A Case for the Return to DC Power

Lucas Hamilton

As we have seen many times, tides change and we return to previous processes because they are actually more efficient.  So why shouldn’t this be true of electric current?

If we look at onsite power generation for buildings like photovoltaics (PV) we see that they are generating Direct Current (DC). In order to move toward more sustainable solutions like photovoltaics there will need to be a return to Direct Current (DC) for our power.

We are seeing a resurgence of DC into our lives through items like lighting, with the switch to LEDs, and computers. These are two of the biggest power consumers in our commercial buildings and they run on DC.  When we convert Alternating Current (AC) to DC power 20 percent of the power is lost in that transference.  Feel the heat coming off your computer power plug. That heat is energy loss. Now imagine you have a building with PV on the exterior generating a fixed amount of DC current. If you invert the DC to AC in order to put it into the grid (-20 percent) and then plug your computer power cord into an outlet to get that power back, you loose 20 percent again. With the technological limitations we have with PV efficiencies, limited surfaces upon which to install the cells, and ever increasing demands for power within our buildings, how can we afford to keep loosing power to these inversions?

It is time to reevaluate DC in our lives! As we move toward more renewable energy, like photovoltaics (and they will play a larger part in our lives moving forward) we should consider how many of the appliances we use could be run on DC.  At the same time, if you are planning a new home or building and will be employing photovoltaics, consider keeping more DC current available throughout the building. Keeping things that are DC as DC and not plugging them to AC circuits makes sense.  Maybe it’s time for a second plug in the room.  A DC plug.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation