Errors

When you examine the misalignment of the system considering the tracking of the sun the most critical aspects to be examined are the angular misalignment and the acceptance angle of the collector.
The misalignment is simulated by rotating rigidly the collector around the axis containing the vertices of the paraboloids.

As it can be seen from the figure below, for a counter-clockwise rotation the light mostly hits the right side of the tube.

For thermal applications are acceptable all mismatches that still allow to hit the target.
In the example shown in the figure the maximum acceptable angle is 1.1 °.

In single-axis systems, as may be the linear parabolic collectors, there are two types of alignment: with the x-axis along the north-south direction or with the x-axis along the east-west direction.

In the first case the purpose of the tracking system is to compensate the hourly variations of the position of the sun, while in the second case the seasonal variations are compensated in order to be perfectly aligned at noon.
The analysed systems normally have an orientation north-south. In this case the effect of a misalignment of the X-axis from the expected direction causes different results depending on which the absorber is integral with the mirror or not, as can be seen from the figures below.

A

B

Figure A shows the absorber view, maintained in the correct direction north-south, illuminated by a paraboloid with instead has the X-axis tilted of 1 ° with respect to the same north-south direction, calculated in December, for the latitude of Florence.
Figure B instead shows the view of the absorber rotated in solidarity with the paraboloid of an angle 0.5 ° with respect to the north-south direction, always in December and for the latitude of Florence.