Solar on a Strata – Over Three Years

Note: This is another entry in the ‘Solar on a Strata’ blog series. I haven’t done a blog entry since September 2016, because there isn’t much to report. The system continues to produce electricity every day, without maintenance. Here are some details: 

Monthly Electricity Output to June 30, 2018 – Graph by Bruce Mackenzie


As of the end of June 2018, the system has produced 53.8 MWh (Megawatt hours), aka 53,870 kWh of electricity. This is AC power delivered out to the building, as measured by the inverter. It’s about 5% over what we expected from the most accurate pre-installation prediction: See

The initial analysis predicted it would supply about 1/3 of the electricity used by the strata common area. As reported in the last blog, the strata replaced the High Pressure Sodium exterior lights on the building with LEDs, reducing the overnight demand by about a kilowatt. In the 12 months since that change, the solar panels supplied about 47% of the electricity used by the strata common area.


Monthly Electricity Output to June 2018 – Table by Bruce Mackenzie

Financial Return 

It’s only fair to calculate financial return over full 12-month periods to capture the huge seasonal variation in sunlight. The panels have been connected and on the full net metering billing since mid-August 2015, so I’ve chosen from September 2015 through August 2017 (two years). During this period they saved $4,653 in electricity, a ‘dividend’ of 9.9%, or about 4.95% per year on the installation cost of $47,000. This is right in line with the 4.9% Simple ROI I predicted at the 2015 AGM presentation to the owners when they decided to proceed. 

BC Hydro Invoices

The August invoices show the most change, of course. August 2014 was $707.46, August 2016 was $39.96 and August 2017 was $64.06

Solar Eclipse 
No magic here, but it’s easy to see the eclipse cutting production from 08:50 to 11:05 on August 21. The loss was about 8 kWh, costing about $1.13.


Solar eclipse output dip – graph by Bruce Mackenzie

The Strata Council was very supportive in having tours of the system on September 23, 2017 as part of Green Energy Doors Open – an event sponsored by BCSEA in 2017.  Ten people showed up for three tour times. 

The ventilation fan installed in the electrical room worked fine over the summer, and the room has been cooler. I had a recorder there until the end of June, and it was almost always under 30 degrees C, with a couple of bumps to 32. 

The Inverter continues to report its output and condition through the Fronius website <>.  I receive weekly and monthly emails with output summaries, and also if there is a problem in the system – to this point only with the Internet connectivity. 
Fronius changed its public website so that we can now only see two days of previous output profiles, although monthly and annual summaries are still available. 

Strata Annual General Meeting 
Central Park Strata held its AGM in February, and I offered to meet the owners for a brief report and any questions or concerns. The President responded “We have asked around about the solar panels, and  nobody really showed much interest in learning more about them. I think that overall, people are just happy that they will eventually pay for themselves and generate power, but that’s the extent of their interest….” 

It seems like the system has become part of the furniture. 

Lobby Display 
As usual, the only trouble from the system was from the lobby display. This time the LCD panel that shows the production failed in the summer. I purchased a replacement at the Salvation Army for $10. It’s a bit different shape than the last one, so I had to modify the wood frame it hangs in. Again, this display has no effect on the actual electricity production which continues uninterrupted since June 2015. 

Too Much Power ? 
This is the one for geeks. As mentioned in my last blog entry, some of the electricity the panels produce in the summer displaces ‘Tier 1’ electricity, which isn’t as expensive as ‘Tier 2’. When we designed the system, the goal was to NOT generate enough to displace ‘Tier 1’. However, with the LED lights, it turns out that for the July and September billing cycles, the solar panels have cut into the Tier 1 rate. But I have done the calculation and this has only reduced the cost savings by $127 in the last two years. Not a big deal in the big picture. 

I rinsed the panels in spring of 2016, when they just had a bit of grit along the bottom edge. They didn’t seem to need any cleaning in May 2017 after our very wet spring. I checked them closely again in mid September ahead of the tours, and they had a bit of grit at the bottom again, but also a very thin layer of find brown dust which I thought might be from this summer’s forest fires. I gave them a better cleaning that time – used a bit of soap in two buckets of water, and a soft broom again. It took about an hour. 
However, there was a lot of rain last fall and in October I couldn’t find any grit left. I think my rinse was unnecessary – the rain would have cleaned them. 

Dust on solar panel, October 2017 – photo by Bruce Mackenzie

Hallway lights 

The Strata chose to replace the ‘dog dish’ CFL corridor lighting with new LED fixtures. I don’t know what this cost, but I saw a comment on Facebook that the hallways are brighter. I can’t detect any difference in the power consumption on MyHydro. The 6″ fluorescent U-tubes draw 13 watts (plus a magnetic ballast), and the LED lights are rated at 14 watts, so I wouldn’t expect to see a change. 

I remain happy to talk to anyone who is interested in following Central Park’s lead. My email address is on the ‘Solar on a Strata – Join Us?’ page. I have spoken/emailed with about 13 people. I don’t know of any who have gone beyond the investigation stage.

Next in the series:  Still Producing in 2023.

For lots more information, see my detailed ‘Join Us’ blog post.

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