This is the cenario. Your yearly energy use comes by mail and it states that the total amount of energy used your household is 7000kWh.Then you make the decision of switching to get solar panels. The question is what area should your solar panel be given that the average annual length of daylight is 2.0.
It is not that simple. There are 3 main types of solar cells. Monocrystalline silicon is the most efficient and produces the smallest solar cells, and therefore the smallest panels. Poly-crystalline (or multi-crystalline) silicon produces the next most efficient type of cells and are a popular choice. Amorphous (or thin-film) silicon uses the least amount of silicon and also produces the least efficient solar cells. This means thin film system take up more area than the other two; an important factor to consider in relation to possible future upgrades; i.e. if you'll have enough space left to do so. The North (in the Southern hemisphere) or South (in the Northern hemisphere) facing roof collects the most energy. So this biases the roof area required. Your energy usage can be changed. Hot water (a major energy user) could be better using direct solar heating with peak demand boosting, either from mains or solar. There are other possibilities, either to reduce demand or to provide energy from other sources. Not all sunshine hours are equal. Hours around midday are far more productive than hours later in the day. This must be factored in.
