Switch to DC?

With solar poised to play a big role in renewable energy offerings, is it time to switch our homes and workplaces to DC? Or is it not advisable?

The electricity that comes out of a photovoltaic panel is DC and hence a part of every PV solar installation is the installing of a big inverter to change the DC to Ac.

A company is exploring the idea of having many small inverters (aptly named microinverters) into each solar cell or module instead of one single, large inverter. Startup GreenRay Solar is getting funding to develop this kind of technology, so that one day a homeowner can buy a solar panel and pretty much install it him/herself. Its panels will be simple to install because they bypass the inverter step.

Yes, these solar panels will cost more money. But, microinverters offer additional benefits. For example, if part of the panel is blocked, it will not affect the other parts. And, if you are the kind of person who wants to carefully monitor your system’s performance, the microinverter panels will give you more precise and detailed information.

But, most AC/DC converters are designed for a specific load (power usage) at which they are most efficient. In this regard, larger converters will be more efficient than many tiny micro converters. Right?

The technology to convert power from AC to DC, ramp up the voltage, and crank it all back down to usable voltage AC was so wasteful some time ago which was why DC transmission was avoided. But now the up/DC/down/AC process wastes less than 2% of the energy and even that is recovered in more efficient transmission at distances greater than 250 miles or so. A major HVDC line is the Pacific Intertie which carries hydro power from the Pacific Northwest to Southern California. It may soon be used to move thermal solar to major western cities.

But if you are living off the grid, does it make sense to convert all your equipment into DC friendly gadgets? Inverters are cheaper to buy.

With more digital technology in the market which requires DC power, is it wiser to adopt DC? Direct access to DC is believed to be safer and more efficient. And more sustainable, reducing the amount of materials needed. More and more digital, DC-powered devices today operate at less than optimal efficiency in an aging, AC-based building infrastructure.

Would total conversion not mean huge costs? Should we go for parallel lines of both? Most AC/DC converters are designed for a specific load (power usage) at which they are most efficient. With loads most often below, efficiency is lowered.

One of the other issues with low voltage DC on a household level is interruptabillity. When a DC current is suddenly interrupted, the current will want to keep on flowing due to inductances in the current loop present. Large capacitance or charge will be available in such a system. In comparison, AC power goes to a zero voltage level 5060 times per second.

Is the AC-DC part the problem or the lack of standardisation of secondary equipment – like the many adaptors for mobile phones, ipods, laptops??

Join in the discussion. Here is a ‘direct’ chance!