Roots 'n' Shoots: Solar Power in South Africa Part 3: Solar & Seasonality, Living with Solar in Gauteng, South Africa

Why is RnS Moving to

Google had brought out an algorithm update in May 2017. With previous updates like Panda or Penguin, Mr G had penalized blogs or websites with low quality content and those more focused on aggressive adverts (including multiple ads or pop-up ads in articles). However, many blogs/websites that weren't shady got penalized beyond recovery too and a lot of people lost their income. The May 2017 update has had wide-scale effect on blogs and websites, but without any explanation from Mr G as to why or what it does. RnS has been hit by it too and hard. RnS organic search stats (i.e. users from Google) have dropped by 75% since. Even though RnS is not a source of income, I tried to figure out why RnS is being culled. It seems that it doesn't really have anything to do with RnS per se, but likely because RnS is FREE and not paying for page ranking (via AdWords or Ad Ranking). Now it is likely being aggressively shoved to lower page rankings to accommodate the paid ads.

I cannot rely on Mr G anymore to get RnS' content where it is needed. So I am busy moving RnS to Wordpress where you can find me as Whisker Flowers @

I am also imposing 301 redirects from already moved posts and pages!

- The Shroom - (AKA Whisker Flowers)

Saturday, 5 September 2015

Solar Power in South Africa Part 3: Solar & Seasonality, Living with Solar in Gauteng, South Africa

How’s your Solar in Winter? (Author: The Economist)

Winter sneaked up on our solar electricity system during July. We hardly took notice of the change in the length of a day before installing solar and now it matters. We lose up to 6 hours in daylight from the longest day in summer to the shortest day in winter. That is a lot. The days shrink by almost 2 minutes per day, that’s about 20 minutes every 10 days! The result is that the supply of solar electricity shrinks as the days get shorter and the demand for reservoir electricity increases as the nights get longer.

The daylight and night time effects combine with a third negative, a drop in temperatures for a triple punch to the solar electricity system. The drop in temperature means that all heat based electricity needs increase and here I exclude home heating. The heat pump takes 3 hours to get the geyser temperature to 60 degrees when in summer it would take between 1.5 and 2 hours to do the same job. The kettle takes a few minutes more every time it is used. The dishwasher has to contend with much lower temperature water inflows to be heated up and the tumble dryer also has to work harder to dry the clothes. It all adds up to increased electricity demand when days get shorter and reservoir needs increase.

Winter is when you find out how robust (or not) your solar electricity system is. So, let’s look at supply of electricity from the solar panels.

There is one additional observation with regards to supply in winter which matters for us here in Gauteng South Africa. Winter sees atmospheric interference which causes hazy mornings and afternoons. So the solar electricity production is muted even with good sunshine at around 08h30. Once the hazy conditions clear up around 09h30 we experience a steep rise in electricity production. Sadly the loss of electricity generation due to haziness has a significant effect on total daily electricity production in winter and haziness is the norm not the exception, so we show hazy conditions on the graph as the “best” case. The electricity generation in winter is about 55% of summer generation with hazy conditions, but on clear winter days we can get around 65%-70% of summer electricity production.

Overcast days in winter are terrible for solar electricity production but fortunately Gauteng is a summer rainfall area with very few overcast winter days. We’ve discussed generator back-up in our first article here, Part 1: How to go off grid permanently (The System Set-up).

The change is season requires a resource management response from us. We have to use the electricity with more care with the most important effect having to spread the use of electricity. An example is not to do the washing only once a week, which requires the tumble dryer to run 4 times during the day but to spread the washing over two non-consecutive days. Thus, the tumble dryer runs only twice on those days. Demand management will be the subject of our next post.

Here is a table of our summer and winter electricity supply and demand data. Keep in mind that it applies to our system and our household needs, which for each household would differ.

Our solar electricity system can supply up to 56.5kWh electricity per day in high summer. We usually only need around 20kWh per day in summer on high use days, which means that we have surplus supply of more than double our needs. Here the “use it or lose it” principle applies so one can store it in ever larger battery banks or use it for unusual needs such as cooling the house (aircon) or processing of excess fruit and vegetables into jams or for drying (which uses the oven), etc.

In winter the picture changes fairly dramatically. We produce only around 31kWh electricity per day while a high use winter day can easily get to 28kWh. Our winter surplus now falls to only about 3kWh per day slightly more than a 10% surplus margin. Our daylight supply in deep winter is tight and our overnight reservoir is also under pressure. I’ve discussed the battery banks here, Part 2: Living with Solar in Gauteng, South Africa. Our solar electricity supply is adequate albeit tight as the few high winter weeks are manageable and soon after we are back to ever increasing surpluses as the length of days increase by 20 minutes every 10 days.

Sun position in the sky at 18h00 from January to December 2015
(read from- top left to bottom right). 
Notice differece in available light;
this has an effect on solar production throughout the year.
Picture generated with screenprints from Stellarium 0.11.2 software.

The solar experience so far is a positive adventure with no load shedding and with significant economic benefits!

Program reference: Stellarium - A free planetarium software, allows you to look up and track stars, planets and constellations in the night sky.

Our solar system was designed and installed with the assistance of Jurie Venter, cellphone 083 557 6031 and email . For details on the whole system, see the post How to go off grid permanently.

Related Posts:

Part 1: Solar Power in South Africa - How to go off grid permanently (The System Set-up)
Part 2: Living with Solar in Gauteng, South Africa (Batteries)

Please share with fellow gardening enthusiasts via the various sharing buttons at the end of posts/pages! Else you can vote for posts through the Google reactions bar at the end of articles. To stay up to date I have provided several reader and social networking platforms with which to subscribe: TwitterPinterestRSS Feed Reader or Email/Follow directly using the Blog Followers widget on the left hand side toolbar. Thank you for reading and please feel free to ask if questions arise - I appreciate comments and ideas too! 😆

Absolutely Gorgeous Beautique

Absolutely Gorgeous Beautique
Your beauty, weight loss, slimming and skin care salon of choice! Products with International Shipping!