Most of us are aware that solar tracking systems produce more energy per kW of solar installed but the question often asked is this a more viable option than a static system?
In this presentation we will look at the different tracking systems from a large ground mount system perspective, how much increased production wise over static systems, cost of systems, cost of maintenance, and other factors.
A solar tracking system maximizes production by orienting the panels to follow the sun during the day.
Solar trackers are typically used for ground-mounted solar panels and tend not to be used in domestic situations.
The angle at which the sun’s rays hit the solar panel (known as the “angle of incidence”) determines how well the panel can convert the incoming light into electricity and the narrower the angle of incidence, the more energy a photovoltaic panel can potentially produce.
Solar trackers orient panels so that the solar resource strikes them perpendicular to their surface.
A single-axis tracker moves your panels on one axis of movement. These configurations allow your panels to arc from east to west and track the sun as it rises and sets.
A dual-axis tracker allows your panels to move on two axes, aligned both north-south and an east-west. It can track seasonal variations in the height of the sun in addition to normal daily motion.
Most tracking systems out there are active which means that the tracking system is motor driven, to energise a mechanical device that tilts the attached solar panels the right way.
Passive solar trackers also track the solar rays but they move by using the heat from the sun to warm a gas which expands causing a mechanical movement of the solar panels. When the sun moves and the gas cools, it compresses again and the panels move back.
Generally, a solar panel system with a single-axis solar tracker installed sees a performance gain of anywhere between 10 to 30 percent and in the right situation, a dual axis tracker can produce up to 40% more than a static array.
But at what cost? Systems that incorporate a tracking configuration:
When analysing the cost effectiveness of any particular system will need the appropriate tools and assumptions have to be made.
So we are talking ground mount systems here, off course, and some of the assumptions are as follows:
Some more assumptions:
A 1.28 MW system @25.5 degrees North facing in Melbourne Australia will produce:
So a lot of the assumptions are the same as the static system but some aren’t:
Now let’s assume that the increase over a static system is 25% and:
A 1.28 MW system with East West tracking:
So the tracker system is the more economically feasible based on the assumptions made. We have assumed a price to install of $1.20/watt and one question to ask is at what price does the static system become more attractive?
I have used goal seek, part of the What If analysis in Excel and the answer to that question is:
a little over $1.25/watt
Also that question can be asked in reverse. How much does the $/watt price have to drop before the static system becomes more viable than the tracker system?
The answer is $0.95/watt. Both calculations were based on the IRR for a 10 year investment.
I have assumed a % increase over the static system of 25% but what if we use, for example, another lower %?
Let’s assume a 20% increase.
How does this affect our overall single tracker performance?
Let’s now assume a 10% increase.
How does this affect our overall single tracker performance?
For all examples given I have assumed a 50:50 split in regards to negating draw from and export to the grid. Now with a tracking system the output curve tends to be a lot flatter which in a lot of cases more closely matches the consumption load profile of a lot of sites.
So what happens when the split goes to 70:30 in favour of direct consumption?
When comparing to ascertain what is the best system, static versus tracking many assumptions need to be made in addition to the reality of actual energy production and how it matches with site loads etc.
The reality is that a tracking system of the same capacity compared to a static configuration will produce more energy at any point in time but at what cost? I have given examples ranging from $0.95/watt to $1.25/watt. When talking of IRR in these examples I have selected 10 years but if another figure was selected this would alter these results.
In addition if the cost of the land was factored into the calculations, the results would be different again.
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