As installers of PV modules, we try to find a solution that works well, for a long time and, perhaps most importantly, ensures a quick return on investment costs. To help in making decisions, we analyzed the financial data of installations in fixed systems and alternative assembly systems on dedicated racks following solar energy. The results allowed us to present a proven calculation that may be useful when analyzing the profitability of specific solutions.
The comparison of installation costs, whether it is a roofing system or a ground or active tracking system, usually comes down to a simple collation of intuitively defined costs and laboratory measured performance. We do not bother to verify both parameters in the reality in which our installation will operate.
It is a coefficient based on the lab power of panels and the optimism of traders and strongly falsifies the final financial effect of the investment. The USD / W type coefficient can be used to compare the purchase costs of the panels themselves or, at most, the inverter + panels, but this is not the only element of the installation.
The investor expects a real reduction in the amount of energy purchased from network providers. The measure of the supplied power is kWh and not W, so such calculations do not serve anything. There is a problem - how to convert the nominal power of a photovoltaic installation into really supplied power. Due to the location and other parameters set will not obtain nominal power of PV panels.
There are theories that permanent assembly of a PV set can be a good solution due to geographical and location restrictions, such as soil type and terrain. This can be true for column structures that require solid foundations. Pay special attention to this fact when choosing the type of stands.
Living in zones around the tropics or consuming very little electricity per month, fixed systems can generate enough energy from roof installations. Such a solution, after fulfilling certain conditions, reduces the expenditures for construction elements by 60%, also saves space on the plot.
The disadvantage is often the wrong orientation of the panels. The possibilities of adjusting the position of the modules are limited by the roof structure. This case, may be over-invested by building an atypical and expensive superstructure on the roof. Apart from esthetic issues, errors at this stage can be catastrophic. In case of strong wind, our installation will be broken together with the part of the roof slope.
In most households, a roof installation with satisfactory power will not fit on one roof slope, or it is not possible to fit it only on the roof, which forces the investor to build additional ground stands. This is the most brilliant case of overinvestment in relation to the Smart Tracker installation due to the poor annual efficiency of roof PVs, separate inverters for each roof pitch and much wider cabling and security elements.
An investor with land space can be used to build a farm. Mostly such free spaces are located in places where the direction of insolation is not regular during the year. There are also places where ambient temperatures significantly affect the efficiency of PV modules. It is difficult to estimate the annual operating time of the set (in hours) with satisfactory power of the fixed fixing system. The erroneous design of the foundation direction of the set is felt throughout the entire lifetime. Adjusting the settings to maximize the efficiency of energy production is later very expensive.
At the investment stage, we can’t assume that on the following 5 years will be only sunny days. We can’t know what the actual production will be. However, we know with great accuracy for a given time at what angle the sun's rays will fall in every place on earth. What's more, we have a fairly well-measured energy intensity of solar radiation, so-called irradiance. Based on these data and the actual performance measured, we can conclude that a fixed installation, unable to adapt to the changing position of the sun on the horizon, produces at least 40% less energy expressed in kWh than the set installed on solar trackers.
- as reference.
- mounted on 2 roofs slops
south-east and south-west.
TOTAL: 9 100 USD
AREA: min 80 M2
TOTAL: 9 200 USD
AREA: min 70 M2 (roof)
TOTAL: 7 000 USD
AREA: min 100 M2
The price of the rack itself is probably surprising. why Smart Tracker costs the same as a fixed construction?
The main reason lies in the price of steel. The weight of profiles needed to build a solar tracker is comparable to the amount of steel intended for a fixed construction. Poor fixings need additional foundations and construction documentation untied on the plot.
Although intuitively, the construction of a rigid structure is simpler, the same competences are needed for both installations, so the cost of labor is similar.
Summing up the whole calculation, the use of Smart Tracker saves over 20% of financial resources for investments in solar farms with the same annual capacity.
Trackers are available both as one- and two axis. There are some key differences between them.
One axis tracker, tilt in the Y axis (allowing them to capture slightly more sun than traditional stationary systems). This solution does not work in regions with latitude greater than 40 degrees on both the north and south sides. We did not take them into account during the calculation because their costs are much higher and the increase in efficiency does not allow to reduce the number of panels in the entire system so dramatically.
Two axis trackers, tilt in the X and Y axes. They are able to handle any amplitude of the angle of sunlight are more technically sophisticated construction and give much better results.
So, while static systems reach maximum power for several hours in the middle of the day, tracking devices can maintain this performance for much longer. Following the sun from dawn to dusk, the two-axis tracker can make better use of the potential of the sun's rays. We have successfully recorded up to 50% more energy produced in relation to the roof installation.
Moreover, if an investor lives in a region providing access to network meters, he can actually earn on his installation by introducing surplus energy into the network and compensating the monthly bills for electricity.
Difference Roof vs Tracker: 800 USD
Difference Ground vs Tracker: 300 USD
Difference Roof vs Tracker: 390 USD Return on investment in tracker 2 years
Difference Ground vs Tracker: 330 USD Return on investment in tracker 1 year
Service work is required regardless of the method of assembly. Roof installations during the inspection require more time to organize the tools and to move more carefully at a certain height. Fixed ground installations have a larger cabling system, panels and a larger inverter. Active systems have movable elements and drives in exchange for fewer panels and easy access to them.
Remember that dirty panels are a decrease in performance and depending on the environment, it is required to clean them 2 to 4 times a year.
Fixed installation left alone, after one year of production, produces an average of 5% less energy due to dirt and streaks on the surface of the panels. During cleaning and review, it is not a great effort to review of moving parts and control measurements. Static load and slow operation of active stands do not destroy well-designed moving elements so fast. The main threat to the smooth operation of the set is corrosion. Therefore, service activities are limited to verifying the condition of the covers, cleaning and lubricating several points. Information about higher costs of the Solar Tracker service results from the lack of awareness of how dirt affects the performance of the panels and what is the cost of cleaning the set placed on the roof..