I want to focus solar energy on a solar cell with the use of mirrors (that I already have) and maybe some aluminum foil.
Should I not go overboard on the focusing? How can I detect if the focused solar is too much?
Background information: I live at 45° latitude, the sun is not that strong here.
Yes, if the photovoltaics aren't designed for operating as concentrated PV, it can shorten the life of the cell: the additional thermal stress can be huge; the cell will operate at a higher temperature, as it can't dissipate heat that quickly. This can crack the encapsulant, leading to moisture ingress and the corroding of the cell and/or its contacts.
Higher operating temperatures also reduce the efficiency of the cell during the period of raised temperatures. The panel's datasheet will normally have a coefficient for this: the rate at which efficiency or peak power drops off per degree change in temperature.
You'd have to find positions for your reflectors that would adequately bounce sun off onto the panel, without shading the panel - that might not be easy, particularly at your latitude, where the position of the sun in the sky can vary a lot over the year. And the maintenance and wind-loading on the reflectors should be taken into consideration.
Solar panels have become so cheap now, that concentrating the sun is rarely worth it.
Even at 45° latitude, there will be periods of hours of intense sunlight. If I were to try the reflectors, I'd put a temperature sensor on it (it may already have one), and get an idea of normal cell rear-surface temperatures at 3 or 4 continuous hours of peak summer sun without the reflectors; then I'd keep an eye on that temperature when operating with reflectors over the same sort of exposure period.
This is an intriguing question. While the idea of using mirrors or other reflective surfaces to focus sunlight onto a solar panel might seem like a good way to increase output, there are several factors to consider.
Excessive heat from concentrated sunlight can cause thermal stress on the solar cells, potentially leading to faster degradation or even damage. This is especially true if the solar cells are not designed to handle concentrated photovoltaic systems.
Moreover, the angle of incidence of the sunlight plays a crucial role in the effectiveness of this method. Adjusting the position of the mirrors or the solar panel throughout the day and year to maximize efficiency could add complexity to the system.
Given the decreasing costs of solar panels, it might be more cost-effective and simpler to increase your solar output by adding more panels if you have the space. If space is a constraint and you wish to experiment with focusing sunlight, it's important to do thorough research and possibly consult with a solar energy expert.
