Bringing solar power home

Published Tuesday, May 12, 2015 in the New Brunswick Telegraph Journal and the Fredericton Daily Gleaner.

If you’ve long dreamt of lowering your carbon footprint and becoming energy self-sufficient, here’s some great news: the technology and economics of solar power systems are getting better every day.  

Here’s a quick overview of grid-tied solar power systems: components, costs, payback and pitfalls.

Components

Solar power systems consist of three main components: panels; mounting systems; and inverters.

Panels, the visible part of solar systems, have been the focus of much research and development in recent years.  As a result, they now cost a fifth of what they cost just five years ago.  The most common size is 250 watts, about one meter wide by 1.5 meters long.  Solar arrays can include as few or as many panels as desired.  Panels typically carry 25 year warranties.

Panels can be mounted on the ground, on poles or on rooftops.  Rooftop installations are most discreet.  Ideally, roofs should be south-facing, steeply pitched and shade-free. 

Inverters are electronic devices that take the power generated by panels (low voltage direct current) and convert it into grid-compatible power (120 volts, alternating current).  Solar systems can have a single large inverter (the disadvantage being that the entire system goes down if it fails) or a small inverter for each panel (the advantage being that failure of an inverter affects only one panel).  Systems with the latter option are most easily expandable. 

Sizing 

In New Brunswick, you can produce whatever power it takes to lower your annual bill to zero.  The ‘annual’ part is important: it means you can feed a surplus into the grid during the bright days of summer and then draw down that surplus during the dark days of winter.  However, you won’t get credit or compensation if you feed more into the grid than you use on an annualized basis (and accounts are reset every March 31).

The number of panels required by a home depends on how many kilowatt-hours are consumed annually, as indicated on a power bill.  A qualified installer can review your bill and tell you what size system you need.  Efficient homes may be able to achieve energy-neutrality with a 5-8 kilowatt system; the average home would more likely need a 10-12 kilowatt system.  An array that size would cover most of a typical roof.

Costs and payback

Complete grid-tied solar systems – panels, mounting systems and inverters plus all inspections and permits – cost between $3 and $3.50 per watt.  Under NB market and sunlight conditions, solar systems pay for themselves in 15-20 years.

If those numbers make you frown, consider these three points.  First, once you have your own system, you’re totally protected from rising power rates.  In fact, the quicker they rise, the quicker your system pays for itself.  Happy face.

Second, if a 15-20 year payback seems long, pause for a minute and consider the payback of your current power arrangement.

Third, generating your own emission-free energy comes with a certain satisfaction and peace of mind that transcends economics.  The first persons to buy electric and hybrid vehicles probably also made their purchases based on considerations far beyond economics.

You can find installers via the yellow pages or an internet search.  Be sure the one you choose has certifications, and get references.  The website of the Canadian Solar Industry Association, www.cansia.ca, offers good guidance.

Add-ons

For true resilience, solar systems can incorporate batteries to supply household electricity during power failures.  In places where power rates vary by time of day, batteries offer a business opportunity: selling power into the grid at expensive times and recharging from solar panels or from the grid at cheap times.  Batteries are pricey, but costs are coming down rapidly.  The next big thing will be electric car batteries that can be charged by solar panels.

Aside from solar panels, there are even more ways to take advantage of free energy from the sun.  We’ll cover those next time.