, I wanna use only rtc, linear actuator and arduino board for the project.
Unless you really want to calc the sun's position, as suggested below, track the sun.I would think that 4 LDRs would be cheaper than a RTC, the code smaller and as pointed out, accuracy is of no concern, it just tracks. Simpler still if you use a N/S mount as you only need 2 LDRs, and your single actuator. "darkness" is used to reset to the morning sun.IDK, but tracking may also provide more power from reflected light in times of cloud cover as the sensor, being a heliotrope would point to the brightest part of the sky, not where it thinks the sun is.in fact, at Nick Gammon pointed out, you don't need a constant sun location if using a simple N/S mount and single actuator! All you need is (usable) sunrise and day length (1 byte would do, since you will not get 15hrs of usable sun) You may also have mountain/hill/building shadow to contend with . You may also need to adjust for apparent sun speed. You then move your actuator, starting at the correct time, at the correct speed for any day. Personally LDRs would be my choice - simples![/edit]
For LDR it require periodic maintenance.
Sorry AMPS-N, couldn't help myself You have painted yourself into a corner, it will have to be calculated then, but you will have to compromise on "cheapest". Leap years can be handled with a counter, but you will need to keep at least some variables in NVM.keep us posted.
whole idea is i wanna do with cheaper solution , I wanna use only rtc, linear actuator and arduino board for the project.If i am using above component is it possible to it??if yes how can i do it??how can calculate sun elevation angle??i don't have any sensor to locate and control the position.
How accurately are we trying to track the sun's position? Some of the solutions being discussed seem to be aimed at very high accuracy indeed - which might be justified if we're trying to aim a telescope but would be ridiculously over the top if we're just trying to point a solar panel in the right general direction.