I will be clipping in the summer for sure, but early mornings and late afternoons I could also benefit from them at least and obviously in bloody winter!

The big thing that is working for me is to “track” the battery discharge vs the panel output.
If the batteries are discharging you can be pretty sure that you have reached the maximum output of your panels and as a result, you can adjust the power limit accordingly. That way you should almost never discharge your batteries at a high rate and if the panels output is lower than x amount then set discharge to a fixed value.
In my case, what would the average discharge be for my batteries to be at x% in the morning regardless of the consumption? It is way better to discharge your batteries at an even rate than to hammer them to 20% in three hours.
You also have the added benefit that you are not reliant on a timer. If there is enough sun available you will use it to its full potential.
Another thought is , you do not need to charge your batteries to 100% every single day, obviously, it will be bad if you leave them discharged for a week or two but we seldom have such bad weather and also Victron does have a safeguard against discharging them too deep constantly.
If it takes the whole day to charge them to 80% (as a result of baddish weather) or if you first charge them to 80% and then use the solar the net result will be the same.

This obsession to optimise your system goes with the territory.
I have a theory that every RE enthusiast has a dream to go off grid.
This is crazy. Going off grid is in another league…

Hi all, my name is EbenDL and I am an yieldaholic.

Actually I had this realisation last winter already – when my batteries didn’t fully charge during the pale highveld winter sun. At that point I got another 6x310W panels and now it works well enough that I can still run my geyser a bit from the PV in the afternoon.

That being said, with the rain and cloudy day we had in PTA today absolutely nothing happened…

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Exactly what I’m trying to optimise: Get my battery to X% SoC over the night, but do so in an orderly fashion and not by ramping up the temps through high current discharges.

So far it is working very well, albeit a bit manual to set the maximum inverter power after sunset (the setting is done automatically with Home Assistant, bit choosing the maximum inverter power to set it to is an input). Due to changing lengths of night it needs fine tuning every two weeks or so. I already have a good idea how to automate it, but I want to observe it first for a while to work out the kinks in my thinking.

My issue is I don’t really have roof space left before I don’y move my black pipes for heating the swimming pool… :tired_face:

Maybe the whole country will be off grid soon if the power collapses :laughing:
But you right, I’m definitely working towards off grid and maybe sooner rather than later. IF planned correctly I don’t think its crazy but I guess it depends on each households needs.

Going off grid means “usage compromise” rather than “additional PV panels”. Firstly because there will be horrible days, but mostly because then you need like at least 10kVA inverter ability to be safe (in my own case) and a much larger battery bank.

So “usage compromise” is much cheaper and more practical.

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yeah 100%
so instead of running your dishwasher after dinner, you have to load and only switch it on the next morning after breakfast. So its just getting into that type of energy saving frame of mind. We have checked our usage and by putting one bathroom on a gas geyser we can basically run all other loads during the day and have average of 300-500W going throughout the night which means we need maybe one extra battery.

I set my MaxInvOutput based on SOC and Time using NodeRed. @ 16:00 it drops anyway AND @ 50% SOC at any other time. I am a bit “thin” on batteries so don’t want push them to hard.

By definition they will be off-grid. The question is whether they will be on-something-else? :slight_smile:

The hard reality of this eventuality is that if that happens, there will be chaos. You had better have some canned food in the garage and enough water to drink. Supermarkets will run empty within days. Filling stations too (because the refineries aren’t running). Sewage plants will stop running and overflow, reservoirs will likely run empty (Cape Town has some contingency plans in place for this, but many places don’t). Communications will die as the backup power runs out at the various nodes.

My advice would be that if such a thing happens, and you have the possibility of staying with someone in a rural area (with their own water), or if you can get on a plane and go somewhere, or move to a neighbouring country… that would be the smarter thing to do. It doesn’t help to have your own power. You also need your own water, and enough stored food and fuel. A satellite uplink would be nice. Possibly even a firearm, although I don’t want to be a doom-and-gloom prophet :slight_smile:

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You make it sound like fun! At least much more eventful than my typical day of coding projection models for life insurance companies.

I have a borehole but will have to do rewiring to get it on the panels. Also do not have a tank for storage, so pretty much screwed already I guess.

Also no backup food.

Perhaps worthwhile to get Starlink… oh wait: Bad news for Elon Musk’s Starlink in South Africa (mybroadband.co.za)

Of course the trouble with getting into a neighbouring country is that right now you need a PCR test for that (Namibia no longer accepts rapid test, perhaps that will become available again in future, I’m unsure about Botswana). So that stops working the moment the labs stop working…