February 16, 2017

Food

Feeling Hot Hot Hot: Solar Cooking in Action

Cooking can be challenging in itself. Following recipes, getting the right ingredients and hoping it comes out tasting delicious – unless you’re a top class chef, everyone has had a fair few burnt dinners in their time. When you’re off-grid however it’s not just worrying about what it tastes like, but how to cook the food in the first place!

Harvesting the power of the sun for cooking has been a practice conducted for many years.

Solar cookers have been on the market since the mid-80s and have become a popular option for safe and easy cooking with no fires or fuel involved. There are obvious benefits to solar cooking, after the initial investment it is a free renewable source of energy. Not only this, but it is seen as a healthier way of cooking without smoke from fires etc.

Solar cookers convert the sun’s rays to infra-red radiation producing heat. Therefore, it is not the sun’s heat itself or the ambient air temperature outside the cooker that causes the food to cook.

There are three main types of solar cooker which can vary in their design and build.

The solar box cooker is derived from a box with reflectors that funnel the sun’s rays into the chamber which contains the food to be cooked. These models can reach very high temperatures, on average between 200-350°F, which is ideal for most baking needs. With a good heat retention and little need for supervision it is perfectly safe to leave food for long periods without fear of burning. Being a box shape these cookers are less likely to tip over and when constructed will have high levels of insulation.

The solar panel cooker on the other hand doesn’t reach temperatures quite as high; between 200-250°F. Essentially the design is a pot or pan within a plastic enclosure, with a 3-5 side reflective panel surrounding it to channel the sun’s rays. This type of design is best for slower longer cooking periods, leaving food very succulent. With no adjustments needed to track the sun, little supervision is needed.

Finally, the solar parabolic cooker can maintain the highest temperatures of the three main types and so can be used for grilling or even frying food. It can cook food much quicker, however usually smaller amounts than what can be held in the box or panel solar cookers. Also more attention is needed when cooking using this model, as the angle and direction of the cooker will need to be changed more frequently to track the sun.

There are many plans and designs for you to try if you want to have a go at a DIY solar cooker. Many designs include using materials commonly found around the home or are easily obtainable. For example, cardboard boxes, aluminium foil, black paint, some form of adhesive and even umbrellas!

If you don’t want the hassle
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Community

Changing regulations could cause off-grid “avalanche”

Solar panel suppliers in South Africa are predicting an “avalanche” going semi-off-grid or off-grid in response to new regulations that increase the costs of operating solar panels while attached to the grid.

According to the new regulations, 78-year-old Andrew Louwrens has an illegal solar electricity installation in his garden – despite having used solar panels since 2012.

Andrew, a retired SA Rugby administrator, received a letter from the City of Cape Town late last year ordering him to replace his illegal small-sale generation system – at his own expense – because it did not comply with regulations introduced after it was installed. Things got worse when, on Christmas eve, the council threatened to cut off his electricity if he didn’t comply.

“I installed the system in good faith in 2012. I was doing my bit for society,” Andrew said. “I also didn’t want big electricity bills when I retired, [and I have been] happily exporting excess electricity into the grid.”

Michel Malengret, an associate professor at the University of Cape Town, which owns the company that installed Andrew’s system, said the inverter he installed for Andrew had been approved globally, and at the time of installation there had been no local regulations.

“Using solar energy was very expensive then and government’s impression was that it would never happen,” Michel said.

Power utility Eskom said it viewed “the embedded generation connections, made without the required approval and permission, as illegal” and would not consider “retrospective applications”.

Cape Town’s mayoral committee member for energy, Xanthea Limberg, said residents had to ensure installations complied with standards and to replace non-compliant inverters with acceptable ones. But Michel argued that customers’ hands were tied by the expense of such replacements.

“Council only adopted regulations two years ago, so now those like Andrew who installed solar beforehand must fork out another R7000 for a new inverter. They must then pay a fixed charge of R13 a day for the ‘privilege’ of exporting excess energy into the grid,” he said.

Andrew and Michel suggest people in the same situation go partially on and off the grid, and stock up on batteries to store electricity.

Michel said that although Eskom had made it “virtually impossible” for “solar guys to work with the grid” he predicted there would be “an avalanche” of people going off the grid as the price of batteries came down.

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