Solar PV guidelines and checklists

About a year ago I posted about a “five minute guide” I wrote while still at Arup in Cape Town.  This aims to flag some of the key technical things to consider if you, as a building owner or manager, are considering installing solar PV on your roof.

I came across another resource today; a checklist produced by the Interstate Renewable Energy Council, in the US.  This list aims to provide consumers in America with a series of questions or items to check when going ahead with a solar installation.  The aim is to have informed customers, asking the right questions and entering into a contract with a good basis of understanding.  This will hopefully result in service providers being held to an acceptable standard, and a reduction in the number of complaints being made against industry parties.

It’s quite a long list, and may be quite complicated for a layman.  It also suggests asking the installer for various bits of documentation; and it’s quite possible that the average homeowner may receive such documentation and not know if it’s adequate.   But it may be quite a good resource for larger consumers to implement, particularly where both PPA and leasing options are available.  You can find the checklist here.


Australia’s solar PV rooftop installations

Australia is great for rooftop solar PV installations.  Pretty much everywhere you go, particularly in Queensland, you see PV on roofs.

Solar PV3
Accommodation resort in Townsville, with a pretty impressive installation

In 2014, household and rooftop solar installations under 100kW generated nearly 5,000GWh, accounting for over 2% of total generation or 15% of renewables generation.  There’s over 4GW of small scale solar systems installed as at the end of 2014. In addition, there are over 900,000 solar water heating systems installed too. [CEC, 2014]

I spoke to someone who recently installed the system below in Biloela.  They joined in on the solar craze quite late and are being paid 6.53c/kWh exported to the grid.  They organised a deal with the installer to reduce overall installation costs but expect to have the system paid off in four years (even with the reduced subsidy).  They’re also saving from the get go as they’re paying it off in instalments, so their overall electricity bills have gone down  from the start.  They’re also trying to move some of their electricity usage into the day (dish washers/washing machines), when they can offset their electricity consumption rate, and this is helping them to save even more.

Their parents accessed the subsidy when it was still around 26c/kWh, and they are laughing their way to the bank it seems.

3kW system installed in Biloela, Queensland
3kW system installed in Biloela, Queensland

In Boonah (I went to all the big towns) I visited a retirement village where there were a number of solar systems installed on the independent living units.  These had been installed on a leasing arrangement, and the systems are still owned and maintained by the original installer.  The residents had been asked if they would prefer to purchase the systems, as they’d make more money over the longterm, but this would require these elderly home owners to maintain the systems.  Considering that many of these were installed when the rebate was still 50c/kWh, it’s unsurprising that most have elected to opt to retain the lease.  The lady I spoke to was making about $100 a quarter which she saves up with the utility, and claims back when it gets to about $400.  This was a story that made me really see the possibly unreported benefits that this rebate has had.

Solar PV1
Boonah retirement village installation

Cape Town residential electricity tariff; how is it impacted by the installation of a solar PV system

A question came up from a solar PV installer in a forum session that I attended the other day that demonstrated that even those in the industry don’t really understand some of the challenges facing the City of CT with regards to tariff structure.  The question was something along the lines of “Why has the City come up with an embedded generation tariff with a daily charge that can be more expensive than the residential tariff – thereby disincentivising people to install solar PV systems on their home?” I’m paraphrasing.

To start with the basics:

There are two main tariff types for Cape Town households – Domestic and Lifeline. The intention of the Lifeline tariff is to provide low income households or, as it is currently set up, ‘low consumption’ households with free basic electricity (between 25kWh and 60kWh).  Some mid- or high-income households currently qualify, because they have a low monthly average consumption, but the City is planning to address this by including a maximum cap on the value of your property that qualifies (R300,000).

Let’s assume then that if you’re thinking about installing a PV system, you’re on Domestic, and not on lifeline.  If you can afford a PV system you’re probably not the target market for the free electricity programme anyway.

The VAT inclusive domestic tariff is currently set up like this, and will be increasing as of the 1st July.

  • 0-600kWh – 153.63c/kWh
  • > 600kWh – 186.81c/kWh

This is called an inclining block tariff (IBT) and there used to be a lot more blocks to it, instead of just two.  The more you use, the more expensive each kWh of electricity becomes.

There’s a lot written about IBT’s, and they’re designed to protect low-income households from increasing electricity tariffs.  They effectively represent a cross subsidy of electricity by the middle- and high-income households.

It’s not my intention to discuss the merits and demerits of this tariff structure in this post.

In response to increasing pressure for the City to allow installations of small scale embedded generators (which for the purpose of this post we’ll assume are all solar PV installations), the City developed the Residential Small Scale Embedded Generation tariff.

This tariff, for the first time, introduces a fixed daily fee which is payable, regardless of how much electricity you consume.  It is set up like this (VAT inclusive):

  • Service charge – R13.03/day
  • Energy charge – consumption – 109.17c/kWh
  • Energy charge – generation – 56.68c/kWh

What this means is that, for a 30 day month, you’d pay R390.90 in service fees, regardless of how much electricity you consumed or generated from your system.  However, you’ll notice that your marginal consumption tariff is around 2/3 of what you’d pay if you were a normal residential customer (block 1).  They have split out the fixed costs from the variable costs.

The City also does not allow you to sell them more than you buy, so you can never be a net exporter.  This will likely change in the future, but right now it’s in response to NERSA requiring you to have a generation licence if you sell power to another person, and this is the City’s way of getting around this.

Why has the City set it up like this?

Having the grid available to export electricity into, and effectively using as a battery, costs someone money.  There are maintenance or upgrading costs that need to be accounted for. This daily service charge is the City’s attempt to recoup these costs regardless of how much electricity you use.  This helps to separate the cost of the two services the City is providing; namely the provision of an electrical network, and the delivery of electricity in kWh’s.

If there was no service charge, who would pay for the grid? Ultimately, it would be people who did not have any embedded generation.  And who would that be?  Those who couldn’t afford it.  Which would effectively be a cross subsidy in the wrong direction.

And before you say ‘but it’s green energy, so should have a premium payable,’ that argument is nice for Germany, where people can afford to choose whether they’d like to have an installation on their roof.  It doesn’t work here.  And the recent trends in PV prices mean it doesn’t need to work here for PV to take off.

Commercial tariffs already have a daily service charge, so are already set up to slip nicely into an embedded generation tariff structure.  There is talk of moving the residential tariff away from an IBT structure.  If this happens this issue will become a non-issue and this blog post will become irrelevant.

Also, for the record, 186.81c/kWh is a big tariff to be paying.  If you’re consuming over 600kWh and have moved onto this tariff, you’ll be paying big money each month for electricity.


I’ve included the VAT amounts as this is what the average household will be paying.  If I was looking at the commercial set up, I’d probably be using VAT exclusive amounts.

You can read up the impacts that IBTs have had here:

The City’s current electricity tariffs can be found here:

The difference between solar thermal and solar PV

I was in a meeting this week and found myself talking to someone who confusing solar water heaters with solar photovoltaic panels.  This took me a bit by surprise as I thought people were quite familiar with the two different technologies, as they’ve been around for a while, but it seems not.

Solar Thermal

Solar water heaters or solar geysers use the heat from the sun to warm up water, most often in flat panels on the roof, or water contained in tubes surrounded by a vacuum within another tube.  The warmed water is stored in a geyser, which often has back up heater like a normal geyser, to ensure there is hot water even on overcast days.  Flat panels are often used in temperate climates, where there is a lot of direct sunlight and where it is not typical to have overnight sudden frost.  Evacuated tubes are good for colder climates, or where there is sudden frost overnight, as sudden freezing of water causes it to expand and can crack flat plates, whereas the vacuum around the inner tube provides a measure of insulation from frost.

Solar water heaters help to reduce the electricity consumed for heating water, and can be an excellent investment for households, where a large chunk of electricity is used on heating water.

Solar photovoltaic (PV)

Solar PV systems are able to convert sunlight to electricity.  They are typically made up of individual silicon based cells that are connected together in a module or panel.  They can be connected to a building’s distribution boards to supplement the electricity supplied by the grid, or the electricity can be exported directly from the system to the grid.  They are able to convert direct sunlight, or, depending on the type of module used, they can generate electricity even on a muggy day.  Unlike solar geysers, they perform better when the module temperature is kept fairly low, and the light energy that is most important; not the thermal energy.

Both systems can be installed together, as they serve very different purposes.  It doesn’t make sense to install a PV system on its own if your biggest electrical load is from your geyser, and if you don’t have any hot water needs, it clearly doesn’t make sense to install a solar water heater.

Other solar thermal applications

Solar thermal installations can also be used to generate electricity, but this makes use of the thermal energy to heat water to turn a turbine, to generate electricity.  Thermal -> mechanical -> electrical energy.  These are often large scale installations, called Concentrated Solar Power (CSP) but there are some small scale systems that have been installed.

Lastly, solar thermal can also be used to run a building’s cooling system, as strange as that sounds.  The water is heated up, the steam is used to power the chilling machinery, which runs the airconditioning system.  Thermal -> mechanical -> cooling.

Generally though, most solar thermal installations are your run of the mill solar water heaters.  How to tell which you have:

  • do they have a series of glass tubes? – solar water heater
  • if it’s a glass plate, do they have lots of individual squares that are distinguishable? – solar PV
  • if it’s a glass plate, which looks like a solid black panel and/or there’s a tank installed above it? – solar water heater

EDIT: I have been reminded that I forgot to write about absorption chillers.  Read up on them here:

A summary from the DoE can be found in the presentation linked.

Some key items for me with regards to Bid Window 3:

– 93 bids have been received, amounting to 6,023MW whilst the available
MW for allocation was 1,473MW.
– 17 preferred bidders have been announced and there are 6 PV projects,
7 wind, 2 CSP, 1 landfill gas & 1 biomass
– The Northern Cape has the lion’s share of the jobs again, with 82% of
all the construction jobs. Gauteng has got six jobs in there out of over
7000… This seems to be largely driven by the CSP facilities, both of
which will be in the northern cape. The PV plants are split between four
– 50.4% of equity across the projects is from foreign investors as is
25% of the debt
– PV, wind and CSP had a dip in Round 2 in operational jobs/MW, but they
have all increased in Round 3 (wind & PV most notably… where there is the
most competition) Not sure if this is a response to socio-econ drivers.
– The bidding tariffs for each facility has been provided. Not sure
this was available before, but it is quite interesting that this is
available now. The rumoured cheapest PV price is 86.41c/kWh from Adams
Solar PV2 (Enel?)
– Welcome to the party landfill gas & biomass.

Delay of REIPPPP Round 3 preferred bidder announcement but hints of outcomes out already

There are still some things to be gleaned from the notice on the IPP
website today…

– If your PV facility was not 75MW you’re not yet listed as a preferred
bidder, as they’ll be awarding 6 projects at the 75MW cap = 450MW
– Landfill gas and Biomass have joined the party
– It is likely that we’ll be seeing 200MW of CSP with storage coming
online soon as the tariffs were only really favourable for CSP with storage
– Wind and Solar PV may have additional capacity made available, and
this should be announced before the 20th November.

The info below is found here .

The Department received 93 Bid Responses on the Third Bid Submission Date.

The Department has today, 29 October 2013, sent letters of appointment as
Preferred Bidders to 17 Bidders who submitted Bid Responses on the Third
Bid Submission Date. The number of appointments, and the total MW of
Contracted Capacity awarded to date, is as follows:

Onshore Wind – 7 Preferred Bidders totalling 787MW
Solar Photovolatic – 6 Preferred Bidders totalling 450MW
Biomass – 1 Preferred Bidder of 16,5MW
Landfill Gas – 1 Preferred Bidder of 18MW
Concentrated Solar – 2 Preferred Bidders totalling 200MW

The Honourable Minister of Energy and the Director-General of the
Department of Energy are currently not available to address the media and
interested parties about the outcome to date of the procurement in respect
of the Third Bid Submission Phase, and appropriate arrangements will be
made in due course for a detailed announcement regarding the Preferred
Bidders and the benefits to South Africa in respect of their projects.

The Department has today also sent letters of non-appointment as Preferred
Bidders to 18 Bidders. Those letters were sent to Bidders whose Bid
Responses were Non-Compliant with the requirements of Part B (Qualification
Criteria) of the RFP.

The Department has taken note of the fact that a large number of very
competitive Bid Responses were submitted for the Third Bid Submission Date
in the Onshore Wind and Solar Photovoltaic Technologies, and the Department
is considering the appointment of additional Preferred Bidders for those
Technologies from the remaining Compliant Bidders. As such, the Preferred
Bidders that have been appointed in those Technologies may not be the only
Preferred Bidders that are appointed in those Technologies for the Third
Bid Submission Date, and no final decision on this has been taken at this
time. The Department will make a further announcement regarding its
decision in this regard in due course, and is intending to do so by not
later than 20 November 2013.”

Delay of REIPPPP Round 3 preferred bidder announcement but hints of outcomes out already