TechMark Global

The automobile is not the only personal space we occupy increasing in its electronics content. Indeed, significant growth in digital control is also seen in our homes, at least in the Americas. In addition to the traditional audio,video and internet applications, electronics are increasingly linked to our energy efficiency efforts. Primary home functions digitally controlled or monitored include lighting, HVAC, security and lighting. Various secondary functions, not necessarily energy-focused, are also being digitized.

Up to now, growth has been hindered by lack of interoperability and user-friendliness. Wireless solutions are now appearing that promise a path forward on both these fronts. Although standards are still required, wireless technology reduces installation costs (by reducing running of wires in the walls), provides flexibility and do-it-yourself capabilities, and enables central control through standard TCP/IP and 3G networks. Finally, the advent of low cost computers, home network gear, and powerful hand-held devices provide the home owner the power to control the digital home with one interface...remotely.

Restricted to techies up to now, it now appears that the drive to reduce our collective carbon footprint is getting the environmentally conscious on-board as well. The government is also helping with stimulus packages and subsidies. The convergence of these forces will finally bring the digital revolution...well...home.

In this first article, focus will be on residential solar systems, categorized as being thermal-based or photovoltaic. A brief discussion on each approach is given.

THERMAL SOLAR

As the name implies, such systems are based on the heating of a transfer fluid circulating through a collector. In its simplest incarnations, the transfer fluid is the liquid of interest, such as in a pool heating application, but most of the time the energy is used to heat a water tank (hot water system). Another layer can also be added whereby the hot water is used as part of a hydronic heating systems. In most cases, the system is comprised of: a collector, installation fixtures, a hot water reservoir, a recirculating pump and an electronic control (the pump is omitted in static collectors).

Collectors: Comprised of pipes transporting transfer fluid through copper piping, at atmospheric pressure or under vacuum. Collectors are at the core of the system and suppliers such as Bosch, Viessmann, Rittersolar, UMA Solar, Rheem, Solar Hot, SunEarth, Velux and Sunda tend to offer complete solar hot water systems.

Hot Water Tanks: Various configurations exist but they have all one thing in common...a backup to heat water with a conventional source of energy. In some systems, a standard hot water heater is combined with a solar heated reservoir. In other cases, the backup coil system is integrated in the same tank.

Controls:  Electronic controllers for thermal solar installations are akin to thermostats but differ in its use of a differential temperature approach. The delta between the temperature of the collector and that of the tank water drives the recirculation of the heating fluid. Resol and Steca dominate as electronic suppliers. Tekmar and Enerworks, canadian companies, have recently introduced control units.

Distributors & Contractors

Companies like Caleffi, groSolar and Solar Direct integrate solutions at both the system and sub-system level.

A thermal solar hot water costs are in the 10 - 15K range. Payback is in the 10 to 15 year range. Government tax credits improves these numbers slightly.

PHOTOVOLTAIC (PV)

In a photovoltaic system, the sun's radiant energy is directly transformed into electricity through the PV cells. The electrical energy is either stored in batteries or channeled back to the grid. Government incentive programs tend to favor PV installations by offering a buy-back of the energy sent to the grid. Such installations are called Grid-Tie systems for obvious reasons.

PV offerings consist of a collector cell or module, a AC-DC inverter, possibly a battery backup and some fixturing. Although distributors and integrators will piece a system together, suppliers tend to specialize at the sub-system level.

Cells/Modules: Kyocera, Sanyo, Evergreen Solar, Mitsubishi, Suntech, Schuco,

Factory automation for the latter: Applied Materials, DEK, BTU, Siemens, Kuka, Rexroth Bosch group, Siemens, Rena

DC-AC Inverters: Outback Power, Fronius, Terrawatt Power,Zanthrex and Solectria Renewables.

The cost of a PV system is in the 20K range and the payback is therefore more in the 15-20 years. Government incentive programs and tax credits improve the payback significantly.

Data Management:

Whatever the choice of solar systems, users are demanding data management capabilities. They want to track energy savings and they want the data captured and managed by the home server. This is the same server that controls the lighting, the HVAC controls and the irrigation and so energy production is linked back into the digital home at a systemic level.

Our homes are not only going digital, they are going green digital!