Thomas Alva Edison discovered electricity in 18th century and it was used by people in their homes in the form of DC electricity. However over the period electricity was to be transported on longer distances, due to development centralized power generating stations and the need of AC electricity was realized as the electricity transmission through AC as it is more efficient and economical. While solar is reaching to grid parity, it is accepted that home owners will find it affordable and much more reliable source of electricity and rather than using AC electricity in their homes, rather they will be using DC electricity. Most of the house hold appliance such as Electric lights, Fans, Refrigerators, Music system and air-conditioners are now available in market to run on DC electricity. While we are using AC electricity about 20% of electricity is wasted in house hold inverters itself due to conversion from DC to AC from battery bank.
If we have solar PV in rooftop system which is producing DC electricity, then why there is need to converting it to AC and then back to DC to run your electronic and other appliances which primarily require DC electricity. While most of our house hold appliances can run on DC electricity the new homes which are considering solar as integral part of their roof top generation can have DC wiring circuit in their home and can run their all there appliances on DC. May be in future the house hold will have both DC and AC circuits in their home in order to maximize solar energy utilization from their rooftop. Many of the large Data centers use DC electricity which they convert from AC electricity, it is expected some of these data centers will shift to solar PV and reduce their AC to DC conversion losses which are of the order of 15-20%. In US many universities and hospitals are experimenting with DC has their primary energy circuit and AC poor circuit is considered as backup in case of non-availability of DC power. Here are the few examples already available in the market DC based appliance.