Solar PV: Concerned about lead-acid battery longevity?

Solar PV: Concerned about lead-acid battery longevity?

By Bevan Jones, Technical Director at Soltra Energy

One of the most effective ways to prolong the life of lead-acid batteries used for energy storage in solar PV applications is to install a battery monitoring/ balancing solution.

In solar PV applications the batteries are regularly cycled – charged during the hours of daylight and discharged at night – which can have a detrimental effect on their longevity. This is the result of accelerated sulfation, dendritic growth, shedding (loss of material from the plates), electrolyte loss through gassing, decomposition of the electrolyte and a host of other negative issues that regular cycling promotes.

While the typical life of a lead-acid battery is between 300 to 500 cycles, it can be reduced considerably when batteries are subjected to deep discharges on a regular basis. On the other hand, battery life can also be extended with the use of a balancing solution.

The key to battery longevity – and reduced maintenance - lies in a thorough understanding of the status of individual batteries in a multi-battery pack in terms of their duty cycles and load factors.

While costly lithium-ion batteries are increasingly specified for solar PV and other applications where regular cycling is mandated, users should not be dissuaded from installing cheaper, lead-acid batteries when appropriate.

Today, ‘smart’ battery monitoring/ management technology is able to optimise individual battery performance on a 24x7 basis. A dedicated, computerised battery balancing harness is incorporated that automatically monitors a wide range of parameters associated with individual batteries in the pack.

Data streams containing information critical to the well-being of individual batteries, including temperature, state of charge and depth of discharge, are measured on a continual basis, while a tally of the number of discharge/ charge cycles is accurately recorded.

Battery performance can thus be balanced and equalised and should an individual battery’s operating parameters not meet design specifications or fail for any reason it is flagged for replacement, thus ensuring the integrity of the pack.

The technology featured in this modern battery management system not only distributes and balances the battery load as well as discharge and charge regimes across all batteries in the pack, it also takes steps to ensure that no battery is compromised through over-cycling or a malfunction of any kind.

Find us:

www.soltra.co.za

Don’t opt for solar energy before you’ve optimised your home. Part 2.

Don’t opt for solar energy before you’ve optimised your home. Part 2.

By Bevan Jones, Technical Director at Soltra Energy

Heating geyser water is typically the largest cost of energy in a home today. An average South African family will spend R10 000 or more to heat water every year.

In my last blog, I suggested that the next step to take before considering a state-of-the-art solar energy system is to install a modern heat pump to assist your geyser. Where a geyser uses three units of electrical energy to produce three units of heat energy, a heat pump converts just one unit of electrical energy into four units of heat energy.

What is a heat pump?

It’s a device that provides heat energy from a source of heat to a destination called a ‘heat sink’. Essentially, heat pumps move thermal energy opposite to the direction of spontaneous heat flow. Air conditioners and freezers are familiar examples of heat pumps which absorb heat from a cold space and release it to a warmer one.

A heat pump will use this principle to heat geyser water to 55-degrees C using hardly any energy.

A heat pump is relatively easy to plumb into a home or business. It makes use of a free renewable energy source, for example the air at ambient temperature in a roof, basement or storeroom which is drawn through a condenser to heat water. A typical heat pump is up to 370% efficient compared to 60-95% for a traditional electric geyser water heating system.

Heat pumps can also be retro-fitted to complement existing geysers or be used to support solar energy systems.

Installing a heat pump hot water solution is the next step towards optimising your home or business from an energy perspective. It will set you on the road to meaningful energy savings, ultimately transforming your living or work space into a much smarter version of itself.

Investing in a heat pump sets the stage for the installation of solar thermal panels or a state-of-the art solar PV energy system which will set you free from the hassles associated with regular power outages and grid unreliability.

It will also pave the way for you to monitor your energy consumption in real-time with a CarbonTRACK cost-reducing programme, giving you a better understanding of your electricity usage patterns and how to save money.

More details about the importance of solar energy, the future of home automation and the power of the Internet of Things (IoT) in my next blog.

Find us:

www.soltra.co.za

Don’t opt for solar energy before you’ve optimised your home. Part 1.

Don’t opt for solar energy before you’ve optimised your home. Part 1.

By Bevan Jones, Technical Director at Soltra Energy

Around one third of the average household’s monthly electricity bill is linked to the hot water geyser. Why does an electric geyser use so much energy?

The domestic geyser holds its water at a set temperature for 24 hours a day, 365 days a year. Most likely the setting is unnecessarily high. The default setting for most geysers sold in South Africa is around 65°C.

People don’t have 65°C showers but your hot water is maintained at this steaming temperature awaiting your pleasure. First thing you do is add cold water to get the temperature ‘just right’.

Not only is this inefficient, but most safety-conscious people will say it’s not safe to have tap water that hot when children or aged people are in the house.

Your geyser also uses too much energy because it is switched on when you don’t need it – when you are at work or sleeping. Moreover, geysers are inherently inefficient and use more energy than they theoretically should. This is often because the thermostat allows the water temperature to fluctuate between 55°C - 65°C, using unnecessary amounts of power in the process.

The first step towards optimising your home is to transform your ‘dumb’ hot water system into a much smarter version of itself with a CarbonTRACK system.

CarbonTRACK monitors your energy consumption in real-time, giving you a better understanding of your electricity usage patterns and how to enhance them. CarbonTRACK will regulate the heating cycle and put you in control.

For example, with CarbonTRACK you can remotely switch your hot water system on and off, set timers for its operation and change the default temperature (even a 10-degree difference will help you save without impacting your comfort) from anywhere in the world.

CarbonTRACK’s user dashboard allows you to track and benchmark your energy consumption and make informed decisions related to improving areas of inefficiency, helping you cut back on wasted electricity.

Once you’re on the road to meaningful energy savings with a CarbonTRACK, cost reducing programme, the next step to take before considering a state-of-the-art solar energy system is to replace your old, perhaps rusty geyser with a modern heat pump. Where a geyser uses three units of electrical energy to produce three units of heat energy, a heat pump converts just one unit of electrical energy into four units of heat energy. I’ll explain how this works in my next blog.

Find us:

www.soltra.co.za

Top 3 misconceptions about solar PV

Top 3 misconceptions about solar PV

By Bevan Jones, Technical Director at Soltra Energy

The past year witnessed a significant increase in interest in rooftop solar photovoltaic (PV) power for a wide range of domestic, commercial and industrial applications in South Africa.

Solar power – nature’s free alternative – is now seen as a cost-effective, ‘green’ solution, particularly when compared to noisy diesel- or petrol-powered generators.

However, there are a number of solar PV misconceptions that have gained currency. Let’s debunk them….

1. Solar PV provides a quick return on investment.

Incorrect. A solar PV installation is a long-term investment. Yes, it can be seen as an electricity price hedge and there is a possibility – depending on electricity price rises – that returns can be realised as soon as five years, but it is far more advantageous to view solar PV as a 20- to 30-year investment instrument – much like a mortgage bond on your house.

2. Solar PV presents an opportunity to cut ties with the grid.

No. A much better course of action is to maintain ties with the electricity grid. Not only will you be able to use the grid as a ‘big storage battery’ in the case of emergencies, it also offers a ‘fall-back’ option in the case of continuing cloudy weather.

3. I can feed back my excess energy into the grid and get paid for it.

This is not possible throughout South Africa right now. Let’s remember that implementing a feed-in tariff is a political process, which involves many interest groups including the electricity generating industry, financing institutions, the renewable energy industry and non-governmental organisations. This is not to say that small-scale rooftop PV installations have been excluded from the feed-in tariff concept, as there are municipalities that support partial schemes. NERSA, the National Energy Regulator of SA will hopefully provide more clarity in due course.

Find us:

www.soltra.co.za

2015: A year of solar power, battery technology advances.

2015: A year of solar power, battery technology advances.

By Bevan Jones, Technical Director at Soltra Energy

The past year witnessed a sharp uptick in interest in South Africa for rooftop solar photovoltaic (PV) power for a wide range of domestic, commercial and industrial applications. This was bolstered by an increasing determination on the part of consumers to reduce their reliance on Eskom.

Solar power – nature’s free alternative – is now seen as a cost-effective, ‘green’ solution, particularly when compared to noisy diesel- or petrol-powered generators.

Perhaps one of SA’s more memorable advances in the power provisioning field in 2015 was the development by Soltra Energy of a new installation paradigm for solar PV panels.

Soltra Energy is a leader in the field of solar PV power provisioning systems and infrastructures. Its innovative solution is set to provide businesses with more effective energy returns from rooftop solar PV solutions while boosting the often limited availability of Eskom power.

Conventional wisdom maintains solar PV panels should be orientated towards north in the southern hemisphere to allow for the most efficient power generation. The result, from a power production standpoint, is a ‘bell curve’ reflecting power increases throughout the day peaking at midday and gradually falling again to zero at sunset.

However, in a pioneering grid-linked hybrid solar PV application in Johannesburg, an east-west orientation was proposed by Soltra Energy, tested and found to be more advantageous in a business environment.

The motivation for the experiment was an Eskom electrical power supply unable to meet the business’ full demand. A complementary challenge was to reduce the aggregate electricity cost for the facility.

Soltra Energy initially evaluated power production from traditionally north-facing panels. Subsequently, various directions were tried culminating in a convention-breaking, east-west configuration which, in this application, provided significant cost advantages over a north facing system.

One of the keys to the success of the installation – and similar installations going forward - lies with its management. Sophisticated ‘smart’ power management solutions designed by Soltra Energy can now be installed and tailored to users’ needs.

These systems will, for example, complement grid power with solar power when necessary (at peak times), divert excess solar power to possible battery storage for later or after-hours use as appropriate, and engage an optional generator to integrate seamlessly into the power supply grid should battery storage become depleted.

Another breakthrough in this field in 2015 was the launch of a locally-designed ‘power wall’ lithium-ion battery pack solution and making it available to the local market ahead of a similar unit produced by US manufacturer Tesla.

Like its American counterpart, the SA-manufactured Soltra Energy Wall is designed to store excess energy, whether it is derived from the Eskom grid, from solar panels or a combination of both as found in increasingly common hybrid systems.

The attractive, space-saving unit represents a leap forward in battery storage and is expected to boost the acceptance of rooftop solar PV-plus-battery solutions in 2016 and beyond, giving SA consumers greater control over their energy usage.

Efficient battery storage could quickly become one of the biggest game-changers in the South African energy landscape, which will continue to be characterised by a mismatch between demand and supply. It’s a technology whose time has finally arrived.

Find us:

www.soltra.co.za

The Tesla Powerwall: We couldn’t wait, so we designed our own.

The Tesla Powerwall: We couldn’t wait, so we designed our own.

By Jack Ward, CEO of Soltra Energy

From what we’ve seen in the media, the Tesla Powerwall lithium-ion battery pack is an attractive, wall-mounted, space-saving unit that represents a leap forward in battery storage technology.

For users opting for solar energy installations, either to complement or backup Eskom power – or move off the grid completely - the Powerwall concept will certainly boost the acceptance of rooftop solar PV-plus-battery solutions beyond all projections. It’s a technology whose time has finally arrived.

While the Tesla Powerwall has been eagerly anticipated by South Africans facing disruptive power outages and the real possibility of load-shedding in the near future, the first Tesla units for general distribution in SA are reportedly some months away.

Fortunately for local electricity consumers, there is no need to wait. The alternative to the Tesla Powerwall is already on the market. Thanks to local design innovation and manufacturing excellence, the Soltra Energy Wall is available for immediate delivery. There is no waiting for a supply channel to be formed, personnel to be hired or stock to arrive.

One of the most attractive features of the Soltra Energy Wall – which assuredly mirrors its opposition in terms of specification and presentation – is the price. As can be expected, SA’s falling rand against the US dollar has caused the retail prices of US-made goods to soar. According to reports, final pricing for the Tesla Powerwall will likely only become available closer to the battery’s local launch date.

On the other hand, the SA-designed and manufactured Soltra Energy Wall – now available for country-wide installation - is cost effective and its price is easily justifiable for a wide range of applications. These range from domestic installations to the largest industrial sites where synchronised, multiple wall-mounted units and a unique, utility-scale, floor-standing version of the Soltra Energy Wall are ready for duty.

Most importantly, the Soltra Energy Wall is backed by a world-standard 10-year guarantee (subject to a 70% depth of discharge benchmark) and nationwide technical service by an existing, highly-trained and experienced customer support team.

While the Tesla Powerwall has been hailed as a game-changer, we can confirm that the locally-designed Soltra Energy Wall has already irreversibly altered the rules by which the power provisioning game is played in South Africa.

Find us:

www.soltra.co.za

  

Compare solar PV installers: Ask the right questions.

Compare solar PV installers: Ask the right questions.

By Jack Ward, CEO of Soltra Energy

 If you are considering a solar photovoltaic (PV) installation, you’ll probably be asking for quotes from a number of installers. Before you do, here are a few pointers to help you ask the right questions of the potential installers before comparing their costings and making a choice.

As you might expect, understanding the pricing structure of the installation as quoted will be a priority. An easy way to compare competing quotes is to ask the suppliers for their price per Watt (PPW). This is how professional contractors price out solar systems.

The PPW is the price for each Watt of solar energy you’ll be purchasing and it should be based on the completed system’s price, including VAT and other additional items. The ‘Watts’ element is calculated according to the installed DC Watts, which can be arrived at by adding the wattage of all solar panels to be fitted.

Don’t be confused by the fact that solar systems’ output is generally measured in kilowatts (kW) – simply multiply by 1000!

Some points to ponder:

• Make sure you compare ‘apples with apples’ by using the gross price of the installation including labour, materials, financial costs (if appropriate) and other overheads.

• Ensure that sure the specification meets your requirements. For example, do you need a domestic, grid-tied hybrid system without battery storage; or an off-grid system with batteries or something in-between. If you are running a business, you might opt for a solar/diesel hybrid system which should include a generator and an intelligent management system to automatically prioritise the power source as necessary.

• Are the Watts used in the calculation DC Watts? (Some quotes may detail AC Watts.)

• Bear in mind that some solar panels are better than others. Opt for Tier One, branded panels with warranty back-up but expect them to be more expensive than Tier Two panels or unbranded items from a fly-by-night supplier.

• The type of string or micro inverter selected can vary in price by as much as R4.00 per Watt.

Note that the biggest variance in price should be system size. However, as a system gets larger, not all costs increase proportionally.

Nevertheless, as a rule of thumb, your solar PV installation in South Africa should cost between R 20.00 per Watt for a grid-tied installation and R 40.00 per Watt for a hybrid alternative. Any price under or over this range should be closely examined for accuracy and supplier dependability.

Find us:

www.soltra.co.za