The larger your Photovoltaic Solar Energy System is, the more efficient it will be. Whilst solar panels that are fitted on top of your existing roof is less costly that using solar energy roof tiles, the cosmetic appeal is more desirable.
If a system produces lots of energy, then the return on that energy is greater than that of a smaller system – so the more that the system costs, the more energy you can save;
Overall, whatever the size of your system, in time you will gain back the initial investment. Benefiting from a small tax-free income from selling back your electricity to the government (see also Feed in Tariff).