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iWolf Solar Power Solutions.
ABB, Accurate Solar, Apparent, APS, Array Converter, Azuray Technologies, Delta, Direct Grid, Exeltech, Enphase, GreenRay Solar, Kaco, Larankelo, National Semiconductor, OKE/SMA, Petra Solar, Plug & Power, Sparq, SWEA and Tindo Solar.
In Australia, Enphase, APS, ABB, Tindo and Delta are considered the market leaders.
Seven things you should consider when choosing a solar system.
1) What are the two most common types of Solar Energy.
2) How as a Solar Power system connected to the Grid.
3) Is an Off Grid Solar System right for your.
4) Solar Panels. Avoid Cheep Knockoffs.
5) Calculate how Much Solar Power I Need.
6) Are Micro Inverters and AC Solar Panels the future of solar power.
7) DC Optimisers
The two most common types of Solar Energy
If you are looking for a solar solution to power your home or business, you need to consider the options:
If it’s solar hot water heating you are looking for, then Solar Thermal is what you need for smaller applications. Solar Thermal uses the sun’s heat directly to heat up another medium, usually water, air or conductors without using electricity. Solar hot water systems use flat plates or tubes to capture the sun’s heat. Solar thermal is typically used to boost the production of hot water.
Solar Photovoltaic, also known as Solar PV
However, if you want to generate your own electricity, you are going to need a Solar Photovoltaic system. Photovoltaic is usually abbreviated to PV or Solar PV.
Solar PV panels are often referred to as ‘solar cells’ although solar cells are actually the small squares within the solar PV panel. Most solar panels look ‘bluey-black’ in colour and are usually installed in groups called “solar arrays”. A typical Australian installation these days averages around 4000 watts (4kW), and a typical panel is 250W.
How Solar Electricity Works
There are 5 core components used to build a solar electric system and connect it to the Grid.
- Solar Panels
- DC-AC Inverter
- Emergency Disconnect Switch
- Fuse-box link box
- Electricity Meter
1. Solar Photovoltaic Panels
Taking up to 60% of the cost of your solar electric system, photovoltaic (PV) panels are the most expensive component.
Solar panels are used to absorb sunlight and convert it into low voltage, direct current electricity. Inverters are used to raise the voltage and make it usable for everyday appliances.
2. DC to AC Inverters
Raw electricity from the Solar Panels is boosted to a higher voltage of 240V AC so that it will power regular appliances. Solar inverters are the second most expensive component in a solar power system.
1. Local and remote power monitoring.
This will tell you how much power you are generating at any specific time. Advanced logging functions enable you to look at power production over time and see how the weather affects its performance.
2. PC Interface
Connect to your computer
Some inverter are expandable. You should consider one if you think you may want to expand at a later stage. Just plug an expansion pack into the inverter and add some extra solar panels. It’s better that having to install an extra inverter.
4. High Voltage Links and Disconnect Switch.
Cabling is required to connect the inverter to the main fuse box. Although the materials are not so expensive, labour often is. The cable lengths may be very long and you might like to conceal the wires for safety reasons and cosmetic appearance. A disconnect switch is required just in case you need to isolate the solar panels if there is a problem.
CAUTION: there is a specific shutdown procedure that should be followed when disconnecting a solar panels and inverter. Always follow the instructions or get a qualified installer to do it for you. All the voltages in a PV Solar system can be lethal.
5. Fuse-box Connection
Unless you have a very old or small fuse-box, you shouldn’t need to replace it.
Your new system will be linked directly into your existing fuse-box, feeding power directly into the power meter, grid and house wiring.
6. Electricity Meter.
A new electricity meter that can import and export electricity from the grid is required. Your electric energy provider will install this for you.
Warning: Some electricity providers may exploit this opportunity to put you on a ‘time of use’ tariff.
This may mean that you will have to pay different amounts for electricity at different times. This could cost you more or less depending on how you use your appliances. It is possible to actually reduce your bills further. Be sure to shop around.
Off Grid Solar Systems
Providing you don’t mind spending more on equipment, you can definitely go 100% off the grid. A large battery bank is expensive and has a relatively short life cycle but can provide totally independent power.
However there is a downside to being independent. In fact there are three downsides lol.
- Your system will cost 2 to 3 times more.
- Every now and then you will run completely out of electricity.
- Off grid systems require lots of maintenance.
Batteries are a really bad environmental choice as they contain a lot of really nasty chemicals.
3 reasons why off grid might be right for you
1) There is no electricity grid where you live.
2) The nearest grid connection is a long way from your home and it’s too expensive to connect too. A good sized off grid system starts at approx. $25,000 Including G.S.T.
3) You are connected to the grid but experience frequent power outages. You want a system to run when the grid is down.
Choose Your Solar Panels Wisely
There are currently 3 key types of solar Photovoltaic technology available in Australia.
3. Thin Film
Technology Overview – Horses for Courses.
1. Monocrystalline Solar Panels
Being one of the oldest technologies, and more expensive to make, Monocrystalline returns the highest efficiency. Monocrystalline panels can typically achieve 15-20% conversion efficiency. They are made from large sized, single crystals of pure silicon and sliced into wafers. The circular wafers are cut square and used to make a monocrystalline “solar cell”. The silver wires inside channels the electricity that is created when light hits the cell.
A single solar panel is comprised of a matrix of moncrystalline solar cells, laid flat. Monocrystalline solar cells are considered high performance but because they take more space, they perform about the same as polycrystalline.
Some manufacturers make ultra-high performance monocrystalline PV solar modules. These ultra-high performance mono panels return efficiencies of over 20% but cost 30% more than conventional monocrystalline panels.
2. Polycrystalline Solar Panels
Polycrystalline solar panels (Also known as Multicrystalline panels) are also made from silicon. The grade of silicon used is less pure but can be cast into blocks and then sliced into square wafers that are used to make solar cells. Polycrystalline solar cells are similar to monocrystalline in performance and degradation. Because Polycrystalline solar PV panels use slightly more area to absorb available sunlight, the performance return is almost identical to monocrystalline solar panels.
3. Thin Film Solar Panels
To make thin film solar panels, silicon is “sprayed” on to the surface that will used as a solar panel. Usually blue, black or brown, they take less energy to manufacture than the mono or poly crystalline panels for the same rated power.
Although the technology is improving, thin film solar panels are typically only 8-10% efficient and much heavier, so you need a strong frame and strong roof.
Thin Film Solar Panels may degrade by as much as 20% in the first year, before stopping at their specified power output.
How Much Solar Power Do I Need?
When choosing a solar power system the first thing you need to determine is, how much electricity does your household use. Examine your past power bills to calculate your average KW used per month. Then add 20% to cover peak usage.
The size of a solar power system is rated by its “Peak Output” in Kilo Watts based on how much electricity it can produce in an ideal situation, when the sun is at its strongest. Each panel is rated in solar PV peak Watts.
It is important to remember that a 5kW sized solar panel system will only give you 5kW of power for a few hours a day.
And that’s only if it is a clear, sunny day. This is the primary reason that most solar systems are connected to the power grid.
The grid absorbs all the electricity generated by the solar panels that you don’t use while the sun lasts. In turn the grid provides you with electricity when solar production is low or non-existent.
How many solar panels will I need to offset my power usage?
1) Determine how many kWh’s you have used over the past 12 months. The information will be on your bill.
2) Divide your annual kWh’s used by 365 days in the year. This is your average daily usage.
3) Check the list below to see the average number of kWh’s you can expect to be returned per kW of solar panels installed. It varies greatly according to your location.
- Adelaide 4.2 kWh
- Alice Springs 5.0 kWh
- Brisbane 4.2 kWh
- Cairns 4.2 kWh
- Canberra 4.3 kWh
- Darwin 4.4 kWh
- Hobart 3.5 kWh
- Melbourne 3.6 kWh
- Perth 4.4 kWh
- Sydney 3.9 kWh
Choose the city nearest you and divide your average daily kWhs used by its rating.
EG: if your average daily usage is 20 Kwh and you live in Alice Springs, divide 20 by 5 which equals 4.0 Kwh. Therefore I need a 4.0kW sized solar system in Alice Springs to generate the amount of electricity I use each day.
However this may not necessarily be the optimum size from a monetary perspective. Be sure to get good advice from a qualified professional. Talk directly to one of our experts who will explain all the aspects of sizing a system.
AC Solar Panels and Mico-inverters
In the old days, solar panels produced DC (Direct Current) electricity in alignment with the battery charging strategies of the time
To make DC electricity useful, an inverter was used to convert it into Alternating Current (AC) .
The solar panels were connected in series to create higher voltage DC for the purpose of reducing loss.
Consequently this also created problems.
Micro-inverters are miniaturised inverters designed for individual solar panels rather than a series of solar modules. In the 1990’s this technology was considered underdeveloped and unreliable. However over the last few years micro-inverters have reached maturity.
AC Solar Panels
AC solar panels are panels that have been fitted with a micro inverter. It produces Alternating Current (AC) instead of Direct Current (DC).
In Australia most solar panels are still configured with one big inverter and one big DC voltage. This is a major safety concern that could lead to a massive explosion and probably a fire.
However, Solar Solutions are evolving. AC Panels and micro inverters are taking over and high voltage DC systems are being superseded. Micro Inverters help to overcome a number of complexities caused by using traditional solar panels.
Below are some advantages of using AC Solar Panels.
- High Voltage DC systems create a greater risk of high temperature arcing and fire. Micro inverters on each panel convert its output to AC volts, minimising the risk for this to occur.
- High voltage DC systems require expensive breaker switches and fuses. AC switchgear is cheaper and more commonly available.
- Shading just one solar panel connected in a series dramatically affects the entire array. A micro inverter on each solar panel ensures that the output is entirely independent and isolated from each other.
- Due to imperfect manufacturing techniques, each solar panel has a slightly different electrical characteristics and tolerances. Connect together in series; they can cause significant power loss. This phenomenon is referred to as a component “mismatch”. Micro inverters adjust to the individual tolerances of each solar panel, avoiding any potential mismatch.
- Most inverters incorporate some monitoring and fault finding functionality but can only see the combined output from each solar array. A micro inverter monitors each solar panel individually, making it easy to identify problems more quickly and easily.
- Factory fitted inverters save time and money during the onsite system building process. Assembling components in a controlled environment ensure a higher quality product. Many solar panel manufacturers now assemble micro inverters in the factory to produce AC Panels.
- In a series inverter system the entire solar array stops producing power until the fault is fixed. When a micro inverter system develops a fault, the remaining panels will continue to generate power and provide a more redundant proof solution.
- It’s not always easy to add a few more panels to a series string inverter due to the finite maximum number of panels it can support. AC Solar Panels can be added easily because they are modular and operate independently from each other.
- Solar Panel orientation must be uniform when installing a series because they need to produce the same voltage, together, at the same time to feed the inverter. Because of their modular and electrically independent nature, AC solar panels can be facing any direction and not affect the performance of the other solar panels.
The down side of using AC panels and micro inverters.
- AC Solar Panels and the Micro Inverters are both installed on the roof. So if an inverter develops a fault someone has to get up there to do the repair which could add time and cost depending on the design of your system.
- Micro inverters are on the roof and therefore endure greater weather extremes. Mother Nature’s relentless rain, heat, wind and flying debris will shorten the components lifecycle. Beware of cheap knockoffs and inferior designs, they won’t last long in these conditions.
- Series string inverters have a greater capacity to convert electrical power than some micro inverter technologies. However, micro inverters are improving quickly and should compare favourably in the very near future.
- If price is an issue, installing a micro inverter system will add 18-27% more to the total cost of your solar power system.
Are AC Solar Panels and Micro Inverters really a better choice?
There are a number of advantages to using AC solar panels with integrated micro inverters. Most people choose them when they have a shading issue or when they need to adapt to different directional orientations without losing the power they so desperately need.
Other people choose micro inverters because they want to
- Improve site safety
- Avoid a component mismatch,
- Allow for expansion
- Make their system easier to maintain.
- Increase their redundancy proofing.
Micro inverters are personal preference when you can justify the cost for the extra features and advantages they offer.
While the technology is relatively new, approximately 15% of the Australian market is already using micro inverters. PV companies around the world are partnering with micro inverter manufacturers to produce AC solar panels.
Are DC Optimisers a cheaper alternative ?
DC Power optimisers split the traditional string inverter into two basically parts:
Attached to the underside of the solar panel, the optimiser controls “panel level” optimisation in a wide variety of conditions. Many manufacturers now partner with panel manufacturers to factory fit DC optimisers.
By integrating a High voltage DC optimiser (200VDC – 500VDC) with a typical wall mounted inverter, you can combine the benefits of “panel level” optimisation and the cost savings and higher efficiency of a single string inverter.
Micros Inverters vs DC Optimisers
While string inverters are typically higher in efficiency, overall system efficiency is actually higher when using DC Optimizers or Micro Inverters because they both optimise panel output independently. The difference in efficiency between a DC optimiser and a micro inverter is so miniscule that it’s not really worth debating.
DC Optimizers require a single inverter and DC cable protection to avoid potential disaster. Micro inverters however do not and use plug and play connectors instead. As a result they are much easier and faster to install.
However, if your module already has an optimiser fitted and installing a single inverter only plus the cabling, then this option would be slightly faster.
Versatility and Expansion
DC Optimisers are designed to support the “maximum number of panels per string” on a string inverter. Design time takes a little longer. Not all inverters will work with all optimisers, so you will need to study the specifications. There are also some Cool Toys available to help you choose. The total number of DC Optimisers that can be added is capped by the string inverter’s physical limitations making it a less expandable solution.
With Micro inverters, you only need to meet the power output rating of the solar panel. You are therefore only limited by the “AC branch” capacity ie. the maximum power capacity of the AC cables and plug pack system. You won’t reach this limit in an average residential application. A micro inverter system can easily accommodate more panels if you want to add them later. So long as you don’t exceed the AC Branch limits, you can add as many as you need.
DC optimisers have two distinct advantages in larger, commercial installations.
1) Larger string inverters get cheaper as they get bigger.
2) Double optimisers can take inputs from two panels offering greater scale-ability.
Apart from the design and installation perspective, DC optimisers offer a slight advantage in terms of overall cost of manufacturing and production.
Batteries store DC electricity and are cheaper and easier to integrate with DC Optimisers.
Micro inverter systems run on AC, so battery integration is always going to be more expensive due to the cost of additional components.
If you are planning on retrofitting batteries later you’ll need to buy a battery inverter, so it should cost about the same to retrofit batteries to a micro inverter or a DC optimiser.
Having fewer parts on the roof i.e. just the optimiser and not the inverter, sounds logical. However, there is no evidence to suggest that there is any difference in failure rates if you are using quality components. Micro inverter manufacturers are focused on achieving automotive level quality assurance to minimise potential failure.
If a micro inverter system develops a fault, the remaining modules will continue to work. This typology provides a more redundant proof configuration. A DC optimiser based system will completely shut down if a single string inverter fails.
Hypothetically, DC Optimisers seem like the better choice. However, when compared to higher quality micro inverters, the efficiency trade-off is of little consequence.
Furthermore, if you factor in the benefits of improved redundancy one would conclude that micro inverters are the best and ultimate choice.
DC Optimisers can generally failure in two ways; the optimiser or the inverter can malfunction or die completely.
Micro Inverters have a single point of potential failure making it my personal favourite.
Solar panels quality and reliability is also an important factor to consider. PID (Potential Induced Degradation) is a type of systemic failure that occurs in cheaper solar panels. It is caused by high voltages that were applied across the panel during its use and may not show up for as long as 6 to 20 years after its initial installation.
Micro inverters run the panels at a much lower DC voltage. This in theory will reduce the chance of PID developing in the panels. PID is one of the most common medium to long term cause’s solar panel failure.
In the perfect scenario, when everything is perfect, quality products are used and maintenance is regular, High Voltage DC (HV-DC) is robust and very efficient.
Unfortunately we don’t live in a perfect world and perfect conditions are not so common on amn outdoor rooftop and safety has become a growing concern.
HV-DC and 240V AC both present serious electrocution risks but HV-DC is more conducive to creating fires and explosions when conditions turn bad.
DC optimiser manufacturers claim their roof mounted units are able to recognise fault conditions and can isolate individual panels in the event of a major system fault however you still need to use DC isolators which are first most common cause or problems in today’s solar systems.
Please Note: some optimizers require an additional component for the monitoring function to operate, increasing the initial cost of ownership and the chance of system failure.
Cost of Ownership
In the general market, the price of a complete DC optimiser system is cheaper than most micro inverter based systems. However this market trend is changing rapidly because customers want reliability and performance. As the demand for micro inverters increase the overall price will drop, resulting in a lower cost of ownership for all. System reliability and overall life expectancy must also be identified when costing a new solar system.
1) If we base our comparison on the initial installation price only, DC optimisers are cheaper to get started.
2) However, based on a lifetime all repairs and maintenance included, micro inverters are the clear choice.
Can you add batteries to a micro inverter based solar power system?
The answer is YES but you will need to buy a battery inverter
Focus for the Future !