Financial analysis

comparable factors

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.

Calculation methods widespread in marketing materials include:

Investment cost / Nominal panel power

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.

Possible ways to install PV sets.

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.

of costs

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.

Let's compare the cost of different installations, with actual efficiency comparable to a set installed on permanent ground stands with a nominal power of 10kW;

  • fixed ground set

    - as reference.

  • fixed roofing set

    - mounted on 2 roofs slops
    south-east and south-west.

  • Set based on
    Smart Solar Trackers.
fixed ground set

Set based on fixed stands will consist of:

  • 34 pcs of photovoltaic panels with power 300W
    3 400 USD
  • 1 on-grid Inverter
    2 000 USD
  • Fixed rack construction with foundations
    2 700 USD
  • Wiring and security DC
    1 000 USD

TOTAL: 9 100 USD

AREA: min 80 M2

fixed roofing set

Set installed on 2 roof slopes will consist of:

  • 40 pcs of photovoltaic panels with power 300W
    4 000 USD
  • 2 pcs of on-grid Inverters
    3 200 USD
  • Construction / mounting profiles
    1 000 USD
  • Wiring and security DC
    1 000 USD

TOTAL: 9 200 USD

AREA: min 70 M2 (roof)

Rei Solar Tracker

Based on Smart Solar Trackers set will consist of:

  • 24 pcs of photovoltaic panels with power 300W
    2 400 USD
  • 1 on-grid Inverter
    1 200 USD
  • 2 smart tracker racks
    3 000 USD
  • Wiring and security DC
    400 USD

TOTAL: 7 000 USD

AREA: min 100 M2

Be aware of three important facts:

  • to get similar annual performance of the roof set compared to the reference one, necessary is to use a larger number of panels due to unfavorable working conditions (temperature, setting, 2 separate surfaces, wiring) and two inverters instead of one due to splitting MPP of 2 directions of panels. (However, there is important advantage of a roof installation - saving space on the plot.)
  • to a smaller number of panels mounted on the follower rack you need a cheaper by 50 % infrastructure in relation to the reference installation.
  • As far as the issue of savings on the purchase of solar panels is obvious, the savings resulting from the use of a smaller or less inverters are often neglected. The smaller total length of DC cables reduces the own losses of the installation not only the costs.

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.


For most users, the tracker is a solution that actually increases the return on investment due to the ability to maintain reasonable set power for a significant part of the day.

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.

Alternative calculation - pessimistic variant.

Fixed number of panels (20 pieces x 300Wp), the same inverter and protections. Smart Solar Tracker costs about 5% more                      than fixed-ground installation and about 10% more than roof installation. So how long will we wait for tracking system investment pay back?

  • Roof installation total cost
    6 500 USD
  • Ground installation - fixed total cost
    7000 USD
  • Installation based on the Smart Solar Tracker
    7 300 USD

Difference Roof vs Tracker: 800 USD

Difference Ground vs Tracker: 300 USD

Return on investment in Smart Solar Tracker.

Price of electricity for a household in the US ~ 0.15 USD / kWh                  Calculation based on annual performance data from an independent source.

  • Roof installation - annual production 5 900 kWh
    Value: 885 USD
  • Ground installation - permanent - annual production 6 300 kWh
    Value: 945 USD
  • Installation based on the Smart Solar Tracker stand - annual production 8 500 kWh
    Value: 1 275 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

Fundamental question is: If the Solar Tracker service costs are significantly bigger?

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..