Sunday, 21 April 2013

Solar PV for your Home - Part II

Solar PV in the Hamilton Trenches

The dawn of a new season ...

So, I'm sure, every one wants to know, "How is the 4 kW two-branch, micro-inverter-based, solar PV system mounted at two different roof pitches in a densely housed neighbourhood performing?"

This system was connected to the grid on December 19th, 2012 and, since about the second week of March, it's electrical generation has been increasing dramatically for several reasons about which I will further elaborate.

The Enphase micro-inverters are connected to the Envoy monitoring system which broadcasts system performance over the internet.  Enphase is continually improving the presentation of these systems and their performance through their online Enlighten Portal. Check out this systems performance through the portal and/or review its daily power & energy timelapse plots until I return ...

Discussion on what is refered to as 'balance of system (BOS)', will soon be posted, including  combiner box(es), disconnect(s), meter bas(es), etc.

To read about system performance challenges due to the weather and the design of the system and revenues generated through electricity produced by the system under Feed-in Tariff contract with the Ontario Power Authority visit our Facebook page (

Saturday, 23 June 2012

Solar PV for your Home!

Solar PV in the Hamilton Trenches

In the beginning ...

On Friday, June 22, 2012 I received an email from the Ontario Power Authority (OPA) congratulating me on having been approved for a solar PV system installation on my home.

I applied in January 2011, over a year and a half ago, but didn't contact my Local Distribution Company (LDC) until April 2011. I also didn't push or follow up during any stage of the process ... just to experience how it might pan out.

In October 2011, concern over the outcome of the provincial election resulted in Feed-in Tariff Program uncertainty, which delayed the scheduled review of the program. Since then, the program has been under review with no updates other that the Review Report (issued in late March 2012) and draft rules and regulations (posted in early April 2012).

Though nothing has been formally announced and neither the online FIT nor microFIT web-based portal appear 'open for business', I assume that I am not the only one to have recently received a Conditional microFIT Contract from the OPA.

I plan to document the entire process through this blog!

July 12, 2012 UPDATE

OPA Official Announcement: "We are pleased to advise that the window for microFIT applications is now open."  Here's the link to the microFIT portal for new-comers to the program to Register and then submit an application

Don't hesitate to contact me if you need help with the application process and/or want to know more about the Feed-in Tariff Program or other ways through which you can become an electricity generator.  I can also help in estimating the potential generation capacity (i.e., kWh/mn) and in developing the design of a Solar PV system installed on your home or business.  I plan to complete the study on my own home next week and will post pictures & findings.

Special Note
Those who submitted an application for a microFIT project after September 1, 2011, will need to resubmit their application according to the instructions posted here

December 1, 2012 UPDATE

After the big move to Nova Scotia got delayed, I decided to go ahead with my solar PV MicroFIT project!!

The system will be a roof-mounted solar PV array on a 1100 square foot, 1.5 storey house in a densely housed neighbourhood in Central Hamilton ON Canada.  It's nameplate will be 4.24 kW [DC] ~ 3.44 kW [AC].  It will be comprised of two (2) 8 module/micro-inverter AC branches, center-fed into a roof-mounted combiner box.  The solar PV modules will be Silfab 265W monocrystaline and the system will use Enphase M215 micro-inverters.

Technical details & pictures to follow ...

December 17, 2012 UPDATE

So this is the site.  The aerial image on left is of the house (yellow box) and surrounding neighbourhood.  The image on the right illustrates the south-east facing roof surfaces of the house.  The south-west facing portion of the roof at the front of the house was considered to be excessively shaded by the tree in front of the neighbour's house to the south.

Site Assessment

Designing a solar PV system is an iterative process, starting with the following preliminary checks:
  1. Roof Surface Orientation
    • Available roof surface(s) should face S, SE, or SW.  While due east - or west - oriented surfaces will also capture solar irradiation, they will produce considerably less. [See Tools section below to explore the effects of both roof orientation & pitch on incident solar irradiation]
  2. Roof Pitch
    • Available roof surfaces should (ideally) be at a pitch of the latitude of the location +/- 15°. [See Tools section below to explore the effects of both roof orientation & pitch on incident solar irradiation]
  3. Roofing Material Condition
    • Consider replacing the roofing material on a roof  if it is comprised of asphalt shingles > 10 years old, prior to installing any roof-mounted equipment.
  4. Structural Assessment
    • Consider contracting a structural engineering firm to confirm the load bearing capability of the roof rafters or trusses.
  5. Shading Analysis
    • Identify roof areas where shading will be excessively detrimental i.e., we are seeking unshaded solar access from 9AM - 3AM throughout the year. [See Tools section below to obtain a sun path chart for a location based on it's Lat/Long coordinates (see Step 2.) and other shade analysis hardware & software]
  6. System Size [kW] & Generation [kWh]
    • Evaluate roof area & dimensions vs. solar module size (length & width) vs. solar module mounting orientation (i.e., landscape vs. portrait).  
      • There are numerous solar modules on the market of varying nameplate (i.e., Watts [W] per module) and size (i.e., length, width, and thickness).  
      • Standard modules for generating electricity for commercial buildings, small businesses, houses, etc. typically range in nameplate from 200+ W to 300+ W.  
      • The larger nameplate modules are usually similar in width (e.g., ~ 39") but greater in length (e.g., ~ 78" vs. 65").  
    • The nameplate of the solar PV system (i.e., a collection of solar modules) that can fit on the designated roof surface(s) is especially important for those designing an Off-Grid system.  
      • Such a system needs to be designed to meet electrical consumption [kWh/day].  This electrical consumption figure needs to be converted into an Ah/day consumption amount (For example: Given that Volts [V] x Amps [A] = Watts [W], kWh/day times 1000 W/kW divided by system voltage of 120 V = Ah/day).  From there, a battery bank needs to be configured that can meet the Ah/day consumption with 'X' days of back-up, and a solar PV system needs to be designed that can charge such a battery bank.  
      • Off-grid system design should start with an Energy Audit to identify sources of energy inefficiency and quantify the electricity actually being consumed.  
      • An Energy Audit will save money by reducing demand through identifying ways to improve building envelope efficiencies, which impact heating and cooling electrical demands, identifying inefficient appliances (e.g. furnace, A/C, fridge, freezer, stove, lighting, etc.), and educating on energy efficient practices, allowing for the design and installation of a 'right-sized' system that can actually meet the 'true' electrical demand.
    • For Feed-in Tariff and/or Net-Metered systems, generation capacity will assist in determining the economic feasibility of the project, should payback and/or ROI be of importance during this era of electrical supply instability and utility industry $/kWh price - point uncertainty and historical increases.
  7. System Configuration: 
    • Using the findings from Step 6., truss and/or rafter locations vs. allowable mounting rail cantilever (as recommended by rail manufacturers), and solar module mounting point dimensions, fine tune the design of the system to determine number and length of rails required and the actual number of solar modules that can be mounted.
      • There are a myriad of roof-mount and ground-mount racking system manufacturers. DIYers can start their search through the Canadian Solar Industries Association (CanSIA), while there are many other manufacturers who are not necessarily CanSIA members.
      • Alternatively, consider contacting a local system installation company as identified through CanSIA, or, if you are located in the Hamilton area, consider contacting EcoDomus Consulting
  • Sunpath Charts can be obtained through the University of Oregon's online SunChartProgram

  • Hardware for capturing shadow casting objects & software for calculating shading impact:

 System Design
Completing the Site Assessment portion of the process should have identified the most appropriate solar modules and associated racking system.  But what about inverter(s)?

To decide between micro-inverters [M] (i.e., 1 inverter per solar module) and string inverter(s) [S] (i.e., 1 inverter per group of solar modules), the following should be considered:
    • Is  there shading in some areas and not others? [M]
    • Are solar modules being mounted on multiple roof surfaces at different orientations and/or pitches? [M]
    • Are a mix of different nameplate / manufacturer solar modules being used within the same system? [M]
    • Will the system be expanded over time? [M]
    • Is the system a demonstration system with interest in observing per solar module - level monitoring? [M]
    • Will the system be off-grid? [S]
String inverters [S] are considered ideal for homogeneous systems (i.e., pitch & orientation throughout the entire array is the same and solar modules are of the same make & model) not subjected to shading, from an installation labour, cost, and maintenance standpoint.  There is some discussion around micro-inverters applications being more efficient, especially when the solar array is a long distance away from the load due to direct current (DC)-related line loss reduction.

At the time of this posting, micro-inverters on the Ontario market are not able to operate in off-grid applications. They are designed to be grid-connect compliant (i.e., they need to monitor the grid, which requires them to draw electricity from the grid in order to operate).  This power consumption is minimal and required for the operation of the safety-related feature of grid-tied inverters.  Grid-tied inverters are required to shut down when the electrical grid to which they are connected becomes disabled so that electricity is not being fed in while the system operators are working on repairs.

As such, these micro-inverters cannot easily, currently, be used for off-grid applications.  There are probably ways to use them but converting solar module direct current (DC) electricity to the alternating current (AC) required to feed into the electrical grid using an inverter only to need to convert back to DC in order to charge the battery bank is a waste of energy due to the inherent inefficiencies of the DC-AC-DC conversion process.

For this demonstrator site with same orientation, but different pitch roof sections and shading issues, micro-inverters were selected.

So here is the layout for the two roof surfaces:

Main Roof 2.1 kW branch

 Dormer Roof 2.1 kW Branch

Keep tuned for more ...

December 19, 2012 UPDATE

It took only eight (8) days from system design to receipt of OPA “Connection Completion” message!

The site assessment & system design were conducted by Ruth Cooper of EcoDomus Consulting.  The racking, micro-inverters, and solar PV modules were supplied by Sentinel Solar.  The Master Installer with micro-inverter expertise was Mihai Roibu (Rombro Solar Energy Inc.) assisted by Ruth.  The Master Electrician was Dario Pilot of Current Solutions.  The ESA Inspector was Mike Szabo and the utility company, otherwise known as a Local Distribution Company (LDC), contact was Vito Genovese of Horizon Utilities (HU) who made this all possible in such a short time frame.  HU's Metering Department contact, Dominique, and the disconnect / reconnect crew were fabulous!

Check into this blog soon for a continuation of this post to be title "Solar PV for your Home - Part II" within which we will cover other lessor known parts of the system i.e., combiner box(es), disconnect(s), meter bas(es), etc.  We will also talk about system performance challenges due to the weather and the design of the system.

Thursday, 14 June 2012

Here's to Crazy Cat People

Sharing the Bathroom with Felines

So there I was, doing my usual reading up on the renewable energy industry magazines, industry news articles, and catching up on email ... I know, my idea of fun is possible dimented.  Needing cream for my coffee, I hit the local convenience store and found an article in the Hamilton Spec that caught my eye; it was an article about a TV persona and amazing DIYer living right here in the Greater Hamilton Area.

Eagerly seeking the next procrastinatory adventure so as not to have to focus on the finicky details of numerous projects I have underway, I thought to check her out through her Blog: The Art of Doing Stuff by Karen Bertelsen. Forgive me for not knowing of her.  I'm relatively new to the Hamilton scene and don't subscribe to cable TV.

Don't get me wrong, I have a TV which I purchased from the Restore for $15!  This allows me to watch my old VHS movies.  Neither my laptop nor recently purchased iPhone seem to be able to handle that technology?

Further investigation lead me to another amazing Blogger who commented on Karen's blog about pet food dishes, which then lead me to the post about "How to Toilet Train Your Cat" by Karen.  I call these distractionary dalliances "creative procrastination" vs. time wasters!

So there are women who have cats as pets and they are typically, by default, called 'crazy cat lady'.  I propose that we reserve this ostentatious title for those who successfully toilet train their cats!  Through her Blog, she shares the entire process in great detail and gives tips on how to avoid failure or feline trauma.

I've been in the company of Siamese cats most of my life and often thought about their 'smarts' and considered attempting toilet training, but was always in a career position that took me out of the house for long hours or days on road trips, so couldn't really start a decent program. I have tried every kind of litter known to man in an attempt to reduce waste and weight of feline fecal matter destined for the landfill.

To motivate those dabbling with other solutions to consider the toilet training program, I share the following experiences I've had trying alternative litters.

The Lowdown on Kitty Litter

Clay-based Clumping Litter is bad for the cats' respiratory system, as well as their human companions' and weighs more than the waste management will consider picking up if you have a multi-cat household.

I tried breaking my 1 bag into 2 bags, using the kitty litter bags themselves as bags, only to find that this now exceeds the 1 bag limit (or so it seems, as they only take 1).

Flushable Litter (most) must be administered to the toilet by the tablespoon for low flush toilet-acceptance.  This is, obviously, quite time consuming and not all that enjoyable.

Biodegradable, Grain (corn/wheat) - based Litter is seriously hydrophilic and clumps into concrete-like football-sized offerings (especially the Swheat Scoop) that need to be shovelled vs. scooped and to be chopped up into small pieces before they can be flushed.  Given how light it is, it also tracks all over the house; I actually find it under the covers at the foot of my bed when I'm changing the sheets!!  The upside is that it smells yeasty, like bread :)  Once again, though mildly amusing - especially when people ask why there is a garden shovel next to the toilet, kitty litter box cleaning remains time consuming and whole house litter sweep-up tedious at best.

Wood Pellet / Shavings / Newspaper - based Litter doesn't really clump, results in the house smelling like amonia, and isn't really flushable unless you want to feed the toilet in tablespoon fulls.

Faced with the fact that the majority of the 1/4 bag of garbage I put out on the curb is furry feline fecal matter, I started thinking that there must be a solution. Would you believe that with 3 cats (one was an accident - left behind by a pregnant housemate) my 1/4 bag of garbage weighs too much for the city's waste management crew to take away!!

I now find myself considering weighing in at the local transfer station, but the minimum charge of $8 would suggest that this solution is not a financially viable option let alone an environmentally sustainable one!


The Toilet Training Project

So ... the only sustainable, viable solution is to toilet train the feline herd!  My feline family consists of: Suki - an 10-month old Applehead Seal Point Siamese, Nala - a horrifically shy 3 year old Grey Tabby, and Simba - my 15 year old indoor/outdoor Champaign Tabby. P.S. Nala was named by the housemate who didn't know that I had a Simba .. too funny :)

I plan to start the program early next week and report back on anything of value and/or significance I experience :)  Hoping my experience will lend findings of assistance to other novice feline toilet trainers.

Wish me luck!

July 22, 2012 UPDATE

After a week long process of relocating the litter box from the ground floor mudroom to the upstairs bathroom, I began the process of slowly elevating the litter box to the height of the toilet rim.  I learned the hard way that it is imperative that the elevation platform be stable regardless of angle of litter box access.  Since I've always had a roof for my litter boxes, I assumed that the kitties would enter from the front short edge.  Once I removed this roof, to facilitate jumping, I discovered that they were jumping in from the side.  Unfortunately, the printer paper bundles I was using to incrementally raise the height of the box provided too narrow and unstable a base and the litter box was capsized by a member of the study group late last week! 

While this made a mess, no one seems to have been scared by the event except me.  I have since revised the platform and now use small shipping crates I collected from Plan B, a Flamborough Ontario-based organic CSA farm - Thanks Alvaro!

The top edge of the litter box is now roughly 2"-3" below the rim of the toilet.

Since my toilet rim is higher off the ground than a standard toilet and my litter box is quite deep, I may switch to a shallower litter box before I raise it again.  Simba is getting on in age and the Nala is a bit too much of a furry fatso to be much of a high jumper.  But I have great faith in 10-month old Suki.  All three cats religiously drink out of the toilet so I know that they can get up there.  The question is, "Will they jump up there to access the litter box?"  And, eventually, "Will they consider doing there 'business' in a human toilet vs. a litter box?"

I sign off for now and leave you with pictures of the stars of the experiment who are, from left to right (in order of age): Simba, Nala, and Suki.

February 4, 2013 - Belated UPDATE

Sorry for the delay in posting an update on the status of this complex project.  The experiment, unfortunately, actually came to an end mid - August :(  I sincerely thanked the participants in this experiment, especially considering that they really weren't asked for their consent; Simba, Nala & Suki were extraordinary in their own individual ways throughout this undertaking and Suki - own her own - may have succeeded.

Unfortunately, the end result was not quite what I had in mind and we have had to revert back to litter boxes at ground level and litter.  Mind you, it could have been worse - the felines may have decided that if they were expected to use a human toilet, I should now be forced to use the litter box!

The project was cancelled for 3 main reasons:
  • Simba, the indoor/outdoor cat, started to take great interest in adding organic matter to my garden;
  • Nala, the semi outdoor / shy cat did so as well and, as a 'furry fatso', decided that peeing on the couch was easier than leaping up the Eiffle tower of a toilet and/or trying to get outside; and
  • Suki, the indoor cat, got scared by the back-splash created by the 'right height' low flush toilet; at times, I'm even scared by it - it's almost a 1 foot drop from the seat to the top of the water level.
At the end, I would like remind us all that cat's instinctively want to bury their waste, unless they are Tom cats in heat, and that most cats are not all that fond of water.

While it might be a nifty party trick to show people your cats doing their business in the toilet, I've decided that it's almost cruelly inappropriate to even consider training them to so do, given that it goes against their instinctual behaviour and dislike of water.

Alternative Solution 

Composting!!  Green Venture in Hamilton holds regular workshops on how this can be done with dog waste and the work shops quickly fill to capacity. I am sure that the same can be done with kitty waste.  I promise to report back :)

I close by highlighting again the amazing subjects of the project, who are (from left to right, based on head position): Suki, Nala, and Simba.  They rock my world!

Sunday, 10 June 2012

"Time" The Most Finite of Non Renewable Resources

In the midst of all the global concern about and emphasis on decreasing our dependence on non-renewable resources involving everything from materials we choose to purchase and sources of energy generation we choose to advocate through to the foods we choose to buy/eat and modes of transportation we choose to take, we have lost sight of a very important non-renewable resource ...


I intentional repeat "we choose" to draw attention to the fact that the choice has been left up to us and that often choosing wisely in support of non-dependence on non-renewables and seeking a sustainable way of life takes time; it takes time to research the materials, products, and the service providers/companies.  It takes time to ask the questions that need to be asked.  It sometimes actually takes time to conduct research in support of figuring out how to do the right thing e.g., how do I dispose of construction waste, empty paint cans, electronic equipment, etc.  And, quite often, 

"it seems to cost more to make the 'right' choice".

Why is it that "time is money" unless it's your time?  

How much time are we collectively forced to waste?  I list the following as possible time wasters:
  • Commuting
o    we can't afford to live in the city wherein the company has chosen to locate
o    the company insists on standard hours
o    the company hasn't figured out resource management which would allow for telecommuting

I am convinced that if costs associated with commuting to work i.e., transportation + time were pushed back onto the employer through legislation, they would rather give us a raise than bear the costs.  I am also quite sure that the corporations' salary -structure take advantage of the fact that we don't live in Toronto.  This justifies paying us less based on the living expense where we live.  There was a time during which my commute time (based on % of work time*salary rate) + the associated transportation costs actually amounted to almost 10% of my salary.
  •  Waiting:
o    in traffic, due to poorly planned infrastructure and economic development initiatives
o    in doctors' offices – can't offer a logical reason for this one
o    in line at stores who are experimenting with self-checkout systems
  • Recycling:
o    sorting the unnecessary packaging, we never wanted to begin with, into the right bins
o    figuring out how to dispose of things the system won't accept
  •  Job Seeking / Working
o    I can't even imagine how many hours worth of valuable human resources are wasted seeking jobs during this era of key word resume scanning, social media overload, and job scarcity.
 o    Worse yet, I wonder how many people are 'under employed' just to pay the bills.  Surely, we can devise a better system than this?  Waste of human capital should be seen as a bigger problem than waste of $'s.
  • Bureaucracy:
o    Financial: co-op banks vs. public, mortgage companies vs. brokers, insurance, personal banking, investment / savings, taxes, pension plans, etc.
o    Public Services: public vs. private utilities and their services for electricity, gas, water, landline, cell phone, PDA, internet, TV.
o    Political: it seems as though every few months we are being asked to care about yet again another municipal bi-election, mayoral race, provincial or federal election.  In the grand scheme of things, I've never found the out outcome of any of these events to really make that much of a difference to my life.  While the time I think I should spend investigating individuals & party platforms is enormous.

All we really need is financial security, light, climate control (heating/cooling), electricity for our gadgets (AC & DC), and access to communication, interaction, and entertainment (voice communication, internet, messaging/emails, and movies).  If I were to approach you and say, "I will take care of all of this for you and monitor your habits to fine tune the service accordingly", I think that you would say, "Great".  The daily pestering from the myriad of individual service providers is just too much.

In support of a sustainable future, I suggest that much of this should really be offered as a service vs. a commodity.  As a commodity, think about $/min, $/GB, $/kWh, $/m3, etc. there is no incentive on the part of the provider to encourage you to become more efficient, no incentive for providers of products or ancillary services to improve, unless mandated (as it currently is through the Ministry of Energy for electrical appliances in terms of kWh consumption).  If we were to talk "lighting service", with all costs going back to the service provider, I bet you would quickly see motion detection based lighting with dimmer capabilities, LEDs, solar tubes, and houses designed to take advantage of natural lighting, etc. being mandated through the building codes and electrical standards.  But, I digress ...

Where any of us find TIME for family, hobbies & interests, and/or community involvement on top of our jobs and/or studies completely astounds me.

I really encourage us all to collectively / individually start pushing back on many of these fronts.

TIME is our PERSONAL non-renewable resource!

Why are we allowing others to mine it in so many unscrupulous and wasteful ways?

Take Your Stand

Demand the ability to telecommute at least 1 day a week.  You wouldn't believe how great you'll feel and how much more productive you'll probably be.  Or discuss shifting your hours so that you are commuting outside of the "hwy parking hour" window.  Even consider, if appropriate, offering to set up a branch office.  Expect/demand more from your employer.  At this day and age all companies are saying, "Our strength is our people."  Well, PEOPLE, speak up to improve your work environment; too many hours are spent there to ignore.  I recently read that OPower has days during which employees can bring their dogs to work!  How cool is that!

Choose to buy products with less packaging; comment, as appropriate, about packaging when it seems unavoidable.

Mention to those that make you wait that you're time costs X$/hr i.e. doctors, suggest to store managers that we need jobs and that auto-tellers are making the situation worse and wasting your time, etc.

I would advocate contacting your local MP, but it really depends on so many things. It's up to you on this one.

Stop buying in to the telemarketers offering you better rates for pretty much any utility/service; they are all about the same in the long run unless $20/mn is going to bankrupt you in the short term.  Request more inclusive, simpler bundlings.  Request services i.e., lighting vs. kWh of electron delivery :) Where there is a demand there will eventually be a service provider!  Maybe it will even be you & your company that head down this path.  I will happily be your first customer!

I propose that we try to live in a locally-focused, sustainable, supportive manner with our neighbours, neighbourhood businesses, and local farmers (markets).  Self-sufficiency at a community level is the key.  If we have all we need in terms of social engagement, food, clothing and shelter and the services required to sustain and maintain these amenities within our own community, we are invincible!! 

If you are overwhelmed by the call for activism, focus on your community or city and the aspects of it you would like to improve.

Focus on sustainable, local community / regional self-sufficiency

To engage with likeminded people in your area check out the local/global Transition Movement to support the efforts underway in your community.

Don't let anyone else mine it.  Use it wisely!

Sunday, 6 May 2012

The Historical cycle of the AC/DC Battle

How history repeats itself with no one being the wiser.

Back in the beginning, line losses resulting from low voltage Direct Current (DC) generation being transmitted over long distances and disinterest in building distributed generation infrastructure resulted in the development of the infrastructure we have today i.e., the Alternating Current (AC) electricity grid.  Without going into technical detail, AC is what comes out of the plugs in buildings, while DC is what comes out of batteries, including your car battery.
Over a century later, many countries are pursuing the development of distributed generation infrastructure based on renewable fuel sources.  Some of these fuel sources e.g., solar energy through solar PV technology, produce DC.  For countries with an AC-based electrical grid and an AC dependent appliance infrastructure in place, this DC electricity needs to be convert to AC for introduction into the existing grid.

Unfortunately, most of our 'gadgets', including cell phones, PDAs, laptops, PCs, Monitors, LCDs, Printers, etc. operate on DC.  For those not well versed in AC/DC outside of the Rock band: Any device that has a power cord that includes a box-like device, is a DC device.  The heat you feel when you touch the box-like section is an indication of how inefficient AC to DC conversion actually is.  Heat = wasted electrical energy.

So now we are building locally-based, distributed generation stations that won't need to transmit electricity over great distances.  But, instead of line losses, we are now hampered by conversion losses since we are generating DC, converting it to AC, only to convert it back to DC.  I suggest that we consider separate, co-existing, AC on-grid and DC off-grid development.
Are we witnessing the rebirth of the DC era?  Perhaps losses incurred through DC/AC/DC conversion are equivalent to the line losses once feared if we had chosen a DC-based system?

But the bigger challenge probably lies in the fact that we all have numerous AC powered appliances and tools.  While fridges, stoves, and other appliances exist in the DC world for use by mobile home and boat dwellers, I have yet to hear about the mobile home version of acompound mitre saw.  But, then again, I haven't researched this yet ;)

And so the AC/DC battle wages on.