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Thursday, February 21, 2013

Forward on Climate Rally; Washington, DC; 2/17/13

 

On Sunday, February 17, 2013 around 40,000 people met at the Washington Monument in Washington, DC to urge our government to take action on the burning of fossil fuels that contributes to climate change, and to ask the president to stop the Keystone XL pipeline that would bring Canadian tar sands oil to the Texas gulf coast. The climate change rally and march was primarily sponsored by 350.org, the Sierra Club and the Hip-Hop Caucus, but participants came from many organizations, including several faith-based groups such as the Sojourners. I went to Washington on one of 11 buses that carried over 500 people from our area to the rally.

On the way back from DC in the bus, we each shared one word that characterized the day. Words like encouraging, energizing, active, informative, generational, diverse, communicative, transformational, historic, loud, creative, and fun floated up from the tired marchers. When I got back and I saw the pictures that I took in this album, one more word to characterize the day was quite evident to me—happy. In almost all of the pictures I took, people were smiling. They were smiling about a large group finally coming together to make our voices heard on climate change. They were smiling about the chants we sang such as “Hey Obama, we don’t want no climate drama” as we marched around the White house. They were smiling that old and young alike were of one mind that there is no “Planet B.” They were smiling at the creative ways that people expressed their concerns about our energy and environmental futures. They were smiling about the shared purpose and the knowledge that something important happened on this cold and blustery day in February when people raised their voices. It was a good day.

 

     

  

Wednesday, November 14, 2012

The Colors of Spain

video

Here are a few pictures from our trip to Spain in October 2012.  The pictures were taken at various locations in Madrid, Sevilla, Écija, and Córdoba.

Friday, March 9, 2012

Grid Tie Solar Plug and Play in the US

 

While other countries have commercially available grid tie solar plug and play systems (http://solar-power-station.co.uk/), the US does not.  At least one US company has committed to such a product (http://clarianpower.com/), but it is not yet available.

As part of the US DOE’s SunShot initiative to support a multi-source approach to meeting the country’s energy needs, a meeting was held in Washington, DC on October 27, 2011 to focus on the development of plug-and-play solar technologies in the residential sector. The purpose of the workshop was to identify the current barriers and possible solutions for these technologies. Over 60 people attended the conference, including representatives from utilities, code officials, inverter companies, PV module companies, and installers.

Here is a summary of the results of that meeting:  http://www1.eere.energy.gov/solar/pdfs/solar_plug_play_2011.pdf

Although there seemed to be a lot of off-topic discussions, a few big issues emerged:

1.  How to deal with current permitting requirements for electrical issues. 

Suggestions for dealing with electrical safety issues to avoid permitting and inspections by local code enforcers seemed to be fairly straightforward:

--UL listing for PV system: NEC 90.7 Equipment that is listed “need not be inspected at the time of installation.”
– Develop a standard PV plug at the utility meter (or elsewhere)
– Changes to the National Electrical Code are required (we are on writing code council)
– Smart, PV-ready circuit breakers.

2.  How to deal with current permitting requirements for structural safety issues.

Suggestions for dealing with structural issues such as modules resisting windy conditions and PV systems compromising building structures were less imminent and not as practical.

--Can we build a PV system on a residential home that is
• Light-weight (polymer)
• Requires no roofing penetrations (can’t have roof leaks)
• Requires few (or no) tools to install
– Can we design a PV module/array that fits around a roof like a fitted sheet on a
bed?
– Establish requirements for solar ready houses (standardized roof jacks)
– Consider composites, polymers… integrating frames and mounting systems can dramatically reduce weight.

3. There was also discussion about how to integrate Plug and Play Solar arrays with smart grid issues.

I learned a few things from reading the summit results.  The electrical safety concerns seem to be fairly easily overcome.  Many of the obstacles are not difficult safety barriers, but more code-related.  Limiting the Watt size of plug and play systems on each branch circuit allays overloading concerns.

According to NEC 90.7, UL listing is not required, but if non-UL listed equipment is used it must be inspected at the time of installation.  Some advocated a UL listing for the entire system (modules, wiring, inverters, connectors), while others advocated each component be UL listed. 

There are concerns about using the standard three prong plug to simply plug into an existing outlet.  They talked about developing a USB like plug specific to PV systems so people aren’t exposed to live conductors on the male end of the plug.    I don’t really understand the concerns here.  An anti-islanding grid tie inverter shuts off when it is pulled out of the outlet, effectively cutting off current to the plug, and protecting the user from contact with exposed conductors.  The British system uses a standard outlet connection with anti-islanding China-made inverters.

Given the seeming lack of consensus on the structural issues associated with attaching plug and play to buildings, it seems simply requiring ground mounting makes the most sense.  I think keeping people without fall protection off of roofs is a good thing.  Many commercial solar firms working on roofs don’t even provide fall protection systems to their employees, and there are several deaths from roof falls annually in the business.

As a result of the workshop, in January 2012 the DOE announced a 3 year grant program to fund studies on plug and play solar issues that came up in the workshop:  https://eere-exchange.energy.gov/Default.aspx?Search=plug&SearchType=.  It appears that it will be a few more years before commercial plug and play grid tie systems hit the markets in the US, and with the desire to incorporate smart grid components into the system, more than a simple inverter will be required.

So why is the whole issue of plug and play grid tie solar so important?  A 500 watt back yard grid tie system generates about 650 kWh of electricity each year where I live.  In my local utility area, that translates to about 9% of the average residential customer’s annual electricity use.  Besides saving money for the customers, widespread use of these systems could slow the need for new power plants and drastically reduce carbon emissions.  I also recently read the book “The Big Thirst” by Charles Fishman, and learned that steam generating power plants use over 200 billion gallons of water a day to make steam and cool heat exchangers (http://powerscorecard.org/issue_detail.cfm?issue_id=5).  Solar modules require no water for cooling.

While we wait for commercially available plug and play grid tie systems, DIYers need a UL-listed DC to 120V AC inverter, or guidelines for inspectors when non-UL listed equipment is installed, and code revisions that allow connection to the grid.  If other countries have already overcome plug and play solar obstacles, why can’t we?  As the world becomes flatter and hotter, is a three year wait for plug and play solar that is already available elsewhere acceptable?

Monday, February 27, 2012

Our Experience with the Giani Granite Countertop Paint Kit—February 2012

 
For several months my wife and I discussed how we could give a makeover to our old laminate kitchen countertop. We don’t have a big countertop. The sink countertop is L-shaped, 8 feet in length, with the L part extending about 18 inches from the 2 foot wide main section. We also have a 2 foot by 2 foot desk section that matches the sink countertop. All told, we have 11.5 feet of standard 2 foot wide countertop.

We investigated our makeover options in the typical fashion. After being shocked by the megaprice of granite, and even the $600 cost of replacing the existing countertop with another laminate top, we investigated tiling the countertop. I even bought a tile saw. Before buying the tile, we ran across some information on countertop paint kits, and visited the Giani Granite website http://gianigranite.com/indexcountertoppaint.html to learn more. Encouraged by the testimonials both on the Giani site and elsewhere on the web, we decided to try the kit. It appears that in the last few years Giani’s marketing strategy has been to give away kits to bloggers in return for writing up their experiences. We are not one of those bloggers. We bought the Giani Sicilian Sand kit on Amazon.com for $69.95 including shipping. Here is a “before” picture of our countertop:

Our countertop was in great shape structurally, but had many superficial scratches and stains.  The color also did not go with the laminate floor we put in a couple years ago.
 
There is a matching desk section that we use for the microwave oven.

After watching the instructional DVD and armed with the detailed Giani paint kit instructions, we started the project on Saturday morning, February 18. We were aiming to replace the sink with our countertop makeover, so I shut the power off to the disposal and spent a couple hours disconnecting the disposal, water lines, dishwasher and sink drain lines, and pulling up the chipped old 50 pound porcelain over cast iron sink. I found that the countertop cutout for the sink was too small for the Elkay Lustertone stainless sink we were planning to put in, so I had to spend some time enlarging the sink cutout. It was not easy because my jigsaw wouldn’t reach the back edge of the cutout due to the presence of the backsplash. After some effort I finally enlarged the sink cutout.

On Saturday afternoon my wife Jeanne and I scrubbed the countertop using SOS pads, and cut away the silicone caulking that had been used at the joint between the countertop and bottom edge of the backsplash, and where the backsplash and counter met the walls. While the silicone caulk cut away easily, it left a layer on every surface where it was cut away. We used razor scrapers, and even sandpaper, but we could not remove the silicone caulk residue from the Formica surfaces. Removal of all the residue is important because paint will not stick to the residue. Following the instructions in the Giani instructional DVD that came with the kit, we wiped the silicone caulk residue with isopropyl alcohol as instructed, but it did not remove the silicone residue. From reading on the web, wiping the silicone caulk with denatured alcohol only works if the caulk has not set up.
 
Frustrated with the several hours we spent trying to get the residue off, we decided to go ahead and roll the first coat black primer onto the cleaned countertop. After taping off all the edges and placing craft paper in front of the cabinets for protection, we rolled on the iron coat black primer. The primer went on well and completely covered the surfaces—except where the silicone caulk had been. Here is a picture of the areas where the primer did not adhere due to the silicone caulk residue:
 
Wherever there was silicone caulk residue, the primer did not adhere.  We skimmed over these areas with black, paintable acrylic caulk, then primed the caulk after it dried.  That approached worked well.
 
Sunday, February 19. After sleeping on the problem, we decided to see if we could cover over the silicone caulk residue with a paintable material. I went to our local Home Depot and got a tube of Dap Alex black colored paintable caulk, and on Sunday I put a very light skim of caulk over the areas where the primer didn’t adhere, blending it in with where the primer did adhere. After letting it dry 4 hours, I hand painted those areas with the little foam brush provided in the kit, and the primer adhered well. Due to the very light skim application, you really couldn’t see where I had applied the caulk. We let the caulk and primer dry overnight.

Monday, February 20. We practiced applying the three color coats with the pieces of sea sponge using the black paper supplied in the kit. After getting the hang of it, we started applying the color coats. In the Sicilian Sand Kit, the three colors that go on after the primer are feldspar brown, Inca gold, and then finally limestone white. There were several lessons learned in this part of the job. First, we learned to work in small two foot sections so the wet paint layers blend into each other. Another key pointer is to use the paint sparingly on vertical back splash surfaces and countertop edges because it will run. We had trouble getting into the corners with the sponges, so we used the recommended half inch brush a lot in the corners to apply the three layers of paints. When we finished applying the paint layers to the countertops we weren’t quite happy with the way it looked, so we decided to let it dry and work on it again on Tuesday.

Tuesday, February, 21. We noticed several areas where the patterns didn’t look random enough. Using all four colors to “fix up” the areas we were concerned about, we finally arrived at good enough. A key was reapplying black splotches in the areas where we had put too many colors. We let our color paint layer dry overnight and here's what we got:

The primer and color coats have been painted on, awaiting the polyurethane top coats.
 
For us, painting inside corners was difficult with the smallest sponge section.  We did most of the corners with a half inch paintbrush, and used the sponge to give it some texture.

 
Close-up of the color coats before applying the polyurethane.

 
Wednesday, February 22. We lightly sanded the color coat with 600 grit sandpaper and wiped it  with a damp cloth. After letting the damp surface dry for an hour, we rolled on the first polyurethane coat following the instructions. A key in this step is keeping the roller wet so that you don’t hear the SSSS sound of a dry roller rolling over the surface.
 
Thursday, February 23. Jeanne lightly sanded the first polyurethane coat with 600 grit sandpaper, and rolled on the second layer of polyurethane. When this coat dried, she was not happy with one section where the roller had dried, so she wanted to reapply some polyurethane in that area.

Friday, February 24. In the a.m. Jeanne lightly sanded the repair area, wiped it down, waited for it to dry and reapplied the polyurethane in that area to her satisfaction. On Friday night when Ken returned from work he caulked the interior seams with Alex 230 Crystal Clear acrylic caulk, and the areas where the backsplash meets the wall with Alex 230 brilliant white acrylic caulk.

Saturday, February 25. The new sink was set in place using Loctite Polyseamseal Ultra and the Elkay sink clips. The water lines, disposer, dishwasher and sink drain lines were reattached and the job was completed.

Our impression: This kit exceeded our expectations. The renewed countertops, new sink and new faucet transformed the look of our kitchen. We think the countertops look fabulous, and hope that they will provide many years of service.  Here are the results:

The top polyurethane coats gave the countertop a highly glossy finish.

Sink area.

 
Desk area.
 
Our "after" picture of the countertop.
March 22, 2012 Update:  It has been about a month now since we applied the last coat of polyurethane to the countertop. The top has held up well to daily use, but we have observed something interesting on two occasions.  Once, we set a pineapple on the countertop overnight with the cut stem side down.   When we picked up the pineapple in the morning, there were small blisters in the finish where the stem was on contact with the countertop.   You could feel small bumps on the polyurethane in that area.  We wiped down the area with a damp cloth, and then had to go somewhere.  When we came back a few hours later, the blisters had disappeared and the top looked and felt as smooth as if nothing had happened.
On a second occasion, my son put a hot coffee cup down on the countertop and left it in place overnight.  In the morning, there small blisters in the shape of a ring where the cup bottom had been in contact with the top.  We again wiped down the top with water in that area, and within an hour the blister ring disappeared and the top looked as if nothing had taken place. 
Perhaps our top has not fully cured and hardened, but it has been interesting to see that both of these “injuries” were “healed” by wiping with a damp cloth.
February 21, 2013 Update:  It has now been about a year since we did our countertop makeover. I have been very happy with how the countertop has held up in daily kitchen use during the first year.  I think it took about 6 months to fully cure the polyurethane top coats.  I say that because as mentioned in the update above, for about the first six months we had to be careful about leaving long-standing water on the top or you could feel the little bumps in the area where the water had been.  We noticed that his happened especially when wet cups were left on the countertop overnight and the countertop surface was wet under the cup for a long time.  When the counter surface dried out, the bumps always went away and there was no permanent damage, but we took care to make sure the top was wiped dry after we figured out what was going on.
After about six months, we noticed that long-standing water exposure to the countertop was no longer a problem, and I think it is because the polyurethane coat had fully cured.  If the polyurethane is truly an automotive grade coating as Giani claims, it makes sense that it would take a while to fully cure at room temperature.  In a car manufacturing facility, after the clear coatings are applied the cars are usually baked in a high temperature oven to quickly cure the polyurethane.  At room temperature, I think the curing process takes a lot longer, and in our case about 6 months seemed to be the time it took to fully cure.  Cosmetically, the countertop still looks wonderful, and still shines like new.  I am very happy with the new life that the countertop paint gave to my old laminate kitchen countertop.

Tuesday, January 3, 2012

My Problems with an E.F. Durand F-trigger Trombone from Great Tunes Direct (greattunesdirect) and USA Music Supply (usamusicsupply) on E-bay

In late August 2011 I bought a Brass Tenor F Trigger Trombone w/ Tune Slide” from Great Tunes Direct through their E-bay site.
 
When the trombone arrived, I played the horn for a few days, and noticed that the slide was grabbing at a few positions and did not slide as smoothly as I would like.  Within a week of receiving the horn (well within their stipulated 14 day return period), I contacted Great Tunes Direct in Twin Falls, ID through email to see if I could exchange my slide for one that worked better.  Christina, their customer service representative sent me a return email saying they would be glad to send a new slide, but that I would need to return the old slide to them at my expense. I agreed, and they shipped a new slide to me on September 23.

I bought this new trombone because I needed a larger bore horn (.547) for playing in a community orchestra.  The horn sounded very nice, and I was quite pleased with the new slide.  About three weeks after receiving the new slide, I started to notice a scratchiness in the slide movement.  When I pulled the slide apart to inspect the inner tubes, I found that one of the inner slide tube stockings had begun to lose its plating, and was pitting badly.  I had only used the slide for about 10 hours of total playing time.  Here are some pictures of what I saw when I inspected the replacement slide:





On October 19, 2011 I sent the following email to Steve Di Lucca at Great Tunes along with the pictures above: 

Dear Steve,
I recently bought a trombone from you on eBay.  After I received the trombone, I immediately sent the slide back to you for repair because the slide was grabbing in certain positions.  I don’t currently have the RMA number you sent to me before I returned the slide for repair, but the slide came back to me working well.  I have only been playing the trombone consistently for about 3 weeks now since I got the repaired slide back, and I noticed a scratching sound and feel in the slide other night when I was playing.  When I took the outer slide tube off the inner tubes, I saw that the nickel plating is chipping off one of the inner slide tubes.  I have attached pictures of the nickel plating failure.  I’m wondering if this could be related to the repair of the slide?  The slide has been very well lubricated over the last few weeks.

In any case, I really like the horn, and would like to have the slide replaced with one that works freely without binding AND has the nickel plating in good shape. I am currently playing in an community orchestra with an upcoming concert, and I can’t send you the old slide back until a new one comes because it is my only horn.  Can you please help me out?  I was promised a “High Quality” instrument when I bought it from you, and so far, it has not lived up to the promise. 
Thanks for your help.

I received a response to this email from Christina, and she said she would follow-up with Steve.  I didn’t hear anything, so I gave a call to Steve Di Lucca to see if we could resolve this problem.  Steve said  they had been selling this horn for many years and had not had any problems with it.  He told me that I might have “acidic saliva” that was causing the problem.  I contended that the plating was bad on the slide, and that it should not have failed after three weeks (10 hours of use).  After some wrangling, Steve said they would send me a new slide, and that I would need to send the defective slide back to them at my expense.  He also said that this would be the last effort their company would make to provide a working horn.

I received the new slide as promised about a week and a half later, and sent the defective slide back.  The new slide worked very smoothly, and an inspection of the slide before any use showed no pitting or deplating of the inner slide.  I was happily playing the horn at my orchestra practices for about a month, when I began to notice the scratchiness in the slide movement again.  I pulled the slide apart, and THIS slide was beginning to lose plating on one of the stockings as well.  I felt so disappointed.  This horn has a very nice sound, and all I wanted was a horn that I could use in the orchestra.  Here is a picture of the second slide stocking that deplated within a month of use:





Although I was not hopeful, I contacted Steve Di Lucca after the second slide plating failed.  Since the horn had a “Manufacturer’s Two Year Warranty”, I decided to try to contact the manufacturer directly to get the slide replaced.  Here was Steve’s reply to my inquiry:

WOW! What is going on? I've been selling this horn for over ten years and NEVER have I had a slide with this issue. OK, maybe the first one was blemished, but the second and now third slide? No way is this a result of manufacturing defect. There is something going one on your end that is causing this. Because it is a user issue, it is no longer eligible for the warranty. At this point we are finished. I am sorry but, I have bent over backwards to accommodate your requests.

The warranty is very clear on what is covered. Whatever you are doing is causing the issue, thus nullifies the warranty. We are the manufacturer and we deal with the warranty work so there is no other place to contact. You are past the return period. As you acknowledge in your email we have done all that we can for you. I am now out two slides which leave two horns without slides until next year when I get a new shipment.
I wish you luck and am sorry for issue.
Steve Di Lucca


We went back and forth by email a few more times, and I finally asked him for a refund on the horn.  He refused, and that was the end of our conversations.

Despite Steve’s assertion that “we are the manufacturer,” I know that this is a Chinese-made horn, and the Great Tunes does not make them in Idaho.  While I am grateful for the attempts that Steve and Great Tunes made to give me a playable horn, in the end, the manufacturing defects of this Chinese horn sabotaged their efforts.  I feel that as the US marketer for these horns, Great Tunes needs stand behind them even when they fail.  They did not satisfactorily resolve my issues, and I’m unfortunately left with a case full of shiny metal.

I am very disappointed in the company’s resolution of this matter, and hope that anyone considering a musical instrument purchase from Great Tunes Direct would consider my recent experience there.

Monday, December 5, 2011

Power to the People: How to Build a Plug and Play Grid Tie Solar Array

 
P1060193.tmb

Background:  In August 2006, we had a 6300 watt photovoltaic system installed on our roof through our state’s clean energy incentive program.  Our system consists of 36 Sharp NT-175U1 175 watt solar modules, and two Xantrex GT 3.0 inverters.  It makes about 7300 kWh per year.
 
In the winter of 2009-2010 our area got over 80 inches of total snowfall.  As a result, some of our solar modules were damaged by the snow.  The damaged modules were on the edge of the roof near the gutter, and we think that the heavy snow accumulations between the roof and the modules went through freeze/thaw cycles that most likely caused the aluminum frames on the two modules to bend.  Despite the damage, the modules were still electrically functional.  Here is a picture of one of  the damaged modules:
 
 
 P1010540.tmb             P1010539.tmb            
Bend in the PV module frame.
       
Sharp Solar Warranty Hassles:  As you can see, the frames bent at a hole at the midpoint of the module, pulling the aluminum frame away from the glass plate of the module.  When my solar contractor inspected the damage, they thought that three of the modules had bent frames.  Our contractor tried to get Sharp Solar to replace the modules, to no avail.  My contractor’s PV module supplier also tried to get Sharp Solar to replace the modules, to no avail.
 
The modules came with a 25 year warranty, so I personally contacted Sharp to see if the damage would be covered by their warranty.  Although Steven Yorita at Sharp Solar was very courteous, he stated that his superiors told him that the damage to the modules would not be covered under the warranty.  My contention was that the frames were not properly designed, and that there should have been a brace in the middle area to prevent the frame bending in that area due to stresses.  Sharp Solar did not agree with me, and refused to honor their warranty saying that the warranty did not cover damage due to snow and ice.  We negotiated for several months, and when it became clear that we reached an impasse in negotiations, Sharp Solar agreed to sell and ship me three new replacement modules for half price—around $350 per module plus shipping, and I could keep the old modules. 
 
In December 2010, before the first 2010-2011 snowfall, my solar contractor came to replace the modules.  While working on the roof, he found that only two of the modules were damaged, so I now had two damaged modules, and a new module left after the repairs, and I stored them in my garage for  the winter.
 
Here is a picture of the contractor switching out the damaged and new modules.
 
P1010541.tmb
The modules on the left were the snow damaged modules.  The module on the right was the new module.  Note that the new module came with a mid-frame brace at the exact point where the old modules deformed.
 
 
How to Deploy the Spare Modules?:  While the three 175 watt panels were stored in the garage, I thought about how to use the extra modules.  I came up with three ideas:
 
1.  I could mount the three modules on the roof of my sunroom, but that would entail putting racks on the sunroom roof, and drilling through my shingles.  We have had some difficulties with leakage from the lag screws that attach the racks onto my main roof for the 36 modules up there, so I was not too keen on penetrating another roof with lag screws. If I used this option, I would use Enphase microinverters, but that would require running a 240 line out to the sunroom from my breaker panel.  In the end, I rejected this option as too much work and too expensive.
 
2.  I thought about building a pergola over my concrete patio, and placing the modules on the pergola, using the microinverters.  This option would avoid drilling holes into my sunroom roof, but I would still have to build a structure, and supply a 240V AC circuit for the microinverters.  This was still a bit more work than I wanted to do.
 
3.  I could build a ground rack, and use the inverters found on eBay that invert the panels’ DC current to 120V AC and backfeed into existing household circuits.  I researched the experiences of people who had used these Chinese inverters, and found that several people had good experiences with the Sun G inverters.   I decided to go with this option.
 
Repairing the Damaged Module Aluminum Frames:  My first order of business was to repair the damaged frames on the two modules that came off the roof.  This was fairly simple.  I simply unscrewed each damaged frame piece (only one of the four frame sides was bent on each module), and placed it in the space between the slab and the bottom of my storage shed.  I lined up the bend with the edge of my shed, and pulled up on the frame piece, straightening it back into its original shape.  I actually bent it back a little too far so some tension would hold the rubber gasket on the module edge snugly in place.  I put the rubber gasket on the module back in place, and reattached the newly-straightened frame piece.  I also tested the modules in full sun, and they were still perfectly functional.
 
Inverter Selection:  A solar electric system consists of two basic components, the photovoltaic (PV) modules that create direct current (DC) electricity from the sun, and inverters that invert the DC to AC (alternating current).  In my net research, several people had remarked that the Sun G type inverters were somewhat inefficient, and that you should purchase an inverter rated at twice the watts you want to feed into the inverter.  For example, my three 175 watt modules would theoretically supply 525 watts (3 X 175) to an inverter, and some comments I read on the net suggested I would need a 1000 Watt inverter for maximum efficiency.   I found one particularly helpful study on the web that helped me to decide what size inverter to purchase:    http://www.youtube.com/watch?v=o9rWaqbOOMo.  In this YouTube video, sparktastic 1 showed that at full 500W power input, the Sun 500G inverter had about 82% efficiency.  Feeding the full 500 test watts into two Sun 500G inverters only slightly increased the efficiency to 87%. 
 
Seeing that my three modules had a zero percent efficiency sitting in the garage, I opted to purchase a Sun 600G inverter off of eBay for $161.00 (including shipping).  I would have 525 rated watts of panel power feeding a 600W rated inverter.  The DC output voltage of my Sharp 175s was about 44 Volts, so this inverter would accept the voltage from the modules.  To keep the inverter input voltage at 44 Volts, the modules would be wired in parallel so that the inverter input voltage would stay the same, and input DC amps would be additive.  The AC output of the inverter is 90 to 130 volts, and would match my house sunroom circuit voltage.  I planned to backfeed the inverter’s AC output into my house through an outdoor outlet on the back of my sunroom.  It is important to note that this inverter has anti-island protection which means it shuts down in the event of a power failure, and does not energize circuits in my house in the event of a power failure.  This feature protects utility workers who could be working nearby from unexpected exposures to electrical current.
 
One thing that did concern me about this inverter is that it is not UL or other recognized testing lab approved.  To deal with this risk, I decided to mount the inverter to the rack I would build for the modules so that if the inverter failed/burned/shorted, it would not catch my house on fire.  I also made sure that the inverter output current would backfeed through a GFCI (ground fault circuit interrupter) protected house circuit that supplies my outdoor outlets, and that the inverter output would not exceed the circuit breaker and GFCI rating for the house circuit.
 
As far as overloading the household circuits go, I calculated that the maximum current output of the inverter would only be about 3.5 amps AC.  (525 watts X .80 efficiency divided by 120 volts = 3.5 amps).  This output would not stress the 15 amp AC circuit that supplies the outdoor outlets.
 
Here are the specs and a picture of the inverter I bought:
 

Electrical Specifications:

Model

SUN-600G

Normal AC Output Power

540W

Maximum AC Output Power

600W

AC Output Voltage

220V/230V/240V

190V ~ 260V

110V/120V

90V ~ 130V

AC Output Frequency Range

46Hz ~ 65Hz

Total Harmonic Distortion(THD)

<5%

Power Factor

0.99

DC Input Voltage Range (Optional )

10.8V ~ 30V / 22V~60V

Peak Inverter Efficiency

92%

Standby Power consumption

<0.5W

Output Current Waveform

Pure Sine-wave

MPPT Function

Yes

Over Current Protection

Yes

Over Temperature Protection

Yes

Reverse Polarity Protection

Yes

Anti-Island Protection

Yes

Stackable

Yes

 

Mechanical Specifications:

Operating Temperature Range

-10 0C ~ 45 0C

N.W

3.6Kg

G.W

4.0Kg

Dimension

332mm*265mm*135mm


 

 Inverter picture
 
Designing the rack:  Once I received the inverter and repaired the bent frames on my modules, I built a rack to hold the modules.  One thing I wanted for the rack is the ability to seasonally change the angle of the modules to get maximum efficiency.  I found this great article that describes the optimal tilt angles for solar modules, depending on your latitude:  http://www.macslab.com/optsolar.html.
Our latitude is almost 40 degrees north, so I used the charts in this article to determine the three tilt angles I would need for seasonal changes.  Here is a chart I prepared for planning the rack based on our 40 degree north latitude:
 

 Module Tilt Angle (degrees)                                                 Dates

59.6

October 7 through March 5

36.9

March 5 through April 18

12.5

April 18 through August 24

36.9

August 24 through October 7

 

 
Building the Rack:  The entire unit has two parts:  a boxy support rack structure and a “tabletop” consisting of the three modules connected together by two 2X4s.  Given the large range of tilt from 12.5 to almost 60 degrees, I designed the rack to accommodate a prop rod that would provide all three tilt angles.  This meant that the support rack structure had to be at least 36 inches high to allow for the prop rod to work at all the angles.  I constructed the box frame out of pine 2 X 3s I got at Home Depot, and some 1X3 bed slats that I salvaged from someone’s trash.  I employed a variety of galvanized deck screws.  The frames were attached to 2 X 4s near the top and bottom of the modules using nuts and bolts with lock washers, and the three module tabletop unit was attached to the support frame using door hinges which would allow the three modules to tilt.  Here are several pictures of what ensued:
 
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Note the three PV module hinged “tabletop.”  The bottom supporting box rack was high enough so that a single prop rod could tilt the modules into all three angles. This is the winter configuration at 59.6 degrees.  Door hinges attach tabletop modules to the bottom support rack.
 
 
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Holes were drilled in the top of the supporting box frame and in the prop rod for each tilt angle—59.6, 36.9, and 12.5 degrees.  This picture shows the highest angle.  Carriage bolts with wing nuts allow the angle to be easily adjusted seasonally.
The unit was a bit top heavy on the hinge side, so I used ground stakes to anchor the unit into the ground in the back, and to provide electrical grounding for the modules and inverter.
 
 
How to set the tilt angle:  To drill the holes in the prop rods and top of the supporting box rack to get the right tilt angles, I used a handy device I got on eBay ($9.00) called an inclinometer.  These are usually used to align satellite dish angles, but they work well in solar applications too.  After the 3 module “tabletop” was attached to the bottom support rack using the door hinges, the supporting box frame was leveled, and I used temporary 2X4s to hold up the tabletop while I measured the angle with the inclinometer.  When the right tilt angle was achieved, I drilled a hole through both the prop rod and the support rack top bar (with the prop rod at right angles to the support rack top bar), repeating the process for each of the three tilt angles.
 
Here is a picture of the inclinometer in use:
 
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You can barely see where the module frame was bent after I repaired it.  The shed in the background provided the weight to lever up on the bent extruded aluminum module frame and straighten out the damage.  The inclinometer is reading about 60 degrees for the winter tilt setting.
 
 
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A 3 inch deck screw attached the prop rods to the 2X4 on the tabletop.  The box frame was leveled when I moved it to the yard using concrete block pavers from Home Depot.
 
Mounting the Inverter to the Support Box frame:  I wanted to protect the inverter from the elements because I was mounting it on the box frame and not the house.  I suppose the best way would be to put it inside an electrical box, but these inverters heat up when in use and I wanted some ventilation.  I decided to simply put the inverter inside an inverted polyethylene dishpan from K-Mart.  To mount the dishpan and inverter to the supporting box rack, I used a piece of 1X12 that I had in the garage.  Here is how the inverter was mounted:
 
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Inverter, exposed to air but snugly protected by the dishpan.  I drilled holes in the outer edges to keep water from collecting.
 
Making the Electrical Connections:  Because the original PV system on our roof was completed in 2006, all of the damaged PV modules had older MC3 connectors.  The new replacement modules from Sharp came with MC4 connectors.  My solar contractor had to cut off the MC3 connectors from the damaged modules and put them on the new modules.  I had them connect the MC4 connectors to the damaged modules positive and negative wires before they left.
 
To connect the three spare modules to my Sun 600G inverter, I decided to buy some new MC4 connectors so I could make connecting wires between the modules and the inverter.  A local solar supplier was very helpful and sold me 3 male MC4 connectors and 3 female MC4 connectors for a reasonable price (around $25).  I also got some 12 gauge multistrand wire, some DC tube fuses and holders, and some ring connectors from McMaster Carr.   My connector wires consisted of an MC4 connector, a run of wire, a soldered fuse holder and fuse, a run of wire, and a soldered ring connector to fit over the negative or positive post on the inverter.  Six of these connector wires were constructed, 3 with male MC4 connections, and 3 with female MC4 connections.  I did not buy the expensive MC4 connector tool, but soldered all the MC4 connections to the 12 gauge stranded wires.  I had read online that it was a good idea to place DC fuses between the inverter and the modules, so each positive connector wire got a properly rated DC fuse (they were rated at 125DC volts, 10 amps).  Because I wanted all of the connections to be soldered, I used the little plastic fuse holders for tube fuses.  That didn’t work out too well (the plastic sleeves wouldn’t fit over the soldered connection, so the whole fuse assembly was just encased in layers of 3M electrical tape for insulation.
 
A Word About Fuses:  There are two excellent papers by John Wiles at New Mexico State University that I consulted on the confusing topic of fuses in PV systems.  These papers are "Focusing on Fuses"  at http://www.nmsu.edu/~tdi/pdf-resources/cc67.pdf and "To Fuse or Not to Fuse" at  http://homepower.com/article/?file=HP125_pg106_CodeCorner.  The first article helped me to understand how fuses are rated, and how to select the correct fuse for a PV system.  The second article focuses on the question of whether to fuse or not.  After reading the second article I determined that I needed to add a fuse to each of the positive leads on the PV modules.  Fusing is necessary in a parallel system where the combined output of the other  modules (or strings) in parallel could backfeed into a failed module.  Here is an explanation of the process I used as described in the article for making the decision of whether to fuse or not to fuse, and how to select the right-sized fuse. 
 
From reading the labels on the back of my Sharp NT-175U1 PV modules, I learned that the short circuit current (Isc) for the modules is 5.40 amps.   The label also says that the fuse rating on the modules is 10 A.  Since I have three modules in parallel, if one of the modules fails, the remaining two modules wired in parallel could theoretically force 13.5 amps (5.40 amps X 1.25 (NEC's worst case max output)  X 2 modules) into the failed module.  Since 13.5 amps exceeds the 10 amp fuse rating on the module, each of the modules needs at least a fuse rated 1.56 times the Isc (8.4 amps), but no higher than 10 amps. In my case I would need a DC rated fuse of 8.4 to 10 amps.    To meet this requirement, I chose a fast blow, Bussmann ceramic DC fuse rated at 10 amps, 125V  DC from McMaster Carr  (Part # 71385K34).  Here is a link to the fuse I got from McMaster Carr.  http://www.mcmaster.com/#catalog/118/922/=gh3rxn
 
It should be noted that not all parallel systems need fuses.  In my next project I’ll be feeding two parallel-wired Evergreen 220 watt panels into a Sun 600G inverter.  The labels on the back of these panels state that the short circuit current is 8.22 amps, and the fuse rating on the module is 15 amps.  Since there is only one module that could backfeed into the other in a fault situation, the maximum backfeed would be 8.22 amps X 1.25, or 10.27 amps.  Since this value is less than the 15 amp fuse rating on the panel, I don’t need to add fuses to the positive leads of this array.
 
In the end, the electrical setup looked like this:
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Fuses were encased in electrical tape.  (Not so great)
The inverter output wire that came with the inverter was a standard three pronged power cord.  I connected this to a 12 gauge wire, 25 foot long extension cord and plugged it into an outdoor outlet.   There were three sets of positive and negative leads with MC4 connectors coming from the modules. For parallel wiring, each module’s positive output went to the positive post on the inverter, and each negative output to the negative post on the inverter.
 
Here is a view of the high-tech inverter protection and assembly from the front of the unit:

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How well does it work?   Before turning on the unit I oriented the modules to solar south.  The magnetic declination in our area is about minus 13 degrees, so the unit was aimed at 13 degrees west of compass south.  Find your magnetic declination here:  http://magnetic-declination.com/.    Since it was already mid-October, I raised the module tilt to its winter setting of 59.6 degrees.   I connected the unit for the first time in mid-October 2011.  Using my Kill-A-Watt meter, here was the output I got on a nice clear day:
 
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Using my Kill-A-Watt meter, I actually saw the output get up to 397 watts AC at one point.  This would put the total efficiency of the unit at 76%. (397W/525W).  I’m pretty happy with the results of my project.   The unit should produce about 700 kilowatt hours per year, or about 8% of our yearly electricity use.  I have not seen the AC current output go above 3.5 amps.
 
What I learned:  If I did this over, I would not have built the rack so high.  I built it three feet high so I could use one set of prop rods.  If I did this again, it would be half the height, and I’d simply have three different sets of prop rods for each tilt angle.  This unit is kind of high (around 6 feet) when the modules are tilted up at their winter angle.
 
Module tilt angle makes a big difference.  I tilted the modules at several angles in the sunlight, and having the correct angle at the right season makes a significant difference in output.
 
I would figure out a different way to handle the tube fuses in my connector lines.  What I did with electrical tape works fine, but is not very elegant.
 
I would use a clear dishpan/storage container to protect the inverter. The inverter has indicator lights to show it is working.  There are three green LEDs that light up in sequence from left to right.  The faster they move, the more AC output from the inverter.  There is also a red LED to show that the unit is not receiving grid electricity, and has shut off to prevent islanding.  The use of a clear storage container allows easier monitoring of the LED status lights.
 
I wish there were some low-cost 120 volt output inverters that were UL approved, and that were made in the USA.  The inverter I used is made by the Ningbo Hi-Tech Park Sunshine Technology, Co. Ltd. in Ningbo, China.  The inverter carries a CE certification for electromagnetic interference.  Here is a link to the company’s website:  http://www.chinesegrid.com/I’ll be interested to see how long the Ningbo Sun-600G inverter lasts.  
 
Not counting the solar PV module costs, I spent about $260 on the inverter, wood, screws, wires, fuses, MC4 connectors, concrete pavers, plastic dishpan, ring connectors, and hinges.  Our local electricity rate is about $0.20 per kWh, so at an annual output of 700 kWh for this unit, it will take about 1.9 years to recoup my materials costs.  Of course, if you have to buy the modules the payback would be a lot longer.  In my case, the modules were gathering dust in the garage.  
 
I calculated the 700 kWh output using the PV Watts solar calculator:  http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/.  The basic PVWatts calculation for a .525 kW system in our area gives an anticipated output of 665 kWh per year.  The article above that discusses changing the tilt of the modules says that changing the tilt angle seasonally (4 times a year) increases the output by about 5%.  Thus the anticipated output of this system is approximately 698 kWh (rounded up to 700 kWh).
 
Costs aside, this three module project prevents 1000 pounds of carbon dioxide per year from going into the atmosphere (1.428 pounds per kWh in the RFCE region from EPA’s eGrid chart): http://www.epa.gov/cleanenergy/documents/egridzips/eGRID2010V1_1_year07_SummaryTables.pdf).
 
I wanted to write up this project so you can see that it is really not all that difficult to do a small scale solar project.  As the prices of PV modules drop (they dropped 40% in 2010-2011), it will become even more affordable to produce some or all of the electricity you use from solar.
 
More Information:   I recently ran across this company in Great Britain that commercially sells the same type of plug and play system:  http://solar-power-station.co.uk/.  Click on the specifications for the systems they are selling, and you’ll see that they too are clearly using the Ningbo Sun G inverters.    I wonder when this solar power station will come to the US? 
 
The Brits are selling their 200 watt system for 795 GBP ($1270).  In March 2012 I am able to find solar modules in the US for about $0.80 a watt.   The system I made as described here in my blog is 525 watts.  Using a cost of $0.80 a watt for the modules ($420) and $260 for inverter and materials,  the cost of my system would be $680.  At a retail electric cost of $0.20 a kWh in my area,  my system’s payback time assuming an annual output of 700 kWh is about 5 years—without rebates, REC sales, or tax incentives.

November 5, 2012 Update:  This DIY solar plug and play project has been operating without problems for over one year now (October 2011 through November 5, 2012).  It has reliably produced electricity, and it operated well through a very hot summer.  I have been impressed with the performance of the Sun 600G inverter so far.  The only change I’ve made to the project is that I shortened the rack height in half to make it more stable and less obtrusive.  Here is a picture of the system after I cut the rack height down. The modules are at their summer tilt angle of 12 degrees in this picture: