The Cashmere Connections top making energy savings and generation project has been undertaken and completed. Cashmere Connections’ top making is now a net energy exporter.
This project has reduced our carbon footprint and generated savings, enabling Cashmere Connections to hold our top making prices, even though energy costs are rising.
Without conducting a network study (which is costly) the power utility allows a maximum inverter export limit of 15KW, and a maximum inverter size of 30KW. The difference (15KW) is energy that can be used by the business if the load is available. Local energy use takes precedence over exporting energy. If there is no load the energy is exported to a limit of 15KW. If we are powering our site and hit our export limit, the energy is spilled by limiting the solar energy converted by the inverter.
Clean energy certificates are issued for solar installations up to 133% of the inverter size (30*133% = 39.9 KW). In the unusual situation where the solar energy available is greater than 30 KW, it is not converted by the converter.
For solar energy to be above 30 Kw, the day must be sunny, reasonably cool, and the sun at 90 degrees to the solar panels.
Charles (the Electrical Engineer) developed a spreadsheet that calculated the solar output based on the position of the sun, the size of the solar panels and the angle of the panel installation. This was compared to our 2022 energy consumption.
He concluded:
1) Reducing our energy imports would more than pay for the solar installation loan repayments.
2) There are good theoretical reasons why the clean energy council limits the array size to 133% of the inverter size. The period where the inverter covers the sites energy use gets longer (bad solar days), and the period where energy conversion is limited by the inverter increases (good solar days). The saving-loss cross-over is at about 133%.
3) There was, in our case, little advantage gained by adding the expense of mounting the panels at an optimum angle.
4) If you install a battery, your energy use can be at different times from when the energy is created. After the analysis of our energy use and the modeled energy creation, we concluded that the advantage of battery storage would be small with a payback period greater than 20 years. As battery technology is developing at a rapid pace, we will review this decision in a couple of years’ time.
5) There would be periods where energy would be spilled because we could not export or use it. What we needed was a load that could be added when excess solar capacity was available.
Our car was old, with a travelled distance of over 375,000 Km. Moving to an electric powered vehicle and a smart charger that only charged when solar power was being exported would give us a way of using the excess solar energy and greatly reduce our motoring costs.
The smart charger we have installed at the factory.
Our first choice was a Tesla Model three extended range. It offered one of the longer ranges and it was efficient (13.1 Kwh/100Km). This got canned when we discovered that our insurer would not insure a Tesla. There were other companies in wouldn’t insure one either. A broker found car insurance for us, but the premium was over $ 4000 a year.
Our second choice was a GWM Ora extended range, not quite as efficient (14.0 kWh/100 km) and offered not quite as long a range. To overcome our range anxiety the dealer allowed us to use it for a weekend. We took the vehicle on a couple of our regular longer trips. The longest and most telling because of the steep and long climb in windy conditions required 80% of the range, giving us some room for battery degradation.
The purchase of the GWM Ora has further reduced our carbon footprint as we are no longer buying fuel.
Test driving the GWM Ora "Funky Cat".
During all these changes our air compressor failed, giving us another opportunity to increase our efficiency. Our reciprocating compressor has been replaced with a screw compressor with a control system that matches screw speed with air consumption. The screw compressor is quieter, more energy efficient and hopefully longer lasting.
Our new screw compressor.
As noted in the introduction, the solar installation and the increased efficiency has resulted in a business that at present is a nett energy exporter.