Posted in: Frequently Asked Questions

The definitive guide to solar PPAs

There’s been growing interest in solar PPAs over the past few years, and they are now much more mainstream. However, you may still have some questions about PPAs and solar finance. What are PPAs, and how can they benefit your business? We’ve put together a definitive guide to help. 

What is a solar PPA?

The term “PPA” is swung around quite a lot in the solar industry. PPA stands for “Power Purchase Agreement”, and it signifies a type of contract between an electricity generator (or Independent Power Producer – IPP) and an electricity consumer (or offtaker) – such as a commercial operation. A solar PPA is therefore a contract between a solar generator and an offtaker, stating that the generator will provide solar power and the offtaker will buy the solar power from them.

As a form of electricity, Solar PV is an easily-deployable, very safe option without any moving parts that produces electricity during light hours of the day, and therefore it often makes sense to embed the solar PV system directly into the factory, retail centre, warehouse, etc. where it will be consumed. As such, many commercial and industrial solar PPAs include the construction of an embedded generation solar facility on the site where the power will be used. In this instance, a solar PPA is a way for the customer to procure clean electricity and save on their electricity bills without deploying any CapEx, and only paying for the electricity that the system generates.

However, PPAs can also be entered into for clients where there is either too little space or too much energy demand to generate solar electricity directly on the site. In these situations, solar wheeling agreements can be entered into, which allow the purchase of solar power from a remote solar facility, such as a large solar farm, to be “wheeled” through the electricity grid and to the customer. Wheeling typically suits energy-intensive operations such as mines, smelters, data centres, and other large commercial operations.

Typically, the larger the size of the PV system, the lower the tariff. This is why solar PPAs are best suited to energy-intensive operations, where there is little chance of exporting excess energy. The most suitable size of the PV system depends on the client and type of operation, and is typically determined during a detailed feasibility process between the generator and offtaker. 

What are the benefits of a solar PPA?

There are several benefits of entering into a solar PPA, but they can be summarised into four main points:

  1. Cost saving

The major reason for entering into a solar PPA is the significant cost saving that customers tend to encounter. While grid tariffs have been increasing, the cost of solar PV components has reduced dramatically over the past 10 years, meaning that the cost per kWh of solar electricity tends to be much cheaper than power from the grid and other forms of onsite generation (diesel genset etc.). In addition, the solar PPA tariff includes all expenses relating to the solar system: upfront installation costs, part replacement, comprehensive asset insurance and ongoing operations and maintenance, meaning that the client will not have any hidden or unexpected costs over the life of the PPA.

  1. Carbon emissions reduction

Solar PV systems generate energy by converting the sun’s rays directly into electricity, forming a low-carbon, renewable energy source. A solar PPA is an easily accessible way for businesses to decrease their carbon footprint and meet their sustainability targets. 

  1. No outlay of CapEx or ongoing maintenance costs

If a customer wishes to procure their embedded solar PV facility outright, they will need to pay a supplier for the engineering, procurement and construction (EPC) of the project, which will have a large capital outlay. This is not always the best option for a business whose core operations are completely different to electricity generation, as the ongoing maintenance and performance of the plant will be their responsibility to manage. Whilst most EPC companies provide additional Operations and Maintenance services, it will be the responsibility of the client to ensure that those contracts are fully up to date and to log any issues with the service provider. 

  1. Future electricity cost perspective

Typically PPAs will have fixed tariff increases baked into the contract, ensuring that the future costs of electricity will be predictable and manageable. Historically, Eskom tariffs have risen an average of over 11% annually over the last 20 years, with a 15% increase announced in 2021. A solar PPA will have an escalation that is fixed and typically well below Eskom’s average and can be set in consultation with the client. 

How long is a solar PPA?

The main component of solar PV systems are the solar panels, with a market standard performance warranty of minimum 25 years. As such, typical PPAs range from 10 – 25 years. Although the length of the PPA is adaptable, the longer the PPA is, the lower the starting tariff will be. 

If your business is looking to procure sustainable power quickly, then the time of procurement should also be taken into consideration. For a simple solar PPA to take effect, there is typically a 5 – 6 month procurement time before the site establishment and construction, which incorporates the negotiation and signing of the commercial PPA as well as the design and licensing of the solar PV system. Here’s an example of the typical timeline of a solar PPA negotiation period:

Off-site PPAs that include a wheeling agreement may take longer to initiate because a solar generating site needs to be identified and permitted in addition to the normal PPA process. 

What’s the difference between a solar PPA and a solar lease?

Over the years, the terms “solar PPA”, “solar finance”, and “solar lease” have come to be used interchangeably, so what is the actual difference between these terms? The answer has to do with the history of energy legislation in South Africa and the allocation of risk.

Before November 2017, it was not possible in South Africa for Independent Power Producers to sell energy directly to consumers without a generation licence. As such, solar leases were utilised as a way for a private energy consumer to make use of a solar PV system by leasing the system instead of paying per unit of electricity the system generates. Then, in November 2017, an amendment to Schedule 2 of the Electricity Regulation Act allowed for private energy sale without the need for generation licence of projects less than a 1MW in size, which opened up the opportunity for Power Purchase Agreements to take effect. 

So the main difference between a solar lease and a solar PPA is contractual, and dependent on where the performance risk of the asset lies. In a solar lease, the performance risk lies with the customer or user of the solar PV system as they pay a fixed monthly fee for the system not linked to the output it generates. Whereas in a solar PPA the entire risk of the asset lies with the solar PV operator as only energy generated is paid for on a take-or-pay basis, making it a purely cost-saving mechanism for businesses.

Are there risks associated with a solar PPA?

As with any large commercial decision, the risks need to be understood up front. The main risks in entering into a PPA agreement include:

  1. The length of the contract

Whilst most business contracts are typically renewed on an annual basis, a PPA term is typically 10 years and longer to ensure the most cost effective solar tariff. As such, senior management will want to ensure that the cost and carbon savings associated with procuring clean electricity are worth the risk of entering into such a contract. This can be mitigated through various exit options including an option to purchase the system, which can be a condition of PPAs that allows the client to buy the solar PV system after a set amount of time for a periodic price that is agreed upfront, should the operational requirements of the business change.

  1. Changing operational requirements

The risk of changes to the business’ operational requirements is a standard business risk that should be considered for every new venture and/or product that is introduced, as it will have an impact on the overall efficacy of the plant or operation. If, for example, a product is no longer required and its manufacturing operation suddenly starts to use less electricity, this could impact on the cost-saving aspects of the PPA. Most PPAs are arranged on a “take-or-pay” basis, meaning that the client is responsible for paying for all the electricity that the system generates, including instances where the customer cannot take the energy not at the fault of the generator. In addition to careful business management, this risk is also mitigated through careful feasibility and design phases, which look in detail at the electricity requirements of the building or facility before suggesting the total size of the solar PV system to the client. Similarly, a PPA has a fixed tariff increase each year, meaning that electricity costs will be very predictable into the future, allowing for better business planning. 

Is a solar PPA right for my company?

Understanding if a solar PPA is the right option for your company is a decision that comes down to business management decisions around cost saving and sustainability. On cost saving, does your business have energy-intensive operation(s) around South Africa, and is a large amount of your company’s operational budget spent on electricity procurement? If so, a solar PPA is a great way to reduce electricity costs quickly, with low risk to the business, improving the profitability of your operations. Similarly, a PPA also ensures that future electricity costs are predictable, hedging against unpredictable Eskom increases.  

From a sustainability perspective, does your business have sustainability targets that require a reduction in carbon emissions or a requirement to procure renewable energy? If so, a solar PPA is a great capex-free way to reduce reliance on grid-supplied electricity, which in South Africa is highly carbon-intensive. For example, the CO2eq for South Africa’s grid is just under 1 kg per kWh, whilst solar is less than 0.01kg per kWh. From a procurement perspective, solar PV is considered 100% renewable, so the more solar PV that fuels your operation, the closer you will be to your renewable energy procurement target.

New report shows that job creation in the PV sector is inevitable

In the most conservative case, we’re looking at over 30 000 jobs created per year in the solar PV industry 

Job creation is one of the most important considerations for the South African economy. Sitting at around 29%, unemployment is a serious hindrance to the South African economy. The creation of solar PV systems for the government and private clients brings down costs and increases energy reliability, bolstering profitability and growing businesses. However, the question of how many jobs the PV industry creates has been a hot topic for several years. 

A new study, completed by the CSIR and commissioned by the South African Photovoltaic Industry Association (SAPVIA) with sponsorship from SOLA, has set out to look at just how many jobs solar PV has created in South Africa so far, and what we can expect from the industry in the future. 

Measuring jobs in the PV sector is tricky, because of the variability of jobs throughout the life-cycle of each plant. Typically, both large-scale and embedded generation plants will have quite a lot of employment during the construction phase, which taper off when the plant goes into Operation & Maintenance (O&M). However, these jobs last the lifetime of the plant, and thus are cumulative over time. 

How are solar jobs measured?


There’s been much discussion about how to measure jobs in the solar PV sector,  which has not had a unified approach or metric, resulting in confusion about the numbers of jobs created by the industry. As such, the first step in the research was coming up with a useful way to measure jobs, particularly those in the solar PV sector that tend to undulate based on construction times. 

Based on an international literature review and experiences in other survey approaches, the CSIR used “Full Time Equivalent” (FTE) as a metric to measure jobs. A FTE job looks at the amount of time that a worker spends at a job compared to a full time employee. For example, if an employee only works half-time, their FTE score would be 0.5. As a result, the metrics represented by FTE show what the equivalent full-time employment would be per annum for a particular job.

In addition, the CSIR used a standardised unit output of MW per annum in order to be able to compare jobs across the value chain. As such, the jobs in the analysis and in the future scenario modelling are represented FTE jobs per MW per annum. This allows the job statistics to be comparable across different sectors and in relation to other forms of employment creation, and takes a conservative view on estimating jobs.

The predicted scenarios for job creation in the solar PV industry in South Africa

The report looked at historical data in order to create a model to predict future employment scenarios in the sector. It modelled three different scenarios, the IRP 2019 scenario, the accelerated case scenario, and the high road scenario.

  1. The IRP 2019 scenario

This scenario looks purely at the jobs resulting from the Integrated Resources Plan 2019 by the South African Department of Mineral Resources and Energy. In this scenario, the solar PV industry would create between 33 000 – 35 000 jobs per year from 2022 and 2030, but there would be little consistency and large variations between years. 

  1. The accelerated scenario

This scenario takes into consideration the growth of the market outside of the IRP guidelines, and assumes that utility scale solar PV will be built in addition to embedded generation, owing to the government’s intention to allow more embedded generation to plug the energy supply gap in the short term. In this scenario, an initial spike in job creation of 51 580 FTE jobs will be created during 2022, followed by a dip back to 31 131 FTE jobs in 2023 and climbing to consistently to 37 975 jobs by 2030

  1. The high-road scenario

In this scenario, the predicted import of solar modules is expected to increase, in addition to the building of both Utility and embedded generation solar PV facilities, which continue to grow post-2022. In this scenario, jobs are expected to bounce up in 2022 to 53 422 FTE jobs, and return to 33 972 in 2023, growing steadily to 39 817 FTE jobs in 2030.

What does this mean for the sector?

The jobs report paints a picture of what the expected job creation trajectories will look like. The research highlights the fact that the halting of renewable energy procurement in 2015 was devastating to the jobs in the sector, but has not prevented it from recovering in the recent years. There are some important aspects to consider in order to ensure the maximum job creation:

  • O&M jobs are the most sustainable, as they run throughout the lifetime of each PV facility (usually around 20 – 25 years). They have the potential to create substantial, lasting job opportunities in the sector.
  • Localising PV component manufacturing could have a significant effect on the growth of PV-sector jobs in South Africa, particularly if there is a clear path to how much the sector will grow each year.
  • The embedded generation market is a very important player in the creation of PV jobs, but has been hindered by policy uncertainty. 

Overall, the report shows that whichever scenario ends up playing out, there is likely to be significant growth of solar PV jobs in the coming years. 

Download the full report here.

Interested in working for us? Have a look at our careers page for possible vacancies.

South Africa electricity grid supply

The great opportunity to reform South Africa’s power sector

Over the past few weeks, there has been encouraging movement in South Africa’s electricity sector that indicates a gradual opening of the electricity market. NERSA recently confirmed that licensing of electricity generation over 1 MW will be allowed without ministerial sign-off, which could make the processing of renewable energy generation licences more efficient; and municipalities were recently granted the freedom to procure their own power. In addition, the prospect of the renewable energy bid window 5 (REIPPP 5) opening in December indicates that South Africa is starting to take the procurement of renewable electricity seriously. 

And whilst renewables still make up a small share of South Africa’s total generation capacity, the growing cost gap between the grid and solar, along with falling battery prices, means that South African electricity consumers are faced with something new in the context of our traditionally monopolistic electricity market: choice.

As was discussed in our previous piece on going off grid, it is clear that many consumers are choosing to go entirely off grid. However, mass grid defection is not necessarily the most optimal system for the majority of South African consumers. If the government suppresses private and distributed electricity generation, forcing customers to choose between staying on grid with expensive, unreliable power, and quitting the grid entirely, there may be large-scale grid defection as businesses choose to forego the unreliable and expensive grid. This will erode both Eskom and municipal revenue streams, driving more tariff increases that impact many South Africans

However, effective grid modernisation will turn potential defectors into ‘prosumers’, who choose to remain grid-connected and participate in a more open and mutually-beneficial electricity market. There are already some municipalities in South Africa that allow for grid feed-in (see this convenient list), which helps grid-tied solar PV systems become more profitable. However, we’re still a long way from a mature electricity market, where the cheapest electricity can be generated and consumed when it is required, enabling overall cost reductions of electricity. 

A modern grid will make use of enhanced infrastructure for better management of variable renewable energy, and ensure equitable electricity pricing that allows consumers to generate their own electricity and/or buy electricity from independent power producers whilst paying fees to utilise the electrical grid. This could generate new revenue that would enable better maintenance of the existing infrastructure, further replacing outages. 

However, we are still a way off from this “modern grid” idea. Some of the immediate steps that could be taken to enable grid modernisation, preventing mass defection and price increases, could include:

  • Laws and standards must be updated to cater for all technologies in the energy mix. 
    • We’re starting to see some progress on this, but there is still a fair way to go, according to Anton Eberhard:

  • Grid operators should be assisted with tariff modernisation
  • Arbitrary size restrictions on embedded generators should be reset based on rational technical and cost considerations. 
  • Permitting and licencing authorities must be held to their mandates and assisted and upskilled where needed.

If we can ensure that these factors are considered, there will be a hopeful outlook for South Africa’s electricity future. The alternative picture is not as sunny, as our power system could devolve into something undesirable for businesses and inequitable for South African citizens. 

How electricity generation has changed over the past 10 years – and what it bodes for our future

Alongside the global pandemic, electricity has been on many South African’s minds this year. And rightly so: South Africans can expect a 15% increase in their electricity costs from mid-2021, based on a recent court ruling which grants Eskom the right to recover operating costs through additional tariff escalations. This will mark more than a decade of average annual increases of 14%, relative to average inflation of just under 6%.

These escalations have fundamentally changed South Africa’s economy: the manufacturing and mining sectors have been particularly affected by the rising tariffs, and are doubly affected by the inconsistent supply caused by load shedding. South Africa’s electricity supply from the grid is subject to decreasing reliability, with 2020 already shaping up to be the worst on record for load shedding.

What South Africa is experiencing is not unique, but exposes the global trends that expose the high costs of maintaining an aging and centralised coal fleet. A decade ago, average Eskom tariffs were two times lower than they are today, and the costs of installing solar PV were two to three times higher. That situation is very different today: Eskom and municipal electricity tariffs are now substantially more expensive than solar PV installations on an average, lifetime cost basis. This is driving strong uptake of own-use solar generators, despite persistent policy and regulatory barriers.

This is because the electricity market has fundamentally changed over the last 10 years. The growing cost gap between the grid and solar PV means that the benefits of solar are more economically viable, even if the PV plants generate more power than required (for example on weekends, when a factory does not operate). 

For private electricity consumers, solar electricity is typically used to offset daytime electricity consumption through ‘own-use’ or ‘embedded’ generators that service the electricity needs of the facility on-site. The uptake of embedded solar generation has exploded in South Africa, particularly amongst the retail and manufacturing sectors, because of the cost savings generated by the plants. Despite this, embedded generators are largely restricted from selling power into the grid, although it is looking hopeful that this might change

The fact that solar PV is so much more affordable than Eskom’s grid is also changing the way in which solar PV is consumed by large commercial and industrial facilities. For example, some facilities choose to oversize their solar PV system relative to on-site electricity demand in order to increase morning and afternoon solar electricity production, generate more power in winter, save more diesel during load shedding, reduce peak grid demand charges, and achieve higher overall reductions in grid electricity consumption. 


Other commercial and industrial facilities are opting to oversize their solar PV systems and store the excess affordable power in battery banks – something that, 10 years ago, would have been ludicrously expensive. However, with Eskom’s tariffs increasing the way they are, and with the reduction in the costs of energy storage components, the business case is starting to emerge. The advancement in electricity generation technology gives businesses more flexibility and options when it comes to their energy choices. Own-use solar – whether on or off grid – is an affordable and, by now, well-used option.

Solar for mines

How solar for mines helps to reduce operational costs and achieve a lower carbon footprint

Reliance on third-party infrastructure a significant risk for mines

The outlook for the mining industry in South Africa was a mixed bag in 2018 with bulk commodity prices continuing to rise from their lull at the beginning of 2016, while precious metals continued to struggle. Cost increases have put the mining industry under significant pressure and although price plays a crucial role in profitability, there are large fixed-cost elements associated with mining. Thus maintaining and ensuring optimum production levels plays a significant role in achieving profitability. 

This is why reliance on over-stretched third-party electricity suppliers such as Eskom can compromise profitability. In PwC’s annual publication highlighting trends in the South African mining industry it was reported that one of the significant subcategories driving risk is reliance on third party infrastructure with the cost and availability of electricity and water still a concern.

Mining facilities that typically rely on diesel electricity can use a solar microgrid to reduce the overall cost of energy, increase energy resiliency, thus ensuring control of their energy and power requirements. SOLA’s energy storage services department has considerable experience in combining battery storage solutions and existing generators in microgrid systems ensuring a continuous, uninterrupted electricity supply which is integrated with all other power sources.

Mining Data Tool

Namibia and Botswana considering a 20-year, 4.5 GW solar push

‘The market for electricity produced by the mega-solar projects in Botswana and Namibia includes 12 other countries in the region that could be connected via new and/or upgraded transmission infrastructure,’ – WEF

The World Economic Forum’s (WEF) Global Future Council on Energy, has revealed that the governments of Botswana and Namibia are planning to develop 5 GW of solar capacity over the next two decades. Namibia and Botswana are considered perfect candidates for solar owing to their high solar radiation, strong legal and regulatory environments, suitable land availability and potential to host a low-cost, efficient electricity market to meet rising demand in the region. It has been suggested that this ambitious project, if completed, could lead to Namibia and Botswana exporting power to South Africa.

Botswana, a founding partner in a responsible mining initiative

Reducing carbon emissions is part of a global trend in the mining industry. Bloomberg reported last month that an explosive demand for renewable energy is expected to drive a global rush of exploitation, thus Botswana, the US, Australia and Peru are founding partners in an initiative to encourage responsible mining of rare earths and other minerals used in renewable energy projects such as solar panels, wind turbines and car batteries. 

Botswana’s mining industry contributes a third to the country’s GDP and 50% of tax earnings, and although the last quarter has seen a dip, economic growth is projected to pick up to 4.6% in 2020, supported by ongoing structural reforms aimed at diversifying the economy. It is perfectly primed to implement solar energy storage for mines owing to high solar radiation, the remote location of its mining facilities, weak grid supply and reliance on diesel.

Projected economic growth in Namibia in 2020

The IMF reports that Namibia’s economy will return to growth in 2020 after contracting for three straight years, though a failure to implement structural reforms could contribute to sluggish growth. Namibia has the second highest solar irradiation levels in the world, thus making solar energy storage for mines an appealing option.

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No longer a question of if, but when

‘Industries that aren’t moving towards zero-carbon emissions will be punished by investors and go bankrupt’

Industries that aren’t moving towards zero-carbon emissions will be punished by investors and go bankrupt, warned the governor of the Bank of England, Mark Carney, last week. Thus renewable and storage technologies present the perfect solution by reducing energy costs while improving power quality and lowering carbon emissions.

The climate crisis will have a real financial effect on all major industries. Last Tuesday Carney told large corporations that they had two years to agree to rules for reporting climate risks before global regulators devised their own and made them compulsory.

Energy autonomy or supplementing grid supplied energy with embedded energy generation are both solutions to optimising production costs and reducing carbon footprint. Solar PV is both a cost-effective and decentralised form of energy, making it perfect for mines and other large scale energy-producers choosing to supplement their supply.

 Off-grid solar provides the ideal energy storage solution for mines. Remote locations, weak grid supply and reliance on diesel provide the optimal business case for solar PV microgrid. To test if your mining facility is suited to making the switch to off-grid make use of SOLA’s user-friendly mining tool.

Try Our Mining Data Tool

Is solar energy suitable for my business?

You may have heard of solar PV – perhaps you even know other businesses that are using it. However, you might be wondering if solar PV is relevant for your business. It is worth considering that various factors affect the overall costs and tariffs of solar PV systems. 

Is solar PV right for my business?

At the outset, the best way to determine if your business could benefit from solar PV is by asking a few simple questions:

  1. Are you based in an area with good irradiation (solar resource)?
  2. Do you have a good quality, spacious roof or available open land near to your business?
  3. Do you use the bulk of your energy during the day?
  4. Are your reliant on diesel generators to keep your operation running during power cuts or because of lack of grid access?

If you answered “yes” to any two of the above, solar PV is definitely worth considering for your business. The aspects mentioned above are explored in more detail below. 

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1. Good solar irradiation

It goes without saying, but solar PV performs better under conditions with great solar irradiation. If you are based in Africa, you are lucky: Africa has some of the best solar irradiation in the world, so it is generally a no-brainer. However, there are a few factors that might influence the quality of irradiance, which could affect the overall PV system size and thus the cost.

  • Weather: Weather can influence the quality of the irradiance. Things like extreme heat and humidity can affect how well solar modules perform, making irradiance quality vary in different geographic locations.
  • Pollution: pollution in the form of smoke and gases or particles can lower irradiation; it can also collect on solar modules and reduce their efficacy. 
  • Shading: Factors such as large buildings, highways and trees can shade roof areas during the day, causing the solar PV to stop producing. If your solar PV engineering firm is reputable they should be able to carry out an extensive shading analysis. 

2.Roof space and quality

Rooftop solar PV is often the most cost-effective solution for Commercial and Industrial businesses. As such, the size of your business’s roof, including the type of roof and if it is structurally sound, is an important factor to consider when scoping out the feasibility of solar PV.

If your roof is not suitable for mounting solar panels, it is important to consider if there is land nearby that could house a ground-mounted solar PV solution. All of these factors can affect the cost, and therefore the feasibility, of solar for your business. 

Try Our Solar Feasibility Tool

3.Energy Demand and use

An essential factor to evaluating the efficacy of a solar PV system is energy demand and use. Two factors come into this: the business’s peak power (kVA) requirements, as well as its electricity use (kWh). If the business is a high energy consumer, especially if it runs 7 days a week, the costs of solar will likely be much cheaper. However if the business has large amounts of electricity usage at night, for example, it might make the cost of the system more expensive. 

4.Diesel generator usage

In Africa, many business operations rely on diesel generators in order to keep the power on, either due to weak or unreliable electricity grids, or because they have no access to the grid. In general, electricity generated by diesel is very expensive, making a solar PV microgrid, including batteries, a great way to save and cut back on this. 

Procuring solar: your options

If you are convinced that solar PV sounds like a good intervention, remember that the following options exist to procure solar PV for your business:

  • Buy solar energy directly – enter into a solar PPA in order to use solar PV electricity without any capital expenditure. The solar PV system belongs to SOLA, and you simply pay for the electricity that you use. The longer the term of the PPA, the lower the tariff over the system’s lifespan (20 years).
  • Build a solar PV system – purchase a solar PV system that your business will own, and simply pay for annual maintenance and upkeep. SOLA will design and construct the PV system for you, ensuring that it performs as predicted, and will maintain the system going forward.

Is solar feasible for my business?

If you spend over R100 000 (US$ 7000) on electricity per month, fill in some basic information in our Solar Feasibility Tool. We will evaluate the efficacy of solar for your business free of charge, and provide you with a few simple options to go forward, should you wish to proceed. 

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How to prevent loadshedding in commercial buildings

3 Options to proof your commercial and industrial building from load shedding

The nationwide spate of load shedding in South Africa is not just a highly frustrating situation for individuals: it is a hindrance to businesses and the economy in general. As South Africa starts to approach level 5 and 6 load shedding scenarios, it is important to look at the alternatives available to businesses around the country in order to prevent the loss of productivity across the board. At the same time, various different alternative sources of power should be evaluated based on their cost-effectiveness and environmental impact. The following article explores various load shedding prevention methods for commercial and industrial buildings.

Option 1: Using backup diesel generator

Option 2: Retrofitting a grid-tied solar PV system

Option 3: Going off grid using a solar PV/battery microgrid


Option 1: Using backup generators

This commonly used form of commercial backup power consists of diesel gensets that switch on when the power goes off. This is a good option for ad-hoc power cuts in places that cannot afford to lose power, such as hospitals, convention centres and large retail centres.

Before relying on a diesel backup generator, though, the system should be tested with the total load of the building to make sure that it is able to take the full electricity load. If it not possible for the gensets to handle the building’s entire load, an “emergency” scenario – where nothing but the critical systems are backed up – should be tested. An Automatic Transfer Switch (ATS) will be needed to ensure that when the power goes off, the diesel generators are initiated.

Within Eskom’s current loadshedding trajectory, using backup diesel generators is likely to be very expensive, depending on the load size of the building. Diesel itself is much more expensive per kWh than typical Eskom tariffs, and even more expensive when compared with the costs per kWh of solar PV. When evaluating the efficacy of installing diesel gensets, the following questions should be asked:

  1. How many hours per day will the genset(s) be required?
  2. How many litres of diesel are likely to be required?
  3. What are the ongoing maintenance requirements of consistently using diesel generators?
Robben Island has historically used diesel generators to provide the power needed on the island.
Robben Island has historically used diesel generators to provide the power needed on the island.

Option 2: Retrofitting a grid-tied solar PV system

In South Africa, many commercial buildings – hospitals, retail centres, distribution centres, etc – have grid-tied solar PV systems that supply power from the sun during the day. These relatively simple systems are tied to the grid, so they do not provide 100% of the offtaker energy requirement but rather supplement it. Unfortunately, grid-tied solar PV systems do not automatically prevent a building from experiencing load shedding.

Because solar generates Direct Current (DC) power, this needs to be converted into Alternating Current (AC) to be used in buildings as electricity. In order for a solar system to produce usable electricity, therefore, a solar inverter is required. However solar inverters are designed to switch off during a grid outage.

Why is this? For grid-tied solar PV systems, this serves as a vital safety mechanism for personnel that might be working on transmission lines during outages. With solar inverters off, buildings with solar PV systems are prevented from generating power during a grid outage and potentially exporting power to the national grid, which could be fatal for maintenance personnel.

Solar inverters are designed according to international safety standards that require this functionality, which means that grid-tied inverters cannot operate in off-grid conditions. As such, when Eskom goes down, most solar systems do, too.

However, this does not mean that large buildings with solar PV systems do not have options for load shedding. With careful engineering, It is possible to form one’s own “microgrid”, by replicating a fake grid-tied scenario to “trick” the solar inverters into staying on. This requires the use of a generator or battery, and specialised control equipment.

In order to retrofit a grid-tied solar system to operate during load shedding, two essential steps need to be taken. Firstly, the system needs to be isolated from the grid to prevent any exporting of power that could affect the safety of maintenance personnel. Secondly, a voltage forming source is required, in order to provide a reference voltage and frequency to the solar inverter.

Therefore, to prevent a grid-tied solar PV system from going out during a power outage, the following is required:

  1. Hardware that can disconnect the main supply from the grid, effectively isolating the building/facility from the grid.
  2. A diesel generator or battery bank that can provide backup power for the entire facility and provide the necessary voltage and frequency reference to the solar inverters.

These two points require careful engineering and a proper control system to manage the change-over, the dispatching of generators/batteries, and synchronisation of the solar inverters. It also has to oversee resynchronisation to the grid once the grid is available again. This can be automated and should not need any human input. Further, the system would need to be sized correctly in order not to trip under various loading scenarios.

With these two mechanisms in place, there would be a short down-time after an unexpected grid outage, due to the system having to switch itself on and switch to off-grid mode. Once switched over, however, the solar powered electricity which is being generated can be distributed throughout the building.

In order to avoid an outage entirely, it is possible to either isolate from the grid before an expected outage, or have an uninterruptible power supply (UPS) capable of providing continuous, uninterrupted power during an outage.

solar could help Africa's economy to grow

Option 3: Going off-grid: Using solar PV, batteries and Generators to go off-grid

Taking a commercial building off the grid entirely is another, although slightly pricier, option. Solar PV systems, when combined with energy storage, can store excess solar power produced during the day and distribute this later when needed. Solar PV is now one of the cheapest forms of energy, and its distributed nature means it’s perfect for use at source, where it is needed.

However, the costs of batteries and the sophisticated engineering of microgrid systems needs to be evaluated against the building’s requirements. Perhaps, a commercial or retail building operator does not mind paying a premium if that means consistent, clean power. (Microgrids also have particular relevance to supplying power in weak-grid scenarios – such as the one in Cedar Mill Mall which supplements the grid’s 250 kVA with an additional 250 kVA of power).

If your commercial or industrial building is currently using its diesel generators around 30% of the time, the business case for a solar PV and battery combined microgrid will likely look feasible. In a typical stage 4 load shedding scenario, power cuts generally occur for around 7 hours per day. Given the assumption that the energy load in the building is similar throughout the day and that diesel generators are being used to supply power consistently when the grid goes down, this would equate to around 30% of the total electricity consumption – making it a worthwhile investigation.

Whether it is a backup generator, installing a solar PV system with a backup generator or battery, or going entirely off-grid, there are options for commercial and industrial buildings in South Africa to prevent the damage that load shedding can do to business.

Cedar Mill Mall goes solar
Cedar Mill Mall in Clanwilliam is an islandable on-grid microgrid

Solar PPAs are an affordable way to access the benefits of solar electricity

5 FAQs about solar PPAs

In some of our previous posts, we’ve alluded to the benefits of a solar PPA: both as a way to provide more options for business owners wanting to go solar, and as a way of reducing costs in certain sectors. At this point, you may be convinced that solar finance is an affordable way to access green energy for your company, but you may have a few questions. In this blog, we explore the 5 most common questions about the most common form of solar finance, the solar power purchase agreement or PPA.

Why a PPA?

As we mentioned in the previous blog, a solar PPA usually enables an electricity consumer to utilise solar energy at a rate that is cheaper than the existing utility. In addition the ownership of the solar system remains with the PPA provider, and the user only pays for the electricity that they consume, rather than for the overall cost of the solar system – making it an affordable choice for several sectors. Below follow some of the most frequently asked questions about solar PPAs.

1) How long does a solar PPA last?

In fact, this question gets asked so often that we wrote an article about how long solar PPAs are already, and if you’d like a detailed answer to the question, have a look at that article. The summarised answer is, “it depends”. Whilst as a rule of thumb, the longer the PPA, the greater the  immediate cost-savings will apply, many businesses prefer to enter into a shorter PPA period for a higher tariff, after which time the system ownership is transferred to the energy user. It all depends on the requirements of the client, as well as the overall objectives of the project.

2) Do I have to own the building to enter into a solar PPA?

PPAs ideally take place between a building owner and an energy provider, since the construction and ongoing maintenance, as well as energy distribution throughout the building, will require the building owner’s input and buy-in. However, if the building owner agrees to make the rooftop available for the solar system and the agreement takes the building and end user into account, tenants may be able to enter into a PPA.

3) If it isn’t sunny, do I still pay?

Depending on the type of PPA agreement you enter into, you shouldn’t have to pay if the system is not generating energy (take into consideration though, that even on cloudy days solar systems generate a good amount of power). However, the opposite does apply: if it is very sunny and producing more than what the building is consuming, the client may be liable for a minimum payment for the energy that is wasted, should it not be used. That is why it is essential to ensure that the system is sized correctly.

4)What happens at the end of the PPA?

Depending on the type of agreement, the system may transfer over to the client who then will take ownership of the solar system. This could work well if the building owner wishes to take  ownership of the system after a period of time. However, there can also be “early exit” options, if the property owner is concerned that the building might be sold during the PPA term. Again, each situation is different, and when entering into a PPA it is best to check if the agreement contains provision to either buy the system, or to get the new building owner to assume the PPA, should the building be sold.

5)What is included in the PPA tariff?

Depending on the type of agreement you enter into, the tariff will include the costs of designing the system, procuring all necessary components, and constructing the system on the suitable rooftop or ground-mounted area so that the solar electricity is readily available for the client. The tariff also includes the costs of maintaining the system on an ongoing basis, such as cleaning and part replacement as needed. Typically, these combined costs will be similar, or less than utility based power when comparing on a per-kWh basis.

Are you interested in finding out more? Contact our solar finance department to learn more about our solar financing options.