On Mon, 18 Mar 2019 at 12:05, James Cameron wrote: > I think by focusing on insolation, Russell has misunderstood my point. > Not really, but I did add some more consumer relevant points as well. Panel angle and snow and annual insolation and a bit more are still relevant commercially. I doubt that we disagree greatly if at all. What matters most for a given location is the spot price into the > network, the cost of extending the network, and how the price varies > across the insolation curve. > > Here's a farm with the panels all facing west instead of solar > optimum. > > https://goo.gl/maps/CZ71fMiRjrs > > Yes. I'm aware of the practice of skewing panel alignment to maximise something other than peak energy. (In a domestic context: In my nephew's 10 kW array he has panels set to Winter maximum to maximise winter energy without panel angle changes. And but > Here's their spot price per megawatt by scheduled demand > > > https://aemo.com.au/Electricity/National-Electricity-Market-NEM/Data-dash= board > > 30 min spot price currently 102.73/MWh - was about $98 when I first looke= d some hours ago. That's $0.10273/kWh - which may be OK for wholesale rates but would not make a residential customer aiming to achieve system payback very happy. Odds are that on some evenings they get MUCH more than that. For a residential owner my prior suggested criteria of " ... generous feed-in arrangements (or full grid replacement output) ..." still seem OK. Feed in rates are often very low compared to cost of units residentially. Whereas if you can use panel-power when you would otherwise be using grid power then every unit 'pays you' at grid rates. At residential rates per unit a cost effective system may break even in an acceptable time frame. I'd be interested in knowing what the payback period mis for your system. For commercial suppliers, if $0.18/kWh was the best they got I'd be surprised if it was a good investment. I may be wrong. Russell > So this farm is facing for the evening peak, and can bid into the > market based on generation forecasting and cloud observations. With > error bars on the forecast, they can potentially limit generation to > avoid hitting over-generation penalties. > > https://solcast.com.au/ is a forecasting service I'm familiar with, > and I've been experimenting with the data. > > > https://solcast.com.au/utility-scale/short-term-solar-forecasting-core-bu= siness-or-distraction/ > has an interesting explanation. > > It's about the same level of optimisation and engineering that is > applied to grid scale thermal generation, but the fuel price is much > lower. > > -- > James Cameron > http://quozl.netrek.org/ > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .