North-Eastern Coastal Solar Questions...

[hightecrebel]

Anyone on here from a "north-eastern" coastal area (Maine, New Hampshire, Nova Scotia, Newfoundland, etc.)? I'm trying to plan out my system here in mid-coast Maine, but in the various resources I've been using I've found little to no accounting for "coastal effect" weather patterns in the winter, so I was hoping to pick your brains about your experiences. Mainly the following:

1. How big of a drop do you experience in generation, summer vs winter?

2. How big of an issue is freezing rain/sleet with the panels compared to snow, and how do you deal with it?

3. Any issues cropping up from the salt in the air fast-tracking corrosion?

4. Any special considerations for systems prior to a Nor'easter?

5. Any odd/unexpected issues I should be aware of that will crop up later?

 

[12VoltInstalls]

How big of a drop do you experience in generation, summer vs winter

I’m vermont not coastal. But on cloudy days that aren’t heavy overcast you can expect 10%-15% of ‘normal’ production many days but sometimes 5%.
You are probably less regularly cloudy than here (believe it or not) but basically you should plan for no/low production days with your batteries and a generator. I’d suggest planning two full days of battery (that with ‘some’ production can extend several days some of the time) and not buying a HUGE generator but rather having a generator with ‘economy mode’ that can run ~30% while charging the batteries at max capacity of the AIO charger.
If your sensitivities are different that’s fine.

How big of an issue is freezing rain/sleet with the panels compared to snow, and how do you deal with it?

Again I’m not coastal. But I circumvented ice and snow by mounting the panels vertically. At our latitude you “lose” some of the potential harvest in winter by not being ideally angled 90* to the sun but a couple extra panels generally compensates for that. However, you will never lose 100% of production potential due to snow or ice. You won’t have to remove snow.
You do “lose” a lot more in summer with vertical panels as the sun angle is much further off. However, you can either provide for tilt adjustments for non-freezing seasons, OR if your quantity of panels has been planned robust enough for winter production goals you will get so much sun harvest in summer that adjusting them could be irrelevant.
I have found even a 1/2” of snow or a coating of ice pretty much means zero production.

Any special considerations for systems prior to a Nor'easter?

There are tools online that factor for wind and live load weather potential. If you do that properly other than maybe addressing flying debris you won’t need to do anything extra.

Any odd/unexpected issues I should be aware of that will crop up later?

Properly support and protect your solar panel wiring and that’s handled.

 

[hightecrebel]

But I circumvented ice and snow by mounting the panels vertically. At our latitude you “lose” some of the potential harvest in winter by not being ideally angled 90* to the sun but a couple extra panels generally compensates for that. However, you will never lose 100% of production potential due to snow or ice.

By vertically, you mean legitimately vertical, straight up and down not tilted at all? I hadn't considered that as an option. Going to need to change my wind calcs now and shift my planned mounting spot a bit.

Thank you for responding with your experience.

 

[WindWizard]

1. How big of a drop do you experience in generation, summer vs winter?

I am in west central Maine, so I cannot answer about Costal Maine. In the summer I produce over 1000 kwh per month and in the winter around 500 kwh, so at least a 50% drop in production. Snow will kill the production of power so I sweep the snow off the panels. I also adjust the angle of the panels which makes a huge difference in the winter.

2. How big of an issue is freezing rain/sleet with the panels compared to snow, and how do you deal with it?

There is not a lot that you can do with freezing rain. The panels warm up and it usually slides off. Snow kills the power production where freezing rain just diminishes it a bit.

3. Any issues cropping up from the salt in the air fast-tracking corrosion?

I can only speculate with the salt. I would think that it would leave a residue and panels would occasionally need to be cleaned. Aluminum seems to hold up very well in a salt environment so the panels should fair very well. Its the rails and other mounting hardware that will take a beating.

4. Any special considerations for systems prior to a Nor'easter?

They are brutal. The last storm through here uprooted a number of trees. My panels in the yard did very well. A set of three is mounted with 2- 2-inch galvanized steel poles 4 feet in the ground with concrete. The poles and panels were moving but they had no issues.

5. Any odd/unexpected issues I should be aware of that will crop up later?

Just make sure that you use quality components.

 

[peakbagger]

I am up in the mountains of NH but grew up along the Maine Coast before moving north after college. PV Watts does not handle snow cover well, but snow cover has its pluses and minuses. Contrary to what a solar salesman says, snow may not melt off quickly until there is sustained stretch of temperatures above freezing under the panels. If installed on an older home there is lot of heat leakage into the attic and out through the roof deck so it melt quickly (and create lots of ice dams along the way) but with well built energy efficient home that is not the case and attic temps will approximate outdoors. As you probably know snow has many forms and some tend to be real tenacious while others fluff off. The coast tends to get wetter storms and snow may be denser. The panels my be smooth but you would be surprised how much those seams between the panels will hold onto snow. Ideally panels are ground/pole mount with adjustable tilt and adjusted to be near vertical in winter. This is costly as the bottom edge off the array has to be well up off the ground as snow will slide down and build up at the base of the panels. I retofitted my pole mount with larger panels and I do need to run my snowblower along the front of the lower edge of the array or that snow buildup will cover the lower edge of the panels effectively taking than out of production. If you have string array, its a much bigger issue than if you have microinverters. The up side if snow can really increase the snows reflectance and the panels can put out higher than rated output on cold sunny days. In general winter months have a lot of cloudy weather so just be conservative on generation estimates.

As for corrosion, yes its a problem along the coast. The debate is always how close to the shoreline is the "coast"?. If there is chance of salt spray coming inland to an array even if its only a few times a year, then corrosion should be planned for. The biggest tough spot is folks like me who use steel or galvanized steel racking. Solar panels frames usually have some sort of light coating that may give some galvanic protection when new but that coating will break down and there will be long term corrosion at the junction between the frame and the panel. If you buy aluminum racking and use stainless hardware its not an issue although right at the waterfront, keeping wiring connections from corroding is an on going battle. BTW contact between cedar siding or pressure treated wood and steel is also a potential corrosion point. Make sure that when running conduit use coated or stainless screws rated for cedar or PT, I have seen a couple of installs both solar and non solar where conduits lost all their hardware in just a couple of years.

I am in high wind zone (5 miles from the top of Mt Washington. A properly designed and installed array should not have issues with winds, the buildings they are attached to usually are the weak point or shortcuts in installation. I have seen my share of wind failures over the years as an engineer in every case its poor installation. Finding the center of rafters through a roof is PITA and contractors are infamous for missing the center line and in many cases missing the entire rafter. There is lot of wind uplift on the upwind side of an array on a roof and if the fasteners are just screwed into decking they may lift off and when they do they tend to rip off like a zipper. A building inspector rarely if ever will pick up on these details and even a third party inspector may miss out on it.

BTW, given my comments on panel angle you might think I am fan of two axis trackers. I am not as they are quite expensive and prone to failure in harsh conditions. I have several All Earth trackers in my area bought by people with poor math skills, and more than a few of them seem to go out of service for days if not weeks. Just a lot of things to go wrong and with the high upfront cost its rare that the economics pencil out.

 

[12VoltInstalls]

vertically, you mean legitimately vertical, straight up and down not tilted at all?

Yes. 90* from horizontal
Here in the northeast kingdom of Vermont roughly 55-60* from horizontal is about close in winter whereas ~45* in summer is close to optimal. So the winter sacrifice is smallish. There’s calculators online for estimating various irradiation profiles.

 

[peakbagger]

My pole mount and wall mount have three settings based on my being a bit south of the Northeast Kingdom of VT (I am 44.38 degrees north latitude. Part of the kingdom can be over 45degrees. I rounded mine to 45 degrees. I set my mounts at plus of minus 15 degrees from 45 degrees. So 30 degrees from vertical in the winter 45 in the spring and fall and 60 during the summer. Even at 30 degrees in the winter the panels may take a few days to melt off stubborn snow, although once a part of the panels are exposed the melt off speeds up. I also have roof mount that is around 55 degrees year round. If I get a heavy snow storm and dont attempt to clear it, the snow can crust up and it can be weeks before it clears. Its on full dormer cape so the edge of the roof is 2 stories tall. I have a roof rake and can get to the lower edge. I find if I can expose the edge of the shingle roof below the panel and get air flow under the panel reestablished plus exposed the lower edge of the panels I can speed up the melt if I have a sunny day. It feeds a string inverter and on occasion snow will slide down the face of the top row of panels and then refreeze at the horizontal seam and its just enough to short them panels. If I get heavy snow and it seals off the top edge of the panels, the melt takes longer as air flow under the panel gets stalled.

I have seen vertical panels under an overhang on remote buildings that need power in the winter. The sun reflecting off the snow offsets the excess angle and snow rarely stays on them. The trade off is they are pretty useless in summer if the overhang shades the panel. If its really snowy year, slow sliding off the roof can build quite a mound of snow in front of the house so the panels need to be well off the ground or they risk getting a snow along the lower edge.

My original array, now 22 years old is a wall mount, over an angle bay window, it pivots at the top. I use the same angles as my pole mount. The overhang really does not shade it from 9 to 3. I use a wooden pole and floor jack to adjust the angle. It takes me about 20 minutes to change the angle. Heat from the angle bay window tends to give it a head start on snow melt. It could easily go vertical, but the angle bay gets in the way. Thats an old photo, there is now another array on the roof over it that is flush with the roof.

BTW the solar hot water panels used to be flush with the roof but it was way too much heat in the summer so I rotated them up to give me more hot water in the spring and fall. They run off a 12 volt circulator pump fed from the PV panel on the corner of the panels. It is starting to haze up a bit as I got it used and its 1999 vintage but still runs the original DC pump. The 4 PV panels are Sharp brand that I got a "smoking deal" on for $6 bucks a watt At the time a panel like on the SHW system was close to $10 a watt.

 

[12VoltInstalls]

The sun reflecting off the snow offsets the excess angle and snow rarely stays on them

That is real. In my location a couple miles uphill from where I am I had 400W of ESE facing panels that went into shadow by noonish. I could see many days where they still made 150-200W facing away from the sun in snowcover season. In summer clear skies it’s not uncommon to see over 100W 140* from the sun.

If I get a heavy snow storm and dont attempt to clear it, the snow can crust up and it can be weeks before it clears

You are more patient than I LOL
In my setup I only lasted a couple or three snowfalls - and therefore getting no charge - and everything went vertically, adding a few panels to exceed any loss due to angle. I get some charge nearly every day including snowstorms.
Not everyone can accommodate this arrangement but it works pretty well for me with ~2800W total of vertical panels- I put ~1800W on my shop’s SSW wall and 400W facing ESE

Many would argue my setup isn’t ideal; I’m wasting watts; I’m leaving a lot of power on the table. I’d agree. However, I didn’t build it to be ideal- I built it to do what I need and it does that.

 

[peakbagger]

I am normally grid tied with a grandfathered net metered rate plan which is as good as it gets with surplus generation so I really can live without generation for a few days. I normally rake my pole mount and my wall mount when I am cleaning up after a snow storm. My roof mount can be cleaned using a home brew curved top rod and 5 extension poles for my roof rake. I have to do it "blind" from the ground but I am retired so I do usually rake the roof array. The key to the roof array is it has to be raked soon after a storm as once there is sunny stretch it will crust up and then its not coming off until a warm up.

 

[darkskies]

I'm 30 miles or so, inland from the coast in NH. Roof mounted system at about 42 degrees. Well insulated home.

Regarding production, May through August are the best months, producing 1.4 - 1.6 mWh (granted with increased consumption for July/August). November through March are 400 - 700 kWh, so 25-50% of peak. I found PVWatts calculations to be very optimistic, although I have some shading from tall evergreens that I cannot remove, and from a perpendicular roof that blocks some of the panels.

Regarding snow, I find that in most cases, the snow will slide off, after a day or two, which is usually how long it is before there is some sun or limited clouds to produce anyway.

One thing to note, however, is that the snow on the roof, when it comes down will double or triple the depth on the ground and it will be hard packed and HEAVY! In our case, this means I have to be very diligent about keeping the rear deck clear, or I'll end up with a snow pack that I cannot remove and therefore get to the grill. If this were on the front of the house, that could pose issues for entrances.

We've seen winds here, up to 40-50 mph (just recently), with no problems. I'm pretty much relying on my installer using quality equipment and installing it properly. From what I read, the IronRidge rails are rated for hurricane winds. More of a concern, IMHO, is the effect of wind on nearby trees.

 

[740GLE]

Coastal meaning Damariscotta/Ellsworth or can you see the ocean from your house?

With this recent weather pattern of this winter it’d be best to expect a huge hit in winter time due to fog and overcast days more so than snow pack/ice. The gulf of Maine has been so warm (except for that one week a year cold snap) those really on the coast don’t have to deal with the white stuff very long even after a nor’easter.

 

[hightecrebel]

Coastal meaning Damariscotta/Ellsworth or can you see the ocean from your house?

With this recent weather pattern of this winter it’d be best to expect a huge hit in winter time due to fog and overcast days more so than snow pack/ice. The gulf of Maine has been so warm (except for that one week a year cold snap) those really on the coast don’t have to deal with the white stuff very long even after a nor’easter.

Technically it's Muscongus Bay I see from my house. I'm not right up on it, but yeah, not too worried about the snow, but we've had quite the freezing rain/sleet issue the last few years so I'm trying to figure out how to mitigate that along with the salt & wind. Fog and overcast will happen no matter what I do, so just trying to make the best of it before I do.

I've had a small system on my shed for a few years, but it's shaded in the winter so I never really bothered tracking how the weather effects it.

 

[Hogheavenfarm]

For Snow I just broom off the panels, as they are mounted on a semi-freestanding support, and they are are a steep angle, maybe 66 degrees off horizontal, I dont remember. Freezing rain no real issue. Harvest is very low in December, will pick up gain in late january. I don't have a big system , maybe 2000w of panels, so I went to grid for the freezers that run off it for now. Noreasters are more of an issue due to the steep angle, I used hurricane ties on all my connections.