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Tag: Solar Panels
BlueSolar vs SmartSolar
When buying Victron MPPT solar controllers you have two product lines to choose from, the BlueSolar range and the SmartSolar range. The key difference between the two is that the BlueSolar range does NOT have Bluetooth. The SmartSolar range has the smart features and can connect to your phone via Bluetooth. Yes that is definitely confusing, that’s why this tech-tip exists.
If you have happened to purchase a BlueSolar solar controller and want to change settings or add Bluetooth to it you can. You just need to purchase a VE.Direct Bluetooth Smart dongle. This will add the Bluetooth functionality to your device. You can also plug the controller into a Cerbo if you want an even cooler, more advanced setup.
Products which add Bluetooth functionality if you have a BlueSolar controller.
Rail Profiles
We help a lot of customers with solar rail and solar panel mounting hardware. Sometimes people need to match rail or mounts with their existing system. In order for us to help you out best, it is always a good idea to bring a photo or sample of your mounting gear. The images shown above give you an idea of the various types, of very similar looking, solar mounting profiles.
The Grace style and Clenergy branded rails are the most common types of rail that we sell currently. We do, however, stock a large range of new and used profiles and mounting hardware to suit a wide range of brands and profiles.
Parallel VS Series: the solar panel edition
When panels are in series the voltage adds up and the current remains the same, whilst in parallel the voltage remains the same and the current adds up, the wattage will always increase in both configurations.
For example:
Four 250W panels with the specifications of 45Voc and 5A (Isc) in series will total to 1000W, 180Voc and 5A (Isc).
Four 250W panels with the specifications of 45Voc and 5A (Isc) in parallel will result in 1000W, 40Voc and 20A (Isc).
A couple of useful bonus tips:
- Panels should always be matched, e.g. the same Voc, Isc and wattage.
- Check the specs of your solar controller and be careful not to exceed the max Voc, Isc and wattage.
Heat & Solar Panel Performance
It’s the middle of summer. It’s hot. Solar radiation is at it’s peak, but your solar panels are not quite performing at their peak. If you’re wondering what could be going on, our tech team are here to explain.
PV cells work mostly on the visible spectrum, the irradiance is what is important and the heat works against us reducing efficiency.
Panels are tested at 1000 W/m2 at 25ºC to determine peak power rating. Each degree above this rating affects the panel output performance by 0.38% on average (check your panel spec sheet for the exact figure for your panel). Monthly average temperature variations can result in fluctuations in panel performance.
If you want to know how much of a fluctuation is possible check out image 2. You can see that the percentage loss due to summer temperatures is way higher than winter.
Even though the power yield is higher in summer, this is also true for inefficiencies.
Tilt Angle & Performance
If you want to maximise average performance across the year, you should have your solar panels at a specific tilt angle depending on your location.
- In Perth the best angle is 30º, the same as in Brisbane and Alice Springs.
- Further North in Port Hedland you’re looking at 25º, the same as Townsville.
- Down South in Albany, 35º is ideal, an angle shared by Adelaide, Canberra, Melbourne and Sydney.
- At either end of the tilt angle spectrum in Australia sit Darwin at 20º and Hobart at 40º.
We sell a variety of tilt frame options to help you optimise your panel performance. If you are someone who has more than enough performance in summer but are looking to boost winter performance, you can even add 5 degrees to your tilt.
What’s the difference between solar panel types?
With a wide variety of solar panels available, understanding their differences and benefits will help you find the most suitable panel to meet your needs. The following four panel types are the most common varieties we stock at Alt-Tech.Â
Shingled Cell Solar Panels:
A Strip-over-strip design boosts power per SQ meter, no busbars and increased sunlight exposure. Reduced potential of micro-cracks.Use Case:
Limited space applications where generating the most power possible is imperative.Monocrystalline Silicon Panels:
A popular choice for decades, pure crystal cell formation results in slightly greater efficiency. Dark black appearance.Use Case:
Residential and commercial applications.Polycrystalline Solar Panels:A cost-effective choice due to quicker production. Good for mobile applications as they are generally corrugation resistant.
Use Case: Common in residential installations.
Thin Film Solar Panels:Less efficient per SQ metre but excellent performance in low-light conditions. Thin film’s are less affected with temperature and shading.
Use Case: Low light sites with good amount of space to mount them.
Second-life panels are our preferred choice and we always have a range of thin film, poly and mono panels in stock. Only new shingled cell panels are available at present, due to being newer technology.
Our knowledgeable sales team are always ready to offer further advise on the best panels for your system.
Shop Solar Panels
Solar Panels
We stock a massive range of new and second life panels, assessed and covered by five year warranty, offering affordable, reliable options for your off-grid solar project.
Over 80% of the solar panels we retail are second-life or warehouse seconds. This means that availability of specific panels is unpredictable. Stock levels listed reflect real-time availability and if levels are lower than your requirements, your best option is to choose a different panel. It could be six months, a year, or we may never receive more of a particular panel.
For more information on second-life and warehouse second panels, please check our FAQ.
Why are Solar Panels Overstacked?
Over sizing your solar panel array in conjunction with the right solar controller is a strategic move that promises several advantages, especially to deal with harsh winters, frequent cloudy days, or panels that might face dust and age-related efficiency loss. Also, panels are rated using artificial light that’s 1000W/sqm at 25C, scenario that highly differs for real life use.
Here’s why this approach is a savvy choice:
Take, for instance, a Victron 100/20 MPPT controller. By connecting four 250W panels in a 2S2P configuration (~74V Voc & 18.5A Isc) to charge a 24V battery bank, you maintain constant energy input, yielding roughly a fairly constant 480W output. This means during the bulk of daylight hours you’ll produce a constant 20A (max output of MPPT).To make the most of oversizing, it’s crucial to pair your solar panels with an appropriate solar controller that can handle the extra capacity. This ensures optimal energy conversion and management.
Shop Solar
Solar
Our warehouse is full of solar PV panels, rail and mount to suit all kinds of off-grid applications from 4WD, camping & campervans to tiny homes, shacks, agricultural and rural properties. Over 80% of the solar panels we retail are second-life or warehouse seconds. We believe these high-performance products should fulfil their complete functional lifecycle. Panels arrive assessed and we provide a five-year warranty because we are confident in their capabilities. 

These are the more sustainable and green option in alignment with our circular economic principles.Availability of specific 2nd life or warehouse seconds panels is unpredictable. Stock levels listed reflect real-time availability and if levels are lower than your requirements, your best option is to choose a different panel. It could be six months, a year, or we may never receive more of a particular panel.
What if my panels don’t match?
Mismatched panels can be put together in the same string, but there are some rules to follow to keep the system safe and efficient.
In a series string, you need your panels to be the same technology, similar output, and a similar open circuit Voltage. The limiting factor with series panels is the current – if you have a low current, high voltage panel in series with a high Voltage, low current panel, it will limit your output current and potentially overheat the low current panel.
For parallel strings, your panels must be the same technology, your parallel strings must be as close as possible to the same open circuit Voltage (5% out is considered the safe limit), the tilt angle must be within 5%. This is if they are ‘paralleled’ on the roof, without a breaker in between or power conditioning equipment such as micro – inverters.
If you have multiple parallel strings going through breakers, they still need to be the same technology and within 5% Voc, but they may be facing different directions / at different angles.
Are these 12V panels?
In industry, panels that are under 25V open circuit are commonly referred to as ‘12 Volt panels’, which leads people to think that if they have a 12V battery, they need a ‘12 V panel’ (which is actually 24V). Not the case.
There are two basic types of solar controllers – There’s a whole other tech talk on them but it boils down to:
PWM: Can halve the Voltage coming from the solar panel (so can bring 24V down to 12V). Not very efficient, not very good for your batteries in the long run as they tend to let through high frequency Voltage ‘spikes’.
MPPT: Can handle much higher Voltages (Most ‘12V’ MPPT’s take between 45 and 100V max. input). More efficient. Often comes with 3 – stage charging, takes excellent care of your batteries.
This means – With an MPPT, any panel you like can be a 12V panel. Generally speaking, getting a secondhand commercial grade house panel and an MPPT controller is going to cost about the same amount of money as a brand new 12V panel with a PWM (there are good 12V panels and there are also extremely bad ones), and will take better care of your batteries.
What’s the difference between monocrystalline and polycrystalline panels?
Record–breaking efficiency belongs to the monocrystalline panels, but generally speaking a 200W monocrystalline will be the same size as a 200W polycrystalline. Monocrystalline panels generally do better in the heat, polycrystalline panels genrally do a bit better in diffuse light conditions (i.e. partial shade)
What’s the best flexible panel
There are three main types of solar panel cell. Monocrystalline, polycrystalline, and amorphous.
Monocrystalline and polycrystalline are made from silicon wafers. Whilst a few brands like Sunpower have made more flexible cells, all mono-and-polycrystalline cells are brittle. A mono or a poly flexible panel is simply not going to last very long. You’ll get longer if they are framed or if they are mounted well, but you will be lucky to get 5 years from a good one and they often don’t last 2.
Amorphous flexible panels exist. Amorphous solar cells are very flexible and durable, and amorphous flexible panels are very expensive.
Solar panel wiring
When you have two or more panels, there are a number of ways to wire them up.
We are often asked – ‘What’s better? Putting our panels in series, or in parallel?’
(tl;dr at the end)
Series
Putting panels in series is just like putting battery cells in series – You plug the positive terminal of one panel into the negative terminal of the other. This adds the voltages together (so two 50V panels in series will give you 100V), and the Current from the two panels stays the same. Remember – Power is current multiplied by Voltage, so whether you put them in series or parallel, you are still getting the total power of Panel A + Panel B. There is a common misconception that more amps = more power, but this is not the case if it comes with a reduced Voltage.
Pros: In order for your solar controller to start charging, the Voltage from the panels must be higher than the Voltage of the battery system (In the Victron MPPT’s, at least 5V higher, but it varies from unit to unit). This shouldn’t be a problem with a 50V panel and a 12V battery, but on a cloudy day, early in the morning, and late in the evening, a higher Voltage is going to put more juice into your batteries, even if the total power of the panels is the same. (i.e. 400W of solar at 100V will give you more charge than 400W of solar at 50V, on a day when conditions are cloudy)
Cons: Series panels are very vulnerable to partial shading. Within the panel, your cells are also in series, so if you shade a single cell, it blocks some of the current going through the whole circuit, and the panel also starts to heat up which reduces efficiency. If you have two panels in series, it blocks the current going through both, so shading a single cell on one panel can dramatically reduce the output of the whole string.
(Note: there are various design features used in panels to mitigate the effects of partial shading such as bypass diodes and multi – busbar technology – so take this as a general statement)
Parallel
To put two panels in parallel, you put the two positives together, and the two negatives together. The most common way to do this is to use an MC4 double or triple branch adaptor (pictured), though the same behaviour applies if they are hard wired on the roof or if parallel strings are combined at a busbar closer to the solar controller.
Pros: If you partially shade one panel, it only reduces the output of that panel. Generally, partial shade won’t significantly decrease the output Voltage (depending on severity), so the shaded panel will continue to operate at reduced output and the unshaded panel will continue to operate at full capacity.
Cons: Under uniform low light conditions (cloudy days, early in the morning etc), your output Voltage will be reduced, which will limit charging.
Summary (Tl;dr):
No shade: Panels should go in series, as long as they stay 20% under the rated maximum voltage of the controller. Partial shade: Put them in parallel, as long as the output Voltage is going to be higher than your battery Voltage.
