Winter - effect of snow Part2

So the snow built up until February 7th at about noon. That was when the snow guards holding back such a mass of weight said "no more". The courtyard area has a standing seam metal roof that pitches toward it and had built up with quite a curl of snow. I estimate that it was 4ft thick of ice and dense snow and went back a good 20ft from the eave toward the ridge of the roof.

Heavy snow weights about 20lbs/cubic foot. 4ft tall drift x 60ft long gutter x 20ft from eave upward = 4800 cubic feet of snow, or 96,000 pounds. That my friends is a lot of weight. Snow guards were torn free, and it crashed into the courtyard.

We have a mini excavator handy and dug a path to see what was buried. The inverter obviously took a hit on the roof as you can see from this photo. It is made to withstand outdoor environments, but never was envisioned to be under such a blast of weight. The blue canopy shown in other photos over the inverter was a light gauge cover to shelter a technician when they would service the equipment. Needless to say, it was destroyed.

The inside corner also house the air conditioning condenser unit. We created a canopy cover to protect the unit from snow during the winter time. Little did we know it would be crushed under the impact.

So my next post will discuss the recovery from the event.

Winter - effect on solar Part1

As we entered winter, I'm often asked - how does that affect the electricity generation from solar panels? Certainly the shorter daylight hours reduce the potential for kwh, but this year the question was more often related to the snow we have had. In CT this winter, our ground has been covered by snow since the Xmas-NewYear holiday until March. More than 90days! In fact, we received some record snowfalls.

Our panels are on a pitched roof and rather tightly spaced. Thus, the snow can start to slide off as you see in these photos. Our standing seam metal roof has snow guards to limit hazard below, because as you can see, when that accumulation slides, it slams (look at snow splat on pavement below). What was unexpected was how much snow we got (2ft in one storm) over the winter with no thaw period between storms. It did get to be a problem as to where snow could be pushed, and still maintain access to the yard for materials deliver.

After several storms, buildings started collapsing. Usually barns at farms or storage shed industrial structures that were light engineered on the limit of building code allowances. Still, we weren't taking any chances and started shoveling snow off our office roof (the only flat roof area we have). You can see by this photo that it was a lot of snow, up to our shoulder as we shoveled it away. The right photo is our courtyard area where some equipment for the solar array is located. The snow on the pitched roof area has curled and built up substantially. It couldn't be simply removed, and the buildup was worrisome.

It snowed and snowed and snowed!! It was quite the winter!! Despite the snow shed from our panels as shown in the above photo , we were getting a "DC fault" code causing the inverter to cease generating any electricity. We couldn't access the roof safely to confirm what was causing the fault, but the "DC" indication confirms it was at the panels. My next post will show the effects.

Public Charging of Snowy Tesla

The company has installed a weather proof electrical outlet, which is openly available to any electric car owner who wants to charge their car with free electricity generated at our location from our solar panel array. You can actually power your electric car with clean energy from the sun generated at the location where you top-up your battery.

Today we had another visitor take advantage of the offering, this time from Tesla Motors themselves! Michael Sexton, Senior Sales Advisor for Tesla Motors in New York City stopped by to visit on his way into New Haven. I showed him our manufacturing operations, we had lunch, and then he left with a full "tank" of sun juice!

As you can see, when he left, the snow was accumulating. I'm often asked how the Tesla Roadster performs in snow. As Michael illustrates - quite fine. He has snow tires mounted, and with the car's electronic traction control, it performs quite well. In fact, the battery weight is perfectly distributed over the tires of the rear-drive car.

As the Tesla illustrates, battery operated vehicles, including delivery trucks or fleet operations, need not be worried about cold weather or slippery surfaces. It is a vehicle like any other, but simply is powered by electricity rather than petroleum.

NOTE: It wasn't that long a stay to charge up the car, it started snowing during the first photo and was coming down at a good pace by the time he left.

Sunny Statistics 2010

The PV Solar System has completed it's 2nd Electric Year (2009Dec17 thru 2010Dec19). As comparison, look to the results for the 2009 Electric Year found hear.

For the 2010 Electric Year:

• The system was in place for 368 days (29 days of which there was no production due to equipment issues, snow load prevented access to equipment repairs in Feb/Mar).
• The average system output was 330kwh/day.
• The average consumption of our operations was 295kwh/day.
• Highest daily electricity generation was May10 with 724kwh
• 112% of consumption was generated from the PV Solar System.

January, November and December (and March due to equipment shutdown) were the only months when the PV Solar System didn't generate more than our entire operations electricity consumption. Since the system was installed on 2009Mar23, enough electricity has been generated on-location to power all of the company's operations.

Recognizing the excess generation capacity, during this year, items that were powered from other sources were replaced to electricity fueled such as hot water heaters and one vehicle vehicle. A sewer pumping station that was operated separately from our company previous to 2010, but which served our property and that of 3 adjacent parcels, was connected to our infrastructure and is now powered by solar generated electricity.

With there still being an excess of power after these changes, further avenues of efficient utilization and conversions will be examined in 2011.

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Solar Panels on Frosty Morning

An interesting thing regarding solar panels is their configuration or setup. Our 525 panel array is configured so that several panels are connected in series as a "string", and then combined with other strings to send their DC current to an inverter where the output becomes AC current.

One design challenge is that the panels in that string need to be working well together. If 3 out of 7 panels in a string are not functioning - the entire string is unable to make production. On Nov1, we had an exceptionally clear and cold day. The panels had a frost that settled on them, and with the early morning sun rising clearly and slowly, the melt of the frost followed the shadow line as the sun rose in the sky. As you can see by the above photo, that meant that some panels, though being struck by sunlight, were unable to pass along their energy generation because other panels in the string were not producing energy due to frost blocking the light.

One solution to this is micro-inverters that would convert the DC current on each individual panel into AC current. It is an interesting concept, which this NYTimes article discusses more.

The photo is from 8:30am, and the array kept going in and out of operation as the sun glinted just enough light and energy on the threshold of operating. During the day total, there were 452kwh generated, the most in nearly a month.

As of Nov1, the array has generated all electrical needs for the company, even with us switching gas heaters to electric and adding an electric car that charges it's battery here. In fact, the array generated all the needs, and created excess of over 14,000 kwh. The credit of kwh generated and pushed to the grid beyond our consumption pulled from the grid, will be drawn down upon during the winter months when we do pull more than is pushed to the grid.

Hot Water Heater - Electric vs Gas

The hot water heater in the manufacturing area serviced wash basins and a bathroom. It was gas fired, 50 gallons, and needed replacement. We switched to a 6 gallon electric which we believe will yield substantial savings.

A physical review revealed that use of hot water occurred only at end of work periods (break-time, lunch, end of day). Otherwise, the system was maintaining 50 gallons of hot water during off periods (such as evenings and weekends).

An on-demand system would not work due to the heavy load that occurs upon lunch time as an example, when all the workers are using actively washing up before a meal.

A 6 gallon tank was found to be the right size for our peak use. The tank takes up less room, and doesn't require the venting like the former natural gas fired tank.

The comparison of costs and determining payback of investment is offered via this government website.

The system has been in place for 2 months, and functions as projected. We have ample electricity surplus from our PV solar array, so we have eliminated a natural gas purchase for the energy, as well as have eliminated the pollutants from burning the gas. All hot water in our facility comes from electric heaters, with electricity gathered from our Photo-voltaic array of panels.

Electric Vehicle Delivery Truck

Electric delivery vehicles are a possibility of the future, which is why we are currently testing the feasibility via the electric passenger vehicle (the only pure EV available is the Tesla Roadster).

Our typical market served requires a 150mile round-trip capability. Currently the trucks being tested or shown in auto-shows have a 100mile range (and that is not descriptive of the load they may carry).

This link provides a glimpse at what may be to come for larger vehicles, and this link shows that smaller delivery vehicles powered by electricity (solely) are becoming available (to fleet owners).

Images drawn from and copyright autoblog.com