Month: September 2021

I’ve recently been on a mission to rearrange my home cooking and energy utilisation around days of concentrated sunlight, so as to maximise the utilisation of free and available energy from our solar panels and minimise our energy expense. To date, every time that this has happened has been on a Saturday.

This is massively lucky. Saturday is my one real day off. I’ve been planning my menu ahead but it is frustrating when you look ahead and all your available cooking days have cloudy or rainy weather. On this occasion, we had a disappointing forecast of rain for the whole week, but it somehow managed to reverse, giving an impromptu day of sunshine.

Basically what this means is that I batch all my cooking into one sunny day, and simply have some form of energy consuming appliance running from morning until sundown. I bag leftovers from meals and freeze them for microwaving later, for use during cloudy periods where there’s not much free energy going.

I did the sums and realised that this process would save me between $500-$600 per annum, removing from the grid a drain of around 2200 kWh of power annually. That’s about a whole month of winter power.

It also has the effect of improving the return on investment of my 1.5 kW solar power system, without the need for battery storage. I’ve been fairly disappointed with the actual performance of my panels, which have once all the real world adjustments have been made, resulted in an annual ROI of between 4 and 5% (not amazing on a system that gradually degrades over time and may only have a 30 year lifespan). This change of use has the effect of pushing ROI up as high as 15%. Now all of a sudden solar panels can be worthwhile.

Not to mention the effect of retail energy price inflation. My sums have this at 3.11% annually, but during periods of peak inflation such as currently, it could be much higher.

The carbon emissions saving is much of a muchness, but given our reported current reliance on coal burning, it could be considerable.

Basically just really excited at my little innovation and wanted to share my nerd little achievement with the world.

I’ve recently been thinking about solar panels in a different way. Instead of dealing with capital cost and return on investment, which has chiefly been the focus of many of the other blog articles that I have written on this site, I’ve been instead thinking about managing solar panels from the standpoint of considering the diurnalilty of the sun and how we can tailor our food production approach to what’s abundant and currently available. This has led my thinking down a number of different roads, such as a general revised approach to seasonal cooking with regards to solar panels, and even looking at weather forecast applications to tailor my cooking regime and menu to the available daylight hours that can be found on a coming day.

Any New Zealand solar panel user has dealt with the frustration of seeing even small 1.5 kW solar panel systems such as ours massively overproduce in summer and massively underproduce in winter, relative to the household’s requirements. That’s the reality of living at a far point in the southern hemisphere. And many in the same position will have asked the same question – now that I’ve got them, how do I get the most out of them?

An example – the winter soup

Soups are most often associated with winter – nothing seems as warming as the thought of a freshly made winter soup in a warm oven during the colder months. Yet from an electricity consumption standpoint, if your oven is powered by electricity, then it is most likely that cooking things low and slow at a high heat intensity will result in your household overdrawing from the grid, resulting in higher winter costs and carbon emissions from dirty imported coal.

Far, far easier is it to have the soups pre-made, and simply resting in your freezer, to be reheated in the microwave when needed and in so doing to minimize the impact on your household when your solar panels are least able to support your consumption. From experience I can tell you that the flavour, if not the feel, of a reheated soup is no worse than when freshly prepared.

Solar panels are about facilities management. And there’s perhaps no greater conceptual leap in the facilities management of solar power than factoring in the integration of weather forecasts into home cooking plans. Each week I sit down at the local café and write my menu for the week. The step I have failed to consider, and which would be easy to implement, is to also look at the weather forecast for the next 7 days.

Anybody with a smartphone device is able to get relatively accurate weather forecasts through Google. At a glimpse, even in winter, one can see the relative levels of sunlight availability across each of the seven days to come (and even click into that day if you want more granular information).

By far, the least energy intensive process for heating food is microwave cooking for two or three minutes on a pre-made meal. Therefore, it stands to reason that on overcast or rainy days, we should rely on the microwave more heavily.

The most intensive is the stovetop and the electric oven. Therefore, it makes sense to have the oven running when the sun (and hence solar power generation capacity) is at its peak.

This leads on to other questions, such as:

–          How can space in the oven be maximized so as to produce multiple meals at once?

–          How can we manage the maximum storage life of freezers so as to ensure efficient recycling and minimum wastage of resources?

–          What do we have to mindful of in this process that may result in health risks?

The simple overall goal of this exercise is to minimize the kWh consumed on a basic task such as food preparation, ideally so that it can fit within the band of solar overproduction during peak periods. But I can see how following this process may lead to considerable time savings as well.

What this approach may point to is a more total shift in the thinking of how we move energy consumption from one time period (or even one season) to another. What do we need that produces energy? Then – how can we time our usage of energy to give us what we need in a way that’s least expensive and produces the least environmental impact?