Will installing panels on my roof reduce my cooling requirements? Yes. Research has shown that upto 30% of the electricity costs relating to cooling during summer can be reduced in a given area when solar PV is installed there. This is due to the panels effectively shielding the roof from the sun’s rays and creating an air gap.
Is a Monocrystalline panel better than Polycrystalline? Not necessarily. In the early days of solar mono crystalline cells were made from 1st grade silicon. As such the temperature coefficient (that is how badly it would perform under hot-weather conditions), was better than for polycrystalline. However today this factor is no longer the point of difference. Monocrystalline panels do tend to be more efficient. This means that in the same physical size as a polycrystalline panel, it will produce more energy. However they cost more and so from a kWh/dollar point of view, polycrystalline will often have the edge.
Direct Current (DC) is dangerous so should we use micro inverters? Yes it is true that DC can present dangers not present in Alternating Current (AC). For one the current is continuous and as such is harder to break when flowing (under load) and so the switches required tend to be of different construction. However micro inverters do fail and when installed on difficult-to-access roofs (especially tiled roofs) can present expensive replacement costs in the event of failure. Furthermore the chances of a micro inverter failing are higher than a normal ‘string’ inverter.
Will my car charger use energy for my solar? Only if the charging of the car is happening at the same time as the solar system is producing energy, and the rest of loads in the house still leave enough for the car charging. For example, if at a given point in time the solar system is producing 5kW, and at that instant the loads are 1.2kW, then there is a surplus of 3.8kW. If the car charger is turned on, this 3.8kW of power will be diverted to the car charging station (rather than being exported) and only if in excess of the car charging requirements will export happen. If the car charger needs more power than that provided by the solar, it will automatically draw that from the grid.