It’s the 25th of May as I type away at the keyboard. Not only does the date represent seven months to Christmas day, but it’s also seven days to the commencement of the annual solar danger zone. Yup, that’ll be almost exactly three weeks out from the winter solstice. For six weeks the sun will be at it’s nadir position in the sky over Fernglade Farm. A troubling time where the sensitive soul wonders each day what solar electricity gifts that big ball of fusion reactor in the sky will supply. From time to time, it ain’t a lot.
For the three weeks either side of the winter solstice, getting a full charge into the house batteries from the solar photovoltaic panels can be a bit of a dicey proposition. At times, despite your best efforts with energy conservation and marshalling of resources, you just plain old run out of charge in the batteries due to a lack of sunlight. That’s when the trusty old Honda powered generator gets wheeled into action.
Generators are a funny kind of machine. The big one used here is rated at 3.4kVA, otherwise described as 3,400W, which is a lot more than you can draw out of a mains electricity connection. Except generators have this weird thing called a ‘power factor’ (whatever that means), and on this machine it’s listed as 0.8, which bizarrely means that in reality it will only supply about 2,800W, which is plenty for my needs.
The generator uses uses the energy source of petrol to produce mains electricity, which is then sent into a battery charger. Those are also a funny kind of machine. The battery charger takes the mains voltage from the generator, and converts it into a form that the depleted batteries can absorb. All very simple, except you get the impression that the powers that be don’t generally trust the average household wiring. Off the shelf large battery chargers generally have their output limited to about 1,500W.
Serious people suggest that the theoretical energy in a litre (about a quarter of a gallon) of petrol is about 9,000W. But with all of the losses, only 1,500W of that theoretical energy gets sucked into the hungry batteries. The rest of the energy turns into friction, noise and heat. It’s a seriously noisy machine. And I’d suggest that the powers that be are probably correct to limit the output of off the shelf large battery chargers, because after a couple of hours, even the cables are warm to touch. Three hours run time is enough noise for me, and a break allows the electrical equipment and cables to cool down.
By contrast, when conditions are ideal, the solar photovoltaic panels can supply between 7,000 and 8,000W! The batteries are totally unfussed by receiving so much electricity. It’s worthwhile mentioning at this point, I’ve spent a lot of time and resources over the years, so as to ensure that all of the components and cables in the power system run cool. Every last component, and there are an awful lot of them. Nobody ever wants to see a power system emitting magic black smoke, although that has happened here once or twice in the past. A minor failure which produced a salient lesson.
Anyway, enough of the background details, the truth of the matter is that I simply don’t like running the generator. Originally it was my belief that the system would work in all conditions. Reality is otherwise mostly because the sun has it’s own plans. Years ago a state of acceptance was reached, and nowadays I’ve been beaten down by reality. Thus the petrol generator gets wheeled out, started up and plugged in. Life goes a whole lot easier with acceptance.
I do wonder if people with political stripes promoting this technology have actually lived with it? Hard to know really, and I’m way too busy to be bothered asking them. It’s probably not a bad question to ask though. Anyway, my perspective on the technology nowadays is that: it’s good, but not good enough to power an industrial civilisation.
Thought you lovely readers might be interested to see some of the statistics I’ve collected on the real world performance of the off grid system here over the past five years (remembering that winter begins in June whilst summer begins in December):
The statistics reveal an interesting story. At this location, 82% of the year (or 299 days) the sun provides all of the electricity we require. For another 16% of the year (or 58 days) the sun does not provide enough electricity, and so to make up the difference we’ve drawn down on the reserves in the house batteries. Finally, over the past five years, we’ve run the generator to put some charge into the batteries on 40 occasions, or that’s an average of 2% of the year (or 8 days each year). It’s not hard to notice that the worst month for solar power production, also happens to coincide with the winter solstice. Can you imagine households dealing with no electricity for 8 days every year – that’s the future, right there.
Some people might suggest to simply add more solar panels, and that might work. I’m not interested in that option, mostly because dealing with the additional energy when the sun does shine again, can bring new and interesting problems with the various components in the system. It’s not often discussed with conversations relating to solar derived electricity (mostly because in the media they’re deliberately dumbed down), but each and every component in the system has hard upper limits as well as constant limits, and you change one thing anywhere in the system, and there are consequences. The old timers used to have a saying to: Best let sleeping dogs lie. Wise words.
The data is very useful to record, and you get to develop a feel, in detail, as to how the system should be working. Each day the system is checked both morning and night (and sometimes during the day), and last week the readings weren’t meeting my expectations. Turns out that with the sun lower in the sky now, the two olive trees in the courtyard were over shadowing about eight solar panels. If there’s one thing solar panels don’t respond well to, that’s shade of any description.
We purchased the olive trees at a local clearance sale many years ago, and they’ve grown huge. They were a great purchase and clearly conditions are suitable for the trees. Here’s a view from a different angle:
It’s far easier to prune the big old olive trees, than to move eight solar photovoltaic panels. I grabbed the trusty old Stihl mains electric pole saw. It’s a powerful beast of a machine, and made short work of the job. Pruning just one of the trees produced a humongous pile of olive branches which we’d intended to chip up into mulch.
By the time the second olive was pruned, there was so much material in the courtyard that we decided instead it would be easier to simply burn the whole lot off in the brazier – which was conveniently also located in the courtyard. By the next day, all that was left was a pile of ash, and two thoroughly pruned olive trees.
Many things you will now see in the above image, but overshadowing of solar panels is however, not one of those things!
Observant readers will note that the rock wall surrounding the olive on the left hand side of the above photo, has barfed up all of it’s rocks. We dismantled the rock wall because it was inadequate, and had collapsed. The rocks used in that wall were simply too small (the wall was constructed long ago, and Peak Rocks has long been a problem here).
On another day, we brought uphill all of the large rocks created from split boulders last week. They were dumped near to the olive trees.
It took a lot of hours, but the rocks were carefully placed and manoeuvred so that they formed a nice new circular rock wall surrounding the olive tree. It’s quite solid and now exactly matches the dimensions of the other olive tree rock wall.
This week’s video was on this subject:
Whilst we were doing rock work, all of the piles down below at the forest edge were cleared. Those rocks were all brought back uphill and used in various projects.
The steel gabion cages to the uphill side of the shed, are rapidly filling. In the above photo with the completed rock walls around the olives, you can see the gabion cages in two layers at the left hand side of the shed.
Many mid-sized rocks were also placed around the terraced garden beds fence because rabbits had burrowed under it. They won’t be able to burrow under rocks now though! Sadly by the end of that work day, we had yet again run out of rocks. Peak Rocks is real, you read it here first.
And just because we hadn’t done enough work this week, another day of forest clean up took place. Ollie enjoyed cooking his head by the bonfire in the cool evening air.
The fire looked quite impressive at night, and as a bonus for doing that good work, we discovered that there were a whole lot of useful sized rocks in that now cleaned up area. Peak rocks has been averted, for the moment.
In breaking produce news:
We had our first frost of the year this week. It sure felt cold on two mornings in particular.
Other mornings, fog has hung over the valley. One day the sky looked as if it was almost merging with the land. The sky and fog was a lovely blue colour:
Oh, and we harvested four very tasty sweet purple figs from a three year old tree:
And the Loquat tree has finally produced some flowers. That tree is well over fifteen years old and now quite large. Loquats are tasty fruit, but you won’t generally see them for sale because they are soft and don’t tend to travel well:
Onto the flowers:
The temperature outside now at about 10am is 10’C (50’F). So far for last year there has been 208.2mm (8.2 inches) which is up from last weeks total of 206.8mm (8.1 inches)