Feature: Photovoltaics - it's the little things in solar that count

Tuesday, June 8, 2010

That's the advice of Thomas Boehni, a Swiss pioneer in solar energy with 18 years experience in roof-mounted solar systems. You can hear what he has to say at information sessions across the province in the coming weeks.

by JAKE DEBRUYN

There's something different these days about the rural landscape in Ontario. The green sprouts of corn, beans and wheat look the same as any other spring. It's the new green energy systems that are capturing everyone's attention.

Ontario's Green Energy Act and the Ontario Power Authority's Feed-in Tariff electricity program have kick-started significant investment in green energy technology, especially in rural Ontario. And solar panels are attracting a lot of interest.

Solar photovoltaic (PV) modules generate electricity from the sun. In many cases, a 10-kilowatt (kW) solar module system can be installed for under $80,000. And with the opportunity for a 20-year contract for 80.2 cents per kilowatt-hour (kWh) from the Ontario Power Authority, the economics are attractive.

With a yield of 1,150 kilowatt hours per kilowatt of capacity per year (kWh/kW/yr) on a well-designed roof-mounted system, these systems offer a return of $9,000 a year, or roughly 11 per cent return on investment. A tracker system that follows the sun through the day may do even better. 

Some Ontario farmers are installing larger roof-mounted systems. An existing barn with 10,000 square feet of roof space can install 130-150 kW, likely for $700,000 to $900,000, depending on local electrical grid capacity and on the structural capacity of the roof.  The Ontario Power Authority is offering 71.3 cents per kilowatt hour to solar systems that produce up to 250 kW.

But as people rush in to sign contracts and get systems built, solar system purchasers should be asking detailed questions about what they are buying and how they can get the most out of their system. With this in mind, the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and the University of Guelph Ridgetown Campus have looked to Europe for experience in their upcoming Solar Information Sessions.

Thomas Boehni is a mechanical engineer from Frauenfeld, Switzerland, with a passion for green energy. Eighteen years ago he installed his first barn-mounted solar system. "I got into this business because it is clear that in the future we will need to use less energy and produce more green energy," says Boehni. "For the sake of our children and the next generations, we need to make better choices today. It's the little things that count."

With similar Feed-in Tariff programs to Ontario's offering good electricity prices for solar systems, his business in Switzerland and southern Germany is booming. "Last year, we installed just under one megawatt (MW) of roof-mounted modules, mostly in the 10 kW to 100 kW sizes," says Boehni. "Solar systems are ideal because you can install them on almost any house, any barn, and any business."

Over the years, Boehni has identified some fundamental points to optimize a solar project. "You don't have to have a perfect set-up to make solar modules work," he says.

"But it pays to keep track of small improvements in efficiency. Again, it's the little things that count."

Boehni will be doing a series of talks at Solar Information Sessions throughout rural Ontario in June and July focusing on capturing the small efficiencies to make your system work best. These sessions will include speakers from the Ontario Power Authority, local electrical distribution companies and OMAFRA. The purpose of these sessions is to provide information about proper construction, efficient long-term operation, and awareness of processes, regulations and timing.

Here is a quick summary of Boehni's top nine little things that count, and their impact on the bottom line:

1. Point your modules towards the sun!  +/- 25% impact
South-facing modules are best. Trackers are even better. Boehni could talk all day about these basic facts. In Ontario, with a very shallow pitched roof, you can get away with a more significant east- or west-facing application, but you will pay for it in reduced yield.

2. Choose high quality solar modules   +10% impact
They say that when you buy quality, you only cry once. For modules that are going to operate for 20 years, you should buy the best. According to Boehni, high quality modules are more stable over 20 years, while the yield from low quality modules may decrease faster.

3. Pick the right inverter + 3% impact
Inverters convert direct current (DC) flow out of the modules to alternating current (AC) for the electricity grid. It is more important to get an inverter with a high "average" efficiency than one with high "peak" efficiency. Three-in-one inverters can deal more effectively with shading, and are cheaper than three smaller individual inverters. Boehni will explain these concepts further in the information sessions.

4. Pay attention to module output tolerance + 2% impact
Solar modules off the assembly line will vary in their power output.
It is important to purchase modules with a small power output tolerance
(e.g. plus or minus three per cent). Some manufacturers even offer "plus" modules with only a zero to plus three per cent tolerance.

5. Optimize air circulation +1.5% impact
While modules may sit in the blazing sun all day, they actually operate best when they are cool. Roof-mounted modules should be installed with sufficient framing to allow air circulation underneath. Raising the panels steeper than the roof slope provides significantly better air circulation, and it requires a setback between rows of panels to prevent shading. However, care needs to be taken to ensure the roof can handle the potential snow build-up that could occur with such a set-up.

6. Balance module and inverter power + 1.5% impact
Lower voltage input to the inverter provides the highest efficiency in the inverter, regardless of power output. Input voltage to the inverter can be reduced by reducing the number of modules per inverter. Therefore, your installer should optimize the number of inverters and the voltage on each inverter.

7. Connect similar output modules together + 1% impact
Modules that have been sorted depending on their actual output should be connected with similarly-rated modules to each inverter. Flasher data is available for every single module. For instance, for nominally 120 W modules, all the modules that are actually at 123 or 122 W should be strung together, as should all the modules at 121 or 120 W. The same with the modules at 119 and 118, and so on.

8. Ensure proper wire dimensions. + 0.5% impact
On the "DC" side of the inverter, only solar-rated wires should be used. On the "AC" side, common wiring practices can be followed. Care should be taken when the distance to the grid connection point exceeds 10 metres. 

9. Keep the panels clean + 4% impact
Believe it or not, keeping the panels cleaned off makes a big difference on returns.  For shallow-sloped modules (less than 25 degrees), semi-annual cleaning is best. On flatter roofs, or those that are dusty, you may want a layout that allows rooftop access in a safe manner for more regular cleaning. This will reduce your total area for panel coverage, but will make the best of what you have got installed. 

If you can control these small factors during construction, installation and operation, you can probably add 10-15 per cent in efficiency to your system annually. "These savings can make the difference between a good project and a great project," says Boehni.

Hiring a good engineer and electrician to deliver on the nine recommendations above will increase your profit.

For details about the Feed-In Tariff program, visit the Ontario Power Authority website: fit.powerauthority.on.ca

For more information about solar and other renewable energy opportunities visit www.ontario.ca/omafra  BF

Jake DeBruyn, P.Eng., is the New Technology Integration Engineer with the Ontario Ministry of Agriculture, Food and Rural Affairs.

Sidebar: The Solar Information Sessions

You can hear Thomas Boehni and various other industry and government representatives speak at OMAFRA/University of Guelph Solar Information Sessions at various locations in late June and early July. Sessions will be held during the evening (7-10 p.m.) to encourage farmers to come out during an otherwise busy farming season. Here's the schedule:

Monday, June 28       Ridgetown
Tuesday, June 29       Woodstock
Wednesday, June 30     Mount Forest
Friday, July 2             New Liskeard
Monday, July 5          Lindsay
Tuesday, July 6         Belleville
Wednesday, July 7       Kemptville
 
To register or to get more information, contact the OMAFRA Agricultural Information Contact Centre at 1 877 424-1300, e-mail ag.info@ontario.ca