Ice on PV Solar Panels

Iced Up Solar Panels

A quick comment about ice on PV (and likely other) solar panels.

My solar panels are quite flat - about 15 degrees up from the horizontal.  Its all related to the wind loading on the roof / ballasted mounting trays.

They do get iced over periodically - freezing rain, melting snow, ice storms - a variety of meteorological challenges.

I have found that if you can keep the snow off them with regular / frequent (daily) sweeping, then the heat generated by sun on the panels will clear the ice (mm) in about a day. Unless its really thick (cm), when it might take a week.  PV solar panels run warm because they are a near-black colour, and this clears the ice naturally.

Please note that it won't clear deep (cm) snow because snow prevents them from warming up.  The whiteness of the snow reflects the sun, especially when compared to the energy absorbed by the black solar crystals, even through clear ice.

So far I have only tackled the clearing ice from the panels only once - following a major ice storm that accumulated well over an inch of ice on all the panels.  After a few days of melting, I was able to gently lever the remaining plates of ice from most of the panels, but was constantly petrified of breaking them.  Not for the faint of heart.  Not sure that I would do it again, mainly based on the risk of panel breakage relative to the speed at which snow-free panels can clear themselves.

It is my experience that I sweep the panels free from snow and heavy frost about 15 times per winter season. Usually before 9 AM.  

Here is today's power chart.  The panels were swept between 10 and 10:15 this morning.

It is the difference between Wh per day and kWh per day, and the latter pays the bills!  I need 6 kWh each day to pay for the loan. I should get it today, but would have achieved it more easily if I had swept the system at 8:30.

If I was doing it over - another PV system from scratch - I would look at more steeply angled panels right up to the 43 degrees that are theoretically optimal here in Toronto.  That angle might help with shedding of snow (reduce the need for sweeping) and the draining of rain water.  However, I would also have many fewer panels because of the shading.  If you need 60 or 80 degrees of slope to shed all snow, then you will need a large or steeply sloping roof if you want an numerous array.

Hmmm.   Might have to do some more modelling of the performance vs the panel geometry.

So the bottom line is that to add to your bottom line you need to keep your PV solar panels clear and snow free if you want them to function properly in the winter. The ice will usually look after itself. 

Always be careful about roof top safety when sweeping. Falling off the roof is usually quite detrimental to one's health and well-being.

A Little Icing On The Scuppers

Iced - Up Scuppers on a Flat Roof

A couple of days ago we had a small ice storm (January, 2018). Rain, at +6C, transitioned to freezing rain around 0C and the ice started accumulating on the roof in front of and inside the drainage scuppers and down the drainage "rain chains", as the weather got colder.  It also accumulated on the solar panels as well.

Frozen rain all the way up
 to and through the scupper

We have eight scuppers. All are partially blocked / iced-in, several are mostly blocked and a couple are completely iced / blocked.

The first time this ice blockage happened I rushed up to the roof with kettles of boiling water, a heavy duty hairdryer, and a bucket of anxiety laced with a pint of adrenaline. We got them open, with some effort.

Hindsight being 20/20 I now use Plan B.

Following consultation with the manufacturer of our white TPO roofing material, it has been determined that TPO is not sensitive to common salt : NaCl, especially in the clumped form used in domestic water softeners.

A heap of salt.

So today I carefully deposited about 3 litres of water softener salt upstream from / on top of each scupper.  The 3 L volume is based solely on the capacity of the windscreen washer container that was pressed into service to carry the stuff up the ladder.  

The standard 3L container

This is a "3 L" session: a bit larger than "several hands-full", or a "litre (yoghurt) container", but smaller than a gallon or half a bag of salt. 

As the weather warms and in time, the salt will burrow down and melt the ice that plugs the scuppers.  Any spare salt will hang around keeping the water near the scupper a bit saline and liquid and flowing.

Salt within the scupper proper.

In a couple of the scuppers I actually put a handful of salt directly into the opening of the scupper. Safe access was the determining factor.

I might need to add more salt later in the winter, especially if we get another freezing rain / ice event. 

I can see one of the scuppers from my office window, in some detail, and can monitor progress, or the lack thereof.  This one is the "canary in the mine", and 

the indicator of risk.

I will concede that this is not the first time I have used salt in the scuppers.  For the first 2-3 years we were here I would add about half a bag to the front of each scupper in December when access is easy and distinctly safer. Never had blocked drain problems.  

Last winter I was away for the snowy part of it: no problems.  Likely by good luck and not good management.

This winter I was slow off the mark, and for my sins, had to remedy the problem in arrears and under more arduous conditions.  

Next winter I think I will revert back to the "half bag in snow-free December" system.

Costs, worth

What Did It All Cost?

The sixty four million dollar question.

The initial suggested price was "about $20,000".  This number was based on a site inspection and discussion by a green roof landscaping professional whose judgement we trusted. (And still do)

When we signified "interest' and asked for a detailed budget another number came back. I offered to provide a unit of "grunt labour".  The quote was then around $40,000, using "around" very loosely. This price was based on another site inspection and discussion with the green roof installer (contractor) 

That $40K budget was declined as being unworkable, and we proceeded to activate Plan B - Do It Yourself".

All things considered, our roof costed about $200 per square metre for all the things I had to spend money on. Materials, delivery, hoisting, permits and approvals, 3rd party technical support.

The City Eco-Roof Grant covered $75 per sq m - abut 1/3 of the materials.

To which you add "labour".  Realistically, commercial labour could double your cost for a simple installation, or treble it for a fussy installation. I think of ours as a fussy installation.

As the say YMMV!   Your Mileage May Vary.

Is It Worth It?

We are still getting used to the roof.  Analysis over the next couple of summers will eventually show if there is any financial benefit.

In the mean time..

• The second story of our home is noticeably cooler, especially on the real stinky sticky hot nights.
• The storm runoff from our roof is substantially delayed and reduced in volume  compared to our immediate neighbours and their flat roofs.  Small storms just don't runoff - they get absorbed.
• Now that the roof has grown "up" an inch or two and can be easily seen from the street, it is a local talking point.
• The shrubs in tubs are quite eye catching as they leer over the parapet. They do need regular watering with the same frequency as the rest of the ground level garden.
• I have watered the roof garden only once in a dry spell in July.
• We have been videoed and interviewed three times (in three months) for television programs. One interview was for a Chinese language TV channel "with English interviews" that were dubbed over into Chinese language. Video clips on my F/B page.

July, 2015

August, 2015, with English Interviews

• The colours change from month to month - to be covered in another blog entry.
  
• To which you can add 3 Open Houses for local community organizations and a date, Saturday 3 October, 2015 2:00 - 4:30 PM), with the OSEA "Green Energy Doors Open '15"  event.  Ontario Sustainable Energy Association (OSEA).

Shrubs In Tubs - Part 4 - Installation and Planting

Shrubs In Tubs - Part 4 - Installation and Planting

The planting of the shrubs is a bit tricky because I did not have access to a mechanical hoist.  

Friend Lino, the framer for the houses behind ours, did give us a lift with the Load Distribution Pads, and the two planters, but he was away on the day when I finished the installation.  Lino has a zoom boom and is very gracious when we needed a hoisting hand.

The installation of the shrubs into the tubs was fundamentally the same as on the roofs.

Two layers of drainage material were fitted to the base.

It was then covered with  a layer or two of the felted water storage material, cut to suit the geometry of the tub or the planter.

The tailoring of the storage layer to accommodate the circular geometry of the tubs means that there is quite a large area of overlapping material.  More storage capacity.

The containers were then filled "3/4" with the same mineralized growing medium as was used on the roofs. It is known as XTerr from Xeroflor.

The last 1/4 was a mixture of growing medium and "triple-mix", mainly because I had he triple-mix available (left over from last season) and I wanted to add more basic nutrients to the immediate growing zone.

Plantings.

There were chosen for their tolerance of full sun, a bit of heat, and modest water.

The two planters received a juniper each.  It is hoped that these will grow up a bit, but mostly sideways. The tag said 1.5'  (0.5m) high and about 3' (1m) wide.

The following material was planted into tubs.

• Pom-Pom Pine - Pinus sylvestris '(pom pom)' - ours has only one pom so it is not really a pom pom.
• Cascading White Pine - pinus strobus that may have been trained in its youth
• Two Tree Peonies- Paeonia suffruticosa   are about a foot high now, but we have higher hopes.
• Climbing Hydrangea - I have added a trellis of bamboos to provide a some height to which it can aspire.

Irrigation. 
I have added a complete drip irrigation system, accessible from ground level. It is a Rain Bird Gardener's Drip Kit from Canadian Tire, about $60 (2015). I added a few drippers and a second circuit to support the climbing hydrangea with RainBird pieces from "Lowes".  Lowes has a good selection of individual drip irrigation components so you don't have to buy complete kits each time you want another pressure reduction valve.

The climbing hydrangea has multiple drippers because it needs more water than the others. As a rule they all get watered on the same frequency as the rest of our garden. 

West Trough

South Trough

South Trough

South Trough

South Trough

City Incentive

The City of Toronto Eco-Roof Incentive Program

You might recall from an earlier session that we had applied for a grant under the City of .  

Toronto Eco-Roof Incentive Program

In summary, the City will give you a grant of $75 per square metre to install a living / green roof on your own home.  

• You will need to make an application in advance to join the program (quick).  
• You will need to get a City Building Permit (possibly slow and time consuming).  
• Do the installation ( you control this part)
• Have it inspected twice - once for the Building Inspector for their sign-off of the Building Permit and again by the staff of the Eco-Roof Incentive Program. ( a couple weeks)

We had a very pleasant visit with them about a week after the installation was the finished.  The sedums had been watered, and rained on, and had recovered nicely from the ordeals of travel. 

There was lots of discussion as we were the only full blown full coverage residential building "in play" at the time.  They even brought out the Summer Intern as part of their on-the-job training program.  There was a form to be filed out, photographs taken "for the record"  and measurements confirmed, to be signed-off by the City  staff.

Six weeks later the cheque arrived in the mail.

I commend this Eco-Roof Incentive Program to everyone in Toronto.  It works simply and well. In our installation the City "incentive"  covered about 1/3 of our material and permitting costs.  

All things considered, our roof costed about $200 per square meter for all the things I had to spend money on.Material, delivery, hoisting, permits and approvals, 3rd party technical support.

To which you add "labour".  Realistically, commercial labour could double your cost for a simple installation, or trble it for a fussy installation.

Sedums for the Main roof

Sedums on the Main Roof

The next two days were the culmination of almost 14 months of dreaming and scheming , hatching and planning, designing and organising and grunting.  It seemed like a long flog but we were looking forward to its end.  

The sedums for the main roof arrived on a big truck with a extendable boom like a HIAB crane.  It could reach up about 40 feet and could swivel its forks around.

I need to apologize for a complete lack of pictures here as my brain faded completely. Si you'll the thousand word version.

The product we installed from Xeroflr was their XF301 Sedum mat.  It is a field grown product.  It was delivered on a Connons truck so I assume it was grown by Connons on one of their Waterdown farms.

It was based on a layer of drainage material weave side up that had one layer of water storage fleece below it.  The open weave of the drainage material was filled with GM (growing medium) into which a range sedums had been grown.  By my count we have 8-10 species, although a couple predoominate.

The mats came rolled in 1 m by 1 m sections. Each roll was 1 m long by about 0.4 m in diameter, weighing about a gazillion pounds. About 40 or 50 lb.  Quite heavy and unweildy. They were delivered with 54 sq m ( about 550 sq ft) rolled up on two pallets.

Aknwloedging the reach of the crane, we elecete to lift them in batches of 6 -7 beacuse that matched the distribution of our temporary staging zone / landing pads.

S, with teh drivers help we rebundled the rolls intoa spare pallet and starting hoisting them up toteh roof. Whih took a couple of hours.

Then, with the trusty support from my able assistant (son, 28) we unrooled the mats and fitted them on top og the GM.  This brought t top of the installation up to be about 1/2 in above the level of the perimtere rail. Which felt fine to me.  

There was quite a bit of cutting and fitting to manage the smaller areas and shapes.  Initially I used a pair of scissors, for about 2 inches.  Then I tried a heavy duty Excato style knife and used a fresh blade every meter.  The GM is very bluntening. I would run out of blades very quickly. 

The solution is a 4" size angle grinder hired for the day or two.  

It was fitted with a "crack chaser" blade.  Did a really good job of cutting through the felted base material and the woven GM carrier.  Worth at least $40 a day!!!

To their credit, Xeroflor did ship a few more pieces than were strictly ordered, so we were able to sift and pick through the shipment to get really good mats for installation.

The sedums did come out looking floppy - flat and jaded - not unexpected from rolled material that had been scrunched into a roll then bounced at the way to the installation site. As part of the installation process I gave them all a good watering and they picked up substantially over the next couple of days.

So here is how it looked after we finished the installation.

Main roof open area

Up on the top of the 3rd Storey Walkout - close up.

Up on the top of the 3rd Storey Walkout.

The northern edge is tucked underneath the solar panels.

In some locations the GM filtered through the sedums.

Well, that's it. Jobs over. 

Over the next few months I'll put up some photos to show how it develops.  I'm hoping that the areas with GM showing will diminish as the sedums really start growing.

And I am looking forward to a cool summer.

For people who are interested in further discussions I suggest you leave a comment and I'll get back to you. We can remove the comment later to keep your coordinates relatively quiet. Or contact me via Facebook.
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Green but not living...

Poor Mans Green Roof!

There was a break of a few days between the hoisting of the growing medium and the arrival of the main load of sedums.

Winds were forecast.  As I didn't particularly wish to turn WIllowdale into a Saharan dust storm I applied one unit of green roof.

Green:  Ex Home Depot.

Ballast - courtesy of neighbouring building site  - on short term loan....