Best advice for solar PV installations

Best advice for solar PV installations

By Jack Ward, CEO of Soltra Energy

Rooftop solar photovoltaic (PV) solar systems are mushrooming around the world. In South Africa they have gained significant ground as users look to supplement Eskom power, combat load shedding or move off the grid altogether.

Over the past year, system components have grown more mature, capable and reliable. At the same time solar PV systems have become more price competitive and viable, particularly when seen in the light of spiralling electricity rates.

While small-scale solar systems are increasingly sold in hardware stores and builders’ supply depots, users should resist the temptation to effect a DIY installation. Here are just some of the reasons why:

Although most roofs can support the added weight of a solar energy system, some can’t. It takes a professional – preferably a structural engineer - to check the condition of the rafters and assess the capability of the roof to safely support the added dead load of the solar array, the mounting rack and the temporary live load imposed by the installation crew. (Unsurprisingly, the latter calculation is often omitted by DIY’ers.)

While the type of solar panels (be wary of thin film modules which have a lower yield) and the number to be installed will need to be professionally selected and calculated, it’s important to choose a manufacturer that will back its products with an optimum performance guarantee of 80% over a 25 year period and offer panels with an expected lifetime of over 30 years.

Note that the orientation (north–facing) and angle of inclination of the solar array are both critical for optimum performance. So is the spacing between solar arrays to allow channels for electrical cabling. Ideally, the array should be located near the main electrical service board if a grid-tied system is being installed.

Grid-tied PV systems should be interconnected by a licensed electrician while solar hot water systems (often employed in tandem with a solar PV system) should be installed by a licensed plumber.

Choosing a solar PV inverter also requires expert intervention. The inverter converts solar energy to electricity and will also have to be expertly sized and selected. Many inverters are energy wasters. Choose one that isn’t.

In most grid-tied installations, the building’s electrical demand may be determined and used to specify the inverter needed for the solar PV system. In other cases, however, the estimated peak array output is used as the basis for specifying the inverter.

In a remote or stand-alone solar PV system installation, the average daily electric load of the building needs to be calculated first. The building’s electric demand should include the Watt demand of all AC loads running at the same time, plus the wattage from the surge of starting motors, and all DC loads operating simultaneously. This demand should be further increased by a factor of 1.2 to 1.4 in order to account for inverter losses.

In both grid-tied and remote site situations, the initial estimate of the inverter’s capacity may be impacted by future plans, such as increasing the size of the PV array. This needs to be accommodated at the planning stage by a professional PV system engineer.

Eskom produces electricity that is a true sine wave. A modified sine wave inverter produces a slightly squared off electrical waveform, but some computers, power tools, refrigerators and most other powered equipment can use this generated electricity.

On the other hand, pure sine wave inverters produce a true sine wave that is the same as Eskom’s which is needed by high-end audio and other specialised equipment that are electrically sensitive, such as life support systems.

Importantly, in grid-tied installations the inverter must be able to be shut down rapidly in situations where utility power goes down. This is called anti-islanding and is a safety function for any Eskom personnel and electricians who may be working on the lines in the area.

An off-grid system will require storage batteries (the number and capacity are critical) and – usually – a backup diesel or petrol generator to take up the slack on cloudy days.

There are any number of economic studies that reveal how this calculations should be made and more about the long-term value of installing a solar PV system. But in the main, these studies are only as good as the input data. Make sure you are professionally advised when working with the numbers.

   

Find us:

www.soltra.co.za

  

Air pollution: Is Jo’burg poised to become the next Lagos?

Air pollution: Is Jo’burg poised to become the next Lagos?

By Jack Ward, CEO of Soltra Energy

When the lights go out in Lagos, Nigeria – which happens on a regular basis – the generators fire up. Gradually, like fireflies emerging from a slumber on a hot summer’s night, the city lights flicker and re-ignite.

With increasingly frequent electricity outages – load-shedding – being a feature of life in Lagos (as it is in Johannesburg), diesel exhaust pollution is also getting worse. Fumes from generators and heavy commercial vehicles now combine to raise air pollution to levels that can lead to respiratory and cardiovascular diseases.

While pollution levels in Johannesburg, the industrial heart of South Africa, may not have reached crisis levels yet, there are those who believe a Lagos-like scenario is not too many years away, unless steps are taken to avoid it.

Eskom’s load shedding schedule remains as relentless as ever, with no end in sight to daily electricity outages. The answer, for many South African businesses and homes, has been the installation of a generator.

It’s a short term solution. The price of diesel is on the rise, meaning that the costs of keeping the lights on will rise over time – much as Eskom’s prices will inevitably continue to rise.

For those who believe in keeping the air breathable – and the evenings noise-free – the promotion of green solutions to address a potential pollution problem is a priority.

In this light, there a couple of solutions that are immediately available. Let’s take the uninterruptible power supply (UPS) system. Eminently more ‘green’ than the diesel generator, the price of a UPS is determined by its size and the number of batteries in its battery-pack. Both play vital roles in determining the total number of hours of back-up time available.

An installation’s requirements depend on a number of less-than-obvious factors, such as the maximum possible load required, the average likely load and the level of redundancy that may be needed to be on the safe side.

One of the advantages of a UPS system is its ‘power conditioning’ effect or the removal of so-called spikes and brown-outs from the power supply. This is vital for sensitive computer equipment. The down-side is it needs electricity to charge its batteries.

Significantly higher up the ladder in terms of its ‘green appeal’ is solar photovoltaic (PV) power. Not initially considered as a stand-by power supply solution, solarPV plus battery installations are now gaining momentum, helped by improving technology and falling hardware and battery prices. The Tesla Powerwall is a clear example of how storage technology is advancing and prices are falling.

Grid-tied, hybridised solarPV plus battery installations are targeted at domestic, commercial and industrial markets. Ideal for rooftop installations, they offers backup battery autonomy and are thus geared for load-shedding.

What will save Jo’burgers from Lagos-like pollution is their readiness to accept rooftop solar PV power solutions against the backdrop of concerns over power reliability, price hikes and the lack of leadership as Eskom lurches from one crisis to another.

When comparing the cost of setting up a solar plus battery solution to that of Eskom’s rising prices, parity has pretty much been reached. Should Eskom receive the 12.69% increase it has requested for the 2015/2016 billing period, solar will represent better value for money.

This calculation is supported by the Residents and Business Owners Association of the Johannesburg suburb of Parkhurst which has launched an ambitious plan to become a model of self-sufficiency and green living by persuading 2000 homeowners to install full solarPV plus battery systems over the next five years in a bid to cut ties with Eskom.

It is becoming clear that the current trend is away from generators, as users embrace nature’s free alternative.

   

Find us:

www.soltra.co.za

  

Solar PV plus battery solutions: Prices poised to plummet

Solar PV plus battery solutions: Prices poised to plummet

By Jack Ward, CEO of Soltra Energy

I’m on record as saying that the Tesla Powerwall, the revolutionary wall-mounted lithium-ion battery-pack, will gain general marketplace acceptance faster than predicted.

The latest news from Tesla certainly supports this. At launch earlier this year, the Powerwall was cheaper than most industry watchers were prepared for, mainly because Elon Musk, the South African-born founder of Tesla, was determined to demonstrate the broad global acceptance of his brainchild.

Now, the prices for all variants of the Tesla Powerwall are falling faster than expected even before the first Powerwall has been shipped! For example, the average Tesla Powerwall battery price on launch was around US$ 547/kWh. Now it’s around $350/kWh and set to breach the $300/kWh price point soon. What will it be when worldwide distribution begins in 2016?

According to industry watchers, Tesla’s batteries are already seven years ahead of the market when it comes to pricing, giving tens of millions more customers the opportunity to cost-effectively install solar PV plus battery systems in their homes.

Consequently, when the customer-friendly, aesthetic, well-designed Tesla Powerwall makes its appearance in SA it will have a ready market waiting. Expect stocks to evaporate faster than water in a parched desert. Globally, reserve orders are mounting - around $800-million worth as we speak.

Why are prices falling so fast? It’s due to the battery’s application in the automotive market. In the US, electric vehicles are big business. Already more than 3 million electric-drive vehicles are on the roads. Tesla, BMW and now Mercedes-Benz are vying for the lion’s share of this burgeoning market.

Bringing down the cost of an electric drivetrain is therefore an important step in increasing the adoption of zero-emission vehicles. Vehicles sales are thus at the centre of this development.

Here, in electricity-starved SA, electric vehicles may not be a priority, but preparing for disruptive load-shedding and soaring electricity prices is. With Testla lighting the path ahead, cheap battery storage is set to boost the acceptance of rooftop solarPV plus battery solutions beyond all projections. It’s a technology whose time has finally arrived.

Find us:

www.soltra.co.za

  

How susceptible are rooftop solar panels to devastating storm damage?

How susceptible are rooftop solar panels to devastating storm damage?

By Jack Ward, CEO of Soltra Energy

How do solar PV panels stand up to the extremes of rain, wind and hail? What about their resistance to the fury of the typical Highveld thunder storm? It’s a good question, considering the expected lifespan of a solar PV installation is 25 years or more. It’s bound to see a good many storms in its lifetime.

Fortunately, the answer is certain panels – from reputable manufacturers - stand up very well to the rigours of harsh weather. The key is to select panel arrays capable of withstanding Mother Nature’s rage and ferocity at its worst.

Panels featuring tempered glass, for example, are particularly strong and long-lasting while amorphous panels, combining flexible plastic material, are highly resistant to hail damage and any harm that may occur (unlikely) will not substantially affect the array’s performance.

The strength of solar PV panels is measured and rated in a number of ways. The first rating is for static loading – usually applicable to snow loading - which shouldn’t interest us here in sunny South Africa.

What should interest us is the rating for wind loading. Wind is a much more dynamic force and can fluctuate in intensity rather rapidly. This is referred to as mechanical load.

Solar PV installation by Soltra Energy

While static and mechanical loading are tested in different ways, the combined force a panel can withstand is measured in Pascals (Pa). The normal test threshold is 2400 Pa, but it’s best to choose a panel capable of passing a mechanical load test of 5400 Pa – particularly if it’s going to be part of an array sited in extremely windy areas, such those found along the eastern Cape coastline.

By far the most impressive test of a solar PV panel is for its hailstone resistance. The Class 4 hailstone test (devised by the Renewable Energy Test Centre in California) subjects solar PV panels to multiple impacts from 50mm diameter hailstones – bigger than golf balls – frozen at minus 17degrees, at terminal velocities of 76 metres per second or a staggering 400-plus km/h. Panels that pass this test represent the very best available.

So, if you are in the market for a rooftop solar PV installation, take out good insurance in the form of a quality solar panel array from a reputable supplier and breathe easy for 25 years or more.

  

Find us:

www.soltra.co.za

  

Power storage for all with Tesla’s new Powerwall

Power storage for all with Tesla’s new Powerwall

By Jack Ward, CEO of Soltra Energy

One of the most exciting announcements in the renewable energy arena has come from Elon Musk, CEO and chief product architect of Tesla Motors, and chairman of SolarCity. 

His Tesla Powerwall battery system represents a game-changer in this industry sector. It is a development stemming from Tesla’s pioneering work in bringing affordable lithium-ion (Li-ion) batteries to market for the company’s successful electric vehicles - the Tesla Model X and Model S.

The Tesla Gigafactory - currently being built in Nevada in the US - will mass- produce these batteries, bringing a-step change in terms of reducing Li-ion battery costs to market.

How will this be achieved? Tesla will use its considerable automotive experience to package Li-ion batteries into attractive, space-saving wall-mounted units. The Powerwall’s design will allow batteries to be mass produced and installed safely in homes and businesses - by the tens of thousands.

Powerwall is a boon for the solar photovoltaic (PV) industry because it brings to market an electrical storage unit that’s three to four times cheaper than conventional lead acid-based batteries.

Technically, lead-acid batteries have not really improved since their introduction some 150 years ago.  Now, thanks to Tesla, every solar PV installation - grid-tied or not – should be configured around electrical storage with a view to significantly improving the availability of supply and the overall return on investment (ROI) of the solution.

Unlike lead-acid batteries that degrade drastically if discharged by more that 30-40%, depth of discharge (DoD) is no longer an issue with the Tesla Powerwall. 

Li-ion holds great promise, as the battery can be fully discharged in every cycle. What’s more, the Tesla Powerwall will last as long as 20 years and comes standard with a 10-year guarantee.

Good news is that in South Africa there is currently no import duty on Li-ion batteries (unlike automotive lead-acid batteries) bringing solar PV systems ever closer to economic viability and parity in terms of costs with increasingly expensive Eskom power.

Find us:

www.soltra.co.za

  

Electricity consumers search for new solutions

Electricity consumers search for new solutions

By Bevan Jones, Soltra Energy MD

In the face of Eskom’s supply uncertainty and price hikes, consumers are on the lookout for new, innovative alternatives. This was evident at the recent Power & Electricity World Africa 2015 show in Johannesburg where Soltra Energy took the opportunity to launch its new high capacity Soltra GTB 10 000.

This is a 10 kVA capacity, utility grid-connected, hybrid solar photovoltaic (PV) power system suitable for small-to-medium-size enterprise and domestic markets. Ideal for roof-top installation, it offers a greater degree of backup battery autonomy and is thus geared for load-shedding.

Our belief, that the Soltra GTB 10 000 is a good fit for consumers’ current mind-set, was borne out at the show by the many interested visitors who took time to call at our stand.

They confirmed what we already believed: There is burgeoning interest in rooftop solar PV power solutions for domestic, commercial and industrial applications. It is gaining momentum on an almost daily basis as our parastatal power provider lurches from one crisis to another.

Without doubt, consumers from all sectors of the economy are keen to reduce their reliance on Eskom. Concern over power reliability, price hikes and the lack of leadership at the highest levels was reaffirmed by almost all our visitors.

It became crystal clear that the current trend is away from generators – which are often seen as too noisy for domestic use. Solar power - nature’s free alternative - is gaining ground as it is becoming an attractive, cost-effective solution, particularly when Eskom’s new pricing structures are taken into account..

In this light, our new Soltra GTB 10 000 functions as a back-up rather than a complementary power source in the event of a power outage. This sets it apart from conventional solar PV power systems.

For the technically minded, the 10 kVA capacity unit is a hybrid solar PV power system that can be operated in three modes: linked to the electricity grid (grid-tied); as grid-tied unit with battery backup (in a hybrid configuration); or as a stand-alone hybrid unit. In line with uninterruptible power supply (UPS) and other conventional solutions, switchover time from mains to batteries is a rapid 15 milliseconds. 

Find us:

www.soltra.co.za

  

Ground-breaking solar PV solution on show at Power & Electricity World Africa 2015 - Sandton Convention Centre, 24/25 March.

Coping with load-shedding?

Ground-breaking solar PV solution on show at Power & Electricity World Africa 2015 - Sandton Convention Centre, 24/25 March. 

By Bevan Jones, Soltra Energy MD

Eskom’s “crazy deal” in which it will pay well over the odds for high quality coal that its power stations cannot use unless it is blended down in a costly process is yet another indication that South Africa’s power utility is out of step with reality.

Five million tons of expensive, export-quality coal from Glencore mine will cost Eskom R3.76-billion a year – money it does not have.

Where will Eskom get the cash? The answer, most likely, is “from electricity users”. That’s out of your pocket….

For businesses and households, the future could be bleak….. unless there is an uptake of solar power, nature’s free alternative.

At the upcoming Power & Electricity World Africa 2015 show (at the Sandton Convention Centre on 24 - 25 March) a new, ground-breaking solar PV solution will be under the spotlight on the Soltra Energy stand.

Dubbed the Soltra GTB 10 000, the device functions as a back-up rather than a complementary power source in the event of a power outage. This sets it apart from conventional solar PV power systems.

For the technically minded, the 10 kVA capacity unit is a hybrid solar PV power system that can be operated in three modes: linked to the electricity grid (grid-tied); as grid-tied unit with battery backup (in a hybrid configuration); or as a stand-alone hybrid unit.

Aimed at larger-sized installations and ideal for roof-top installation, it offers a greater degree of backup battery autonomy and is thus geared for load-shedding.

In line with uninterruptible power supply (UPS) and other conventional solutions, switchover time from mains to batteries is a rapid 15 milliseconds, suitable for protecting sensitive computer and other delicate equipment from the frequent power ‘brownouts’ and ‘spikes’ so common today.

Take time to visit the Soltra Energy stand at Power & Electricity World Africa 2015 where you find today’s solutions for tomorrow’s power problems – and knowledgeable people with whom to discuss your requirements.

Find us:

www.soltra.co.za