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Question of the Day

Welcome to a new section of our website. A more informed consumer is a happier consumer, and we have plenty of expert advice to pass on. This section will grow as our we answer questions. Come back often to view new Q&As and follow us on Facebook for the Question of the Day.

How long will my solar panels last?

All Sinetech’s solar panels come with a manufacturer’s warranty (against defects) and a performance warranty. We only source from suppliers with a solid footprint in our industry.

In panels of 150W and higher, the manufacturer’s warranty is 10 years, and the performance warranty is 25 years, and what this means is that after 25 years, your solar panels will still be producing at least 80% of the power they were capable of producing on day one.

And this performance warranty is likely to be extended by manufacturers the longer their solar panels are in the field.

Some of the earliest models, from 40 years ago are still working at 80% efficiency today!

Can I mix and match solar panels?

Multiple solar panels are combined to increase the solar-generated power of a system.

Connecting different solar panels in a solar array is not recommended since either the voltage or the current might get reduced. This leads to lower output power, and thus to less solar-generated electricity – not to mention a waste of money: combining a 270W panel with a 150W panel will not result in 420W of solar power, but rather the system will not work or damage to equipment can occur.

From the outset, it must be noted that you should never mix solar panels that employ different technologies, ie polycrystalline and high-voltage CIGS thin-film. Stick to one type of panel.

If you must use solar panels from different manufacturers, you will need to carefully consider each panel’s electrical parameters (voltage, wattage, amps) and try select ones with a similar voltage and current. You will also need to factor in the performance degradation of each brand before combining them in a system.

And always consult with solar professionals like Sinetech before going ahead with any project; you can contact our technical consultants for advice on 011 886 7874 or by writing to sales@sinetech.co.za.

Why does battery cable come in different thicknesses?

You must select the correct diameter battery cable to handle the current of your battery. For instance, 100A can only be passed through a cable of a certain diameter.

If you choose a cable that is too thin, you will not be able to push the correct current through to charge your batteries. A cable that is too thick will not result in any negative consequences.

Something that can be dangerous, however, is making your battery cable too long. As the wire length gets longer, electrical resistance builds up until it forces the voltage down below a usable level – and the more electrical resistance that builds up, the more heat that is generated, which could lead to an electrical fire.

If you are going to need longer battery cables, you will need to compensate by choosing a thicker diameter of cable to guard against voltage drop.

Sinetech sells battery cables in various diameters and lengths; if you are not sure which cable is right for your application, call 011 886 7874 or email sales@sinetech.co.za

What is peak surge wattage?

The manufacturer’s label on most inverters gives two capacity values. The “continuous wattage” is the AC power output the inverter can supply for as long as the DC input (the battery) lasts. The “peak surge wattage” is the AC power output the inverter can supply for a short time period, dependent on the inverter make and model.

Peak surge capacity allows us to run items like fridges. Let’s say your fridge has a running wattage, or continuous wattage, of 600W. A fridge motor also needs a jolt of about three times its running wattage to start up, but this surge is needed for only a fraction of a second. To run this refrigerator, you will need an inverter that can handle 600W for long periods and a surge of 1800W for a brief moment.

The more information you give us on the items you wish to power, the better we can advise you. Contact our technical sales department on 011 886 7874 or email sales@sinetech.co.za for assistance.

Why are modified sinewave inverters cheaper than pure sinewave inverters?

All power inverters convert DC (direct current) power (which is power stored in batteries) to AC (alternating current) power, which is the power supplied by Eskom and fed to your home. Electronic devices need AC power to operate, but power inverters generally output power in two forms, modified sine wave and pure sine wave.

Pure sine wave power flows in even, arching waves that echo how power is supplied from a utility, whereas modified sine wave power flows to your devices in chunky, square waves. The square waves are giving power to your device in an “all or nothing” fashion. Your device will run properly, or not.

In short, the total harmonic distortion is higher in modified square wave inverters, therefore motors will run hotter (less efficiently, consuming up to 30% more energy than with pure sinewave inverters), and will likely not last as long.

Additionally, a modified or square wave inverter will often cause a “buzz” to be heard from audio devices and sometimes other appliances such as ceiling fans and microwave ovens.

Some devices and appliances that require a pure sine inverter are:

• Microwaves
• Laser printers
• Variable speed tools
• Cordless tool battery chargers
• Some TV’s
• Key Machines
• CPAP machines with humidifiers
• Medical equipment
• Sensitive electronics

If you are unsure whether your device or appliance will run on modified sinewave, make sure before you plug it in: speak to Sinetech’s knowledgeable technical consultants on 011 886 7874 or sales@sinetech.co.za

What is the purpose of an energy audit?

An energy audit will most often be performed when a client wants to install solar panels with a battery bank. It is not enough for your installer to know how much power you use, it is also important to know when that power is being used ie is that power being consumed during sun hours or at night.

The energy audit will guide our engineers to spec a solar array that is large enough to cater for your direct power needs during the day while also being big enough to charge your battery bank for use at night and during power outages.

Write to sales@sinetech.co.za to enquire about an energy audit on your premises.

How long will my batteries last?

Different battery types are designed to do a certain number of cycles at a specified depth of discharge.

A cycle is defined as one discharge and one recharge of the battery.
Depth of Discharge (DoD) means how deeply you drain that battery with each use.
In standby and solar applications, Sinetech recommends a DoD of 50% for lead acid batteries.

The Royal Lead Acid Batteries are designed to do this 800 times at a 50% DoD, and AGM+Gel Lead Acid Batteries offer 2250 cycles at 50% DoD.

Lithium-Iron Batteries like the PylonTech are rated to perform 4500 cycles at a 90% DoD – so you can discharge them much more deeply before you need to recharge them and power your devices for longer.

Most datasheets will include graphs like this one, where you can see the correlation between DoD and expected cycle life.

Of all the components in your system, batteries are the one item that requires the most care: always study the battery care sheet or manual that comes with your batteries and read our tips to keep your batteries performing at their best.

How do I care for my solar batteries?

Batteries should be housed in a well-ventilated battery cabinet to prevent dust and dirt from settling on them, and to keep them out of reach of children and unauthorised personnel.

They should not be positioned in an environment that is too warm – for gel, this is anything over 25 degrees Celsius and for lithium, this is anything over 45 degrees Celsius.

Undercharging and overcharging your batteries can destroy them; be sure to read the manufacturer’s care sheet thoroughly before you install your batteries.

If your batteries are going to be stored for long periods, without being connected to a system and in use, Sinetech recommends that you charge them every 3 months to prevent capacity loss.

It is highly recommended that you select an inverter which offers built-in temperature compensation.

Can I add new batteries to my existing battery bank?

In the case of lead-acid batteries, you should never mix old and new batteries in a battery bank. Your older batteries will be detrimental to the health of your new batteries and you will be wasting good money.

That’s because the diminished capacity of your existing batteries will cause your new batteries to work harder than the manufacturer intended, aging them prematurely.

And your new batteries will be trying to force more electricity through the older batteries than they are designed to handle; this could cause your older batteries to overheat.

When it comes to lithium-iron, you can safely build onto your battery bank in stages or modules, as long as you are using batteries of the same brand, model and voltage.

In both scenarios, you should never mix and match batteries – any batteries that form a battery bank must be from the same manufacturer, the same model, the same voltage and the same Ah.