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

What is the Future of Solar Roof Technology? – Part 2

(Left to right) Rob Fleming; Dennis Wilde; Alain Garnier; Mark Stancroff; Jeff Wolfe

As I discussed in the previous Blog, CertainTeed hosted a luncheon and panel discussion at the 2010 Greenbuild Conference and Expo on The Future of Solar Roof Technology.

Jeff Wolfe, co-founder and CEO of groSolar, represented one of the largest installers of residential solar products in the U.S.  Jeff discussed the fact that the rate of adoption of solar in the U.S. is slow but there will come a time when integrated photovoltaics will be the standard.  

The first hurdle is integrating two elements: a roof and electricity. It’s hard enough to install a roof so it doesn’t leak. Now toss PV into the mix and the new assembly requires additional skills, tools, and knowledge. One key to successful applications going forward is to design integrated systems which simplify installation and maintenance.

The next challenge is the question of who are solar roof installers? Are they roofers, electricians, glazers (remember, some systems have a lot of glass in them)? And what department do you go to in City Hall to obtain the permits? Is it a roof or is it electrical? As a country, building codes and processes vary greatly from state to state and having to battle your way through the local building code department for each new application will dissuade roofers and consumers to take on this new technology.

Alain Garnier, Saint-Gobain Solar mentioned that the solar industry is growing by about 40 percent in other parts of the world.  That could be largely due to the energy costs.  Our “cheap energy” has been a hindrance to consumer demand in this arena. As an example; Europe is far ahead of the U.S. with regard to energy efficiency and passive house adoption largely because the economic case was clear.

The expediting of solar adoption in the U.S will most likely be determined by two things; first, energy rate increases that will cause pain to consumers and, two, federal and state incentives that encourage and reward consumers for taking a significant step toward more efficient buildings.

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

What is the Future of Solar Roof Technology – Part 1

(Left to right) Rob Fleming; Dennis Wilde; Alain Garnier; Mark Stancroff; Jeff Wolfe

At Greenbuild, CertainTeed sponsored a luncheon and panel discussion on The Future of Solar Roof Technology.  The panel was very diverse, representing manufacturers of solar materials and end users. The panel included Dennis Wilde, Principal and Development Advisor, Gerding Edlen Development;  Alain Garnier, General Manager, Saint-Gobain Solar U.S.;  Jeff Wolfe, Co-founder and CEO of groSolar; and Mark Stancroff, Business Manager, CertainTeed Solar.  Because of the amount of good information discussed at the event, I am breaking it down into more than one Blog.

The event was moderated by Rob Fleming and Chris Pastore from Philadelphia University who are also known as Ecoman and the Skeptic on their Philadelphia radio show. Rob is an architect by trade and Chris is an engineer.  Both are professors and on the faculty at Philadelphia University. They represented the real world, both the advocates and the skeptics, and created a perfect atmosphere for the audience by challenging the panel and encouraging the audience to do the same, which they did.

The audience was a mix of users and makers as well so the discussion was very robust.  I find when I travel to talk to groups about sustainability this is exactly what you find – skeptics and believers.

According to the end users on the panel, Jeff Wolfe and Dennis Wilde, the adoption of solar and photovoltaics in the U.S. continues to be slow.  Consumers are skeptical and are concerned about the return on investment.  They are waiting for their neighbors to invest.  Homeowner associations are also challenging this initiative based on aesthetics.

Dennis Wilde has been involved in building with photovoltaics and his firm supports initiatives like the Living Building Initiative. He had some interesting insights into the benefits of photovoltaics compared to integrated wind technology.  Referring to a specific project, Dennis stated that the return for solar will be three to five years on that project and the return on the integrated wind technology will be about 104 years.  It is clear that integrated wind technology will not give the return as quickly on that project but it still has merit as a renewable energy source. The issue may be one of a matter of scale. Dennis also discussed the success they are having using photovoltaics on the façade of the building as opposed to the roof.  With Living Building, you have to maximize the power generation to meet the benchmarks and they have seen success with this technique.

Stay tuned for more on The Future of Solar Roof Technology.

I would love to hear your thoughts if you are using photovoltaics in the field. 

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation