It appears that ulitities are focussing on increasing transformer voltages to compensate for line losses. Over longer LV cable runs they can be set quite high. The solar pv systems will eventually rise to the transformer setting. Has consideration been made to reducing resistence by increasing the dimensions of LV cables to reduce resistance in those scenarios?
If you're getting line losses then the line resistance is too high for the rated current. If you increase the conductor diameter you will need more copper; if you raise the voltage you will need bigger (or more) insulation. It's a trade off which I believe is why the US adopted a 110V system (copper cheaper than insulation) while Europe adopted a 240V (or thereabouts) system (insulation cheaper than copper). If solar panels 'evolve' to contain integrated inverters and MPP circuits the situation will tend to resolve as everything will be at say 240V AC and you wire it accordingly. But on some installations this may well not be the most 'cost effective' solution. It certainly may not be the safest!
I am pretty sure that overall cost is the principle and primary consideration. However value for dollar should be the basic principle not 'how much do I pay?' (going for the cheapest option) but rather 'what do I get for my money?' (going for the most cost effective option, which may not be the cheapest).
From my experience it is not the DC side of the installations, in fact not anything to do with the RE installation at all. In modern times commercial installations are heading over 600 V DC anyway.
It is the line between the grid-tie transformer/inverters and the HV/LV AC transformers in the network that seem to be the problem. The Utilties raise the transformer output LV voltage to deliver 240 V (abt) at the point of delivery. When the grid-tie inverters reach near full capacity the network line rises to its 'null' state ie that fixed at the HV/LV AC transformer.
That is my hypothesis I do not have any scientific data to support my argument. From an economic perspective, just in WA alone the cost of upgrading LV lines to reduce resistance to within acceptable interface levels would run into billions.
Further, the taxpayer would be funding an opportunity for 'freeloaders' on the grid. It may well be asked why should the taxpayer pay so that some can have free power (usually the more well off)?
The only economic principle could be to encourage even more RE onto the grid to be purchased at, or below, current fossil fuelled generation costs. That would have the effect of reducing costs to those without self-generation capacity. It is however a very long term and expensive (in economic terms) project.
Does Australia have the political will and the economic resources to embark on such a project? Does it have to be done all at once? Should it only apply to new subdivisions? What happens to those in older suburbs? Who bears the cost? Can we afford to ignore it?
In transformer construction if you are going to increase the diameter of the copper wire you might increase also the area of the iron core or you have to decrease the input or output voltage.
Good thought. My idea is to decrease the output voltage requirement. I am not sure if that includes dropping the resistance of the transformers but every little helps. Again it comes back to cost/benefit.
Capacity is one element of cost with anything, but quality and operational margins must also be considered, hence the term 'cheap AND nasty'. In the end you get what you pay for. The concept of a motor vehicle is a reasonable example.
They may all carry out the same function but in the end what is the comparative term of life unit cost? Two transformers may have the same power rating, but one is considerably superior to the other in quality and performance.
It might be trite to suggest that a state-owned utility would probably purchase the one with the lowest price (lowest tenderer). Profit driven state (taxpayer) owned services is probably the wrong economic model - but that is what prevails in Australia at this time.
'Never mind the quality - feel the price.'
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