Solar trackers are deployed to orient the solar panels towards the sun. These devices change their positions many times in a day to take the sun rays head on. The primary objective of Solar Trackers is to improve efficiency by minimizing angle of incidence between sun rays and solar photo voltaic panels. Solar trackers are either single axis or dual axes types, depending upon their movement.
Typically a concentrated photo voltaic or a concentrated solar thermal will mandatorily have the solar trackers or otherwise they will not able to function. The passive solar tracker uses fluids with specific gravity in narrow band to position themselves appropriately so as to have angle of incidence, close to zero. But the passive trackers are rarely accurate and their technology needs further improvement. The other trackers are motorized and they position themselves with the help of either light sensors or the weather files data. The positioning of solar trackers can be done manually for a smaller system or through motorized gear unit which positions itself based on inputs from sensors and weather data file of that location. We have compared here the solar output from fixed as well as dual axes solar tracked array. The efficiency gain is about 23% for a location in New Delhi.
The debate on use of solar tracker has been going on for more than 5 years now. The cost of solar tracker equipped solar panel dual axes array is about 50% more than the fixed array. The efficiency gain is about 25-30% when the dual axes solar tracker array is used in place of fixed array.
The advantage that a solar tracked array has over the fixed array in terms of efficiency gets nullified when one compares the additional cost involved in procurement, installation, operation and maintenance. At higher altitudes the movement of sun varies significantly therefore the single axis or the dual axes trackers are found to be more useful there.
Some solar developers never ever deploys movable arrays due to concern on long terms O&M expenses. Rather they increase the number of panels to have more output. With falling solar photo voltaic module prices, they find this option much cheaper. Before deciding to go for solar trackers one has to go deep and work out proper economics.
Fixed Array or Solar Tracker Array
The big question here is what all goes in to taking a decision on solar array arrangement. For any decision to opt for the solar tracker array there are two things we have to see:
- Efficiency improvement
- Cost involved – Initial as well as running O&M
- Land acquisition cost
The cost economics has to work out in a way that the decision to go for fixed or movable array should be justified. Paying a price for movable array which is 60% more than the price of fixed array to have efficiency improvement of 40% is not at all justified. The O&M expenses of such movable panels would be additional and over and above the initial cost. Rather,in such cases it would be better to go in for more number of panels to improve the output.
Land acquisition cost also has a bearing on the decision to select solar trackers. Roof top systems are generally fixed type or at best single axis types as the tracker systems put additional weight on the roofs which is not desirable.
In the end, I would only say that both the systems have their advantages. Before you decide, its better to work out the initial as well as long term cost perspective vis-a-vis efficiency gain before taking a decision.