The emergence of the EV market and its battery technology are certainly exciting.  As the number of EVs increases, so does the awareness of energy independence. For many enthusiasts DIY solar is on the rise.  What if you could pay $4000 for the life energy of your new EV and all your EVs to follow for the next 25 years? Would you? So what is involved? What size system do you need? What will it cost? If you are looking for a system to power your new or future EV, a 2 KWh system is a good start for the 15,000 mile per year driver.  So where do you start? The first step is the paperwork.


You will need to

  • Get an electrical permit;
  • File an application with your electrical utility;
  • File with your state utility commission;
  • Apply to be a power generator with your state generator provider;
  • Know your state tax credit;
  • Contact your home owner’s insurance provider.
Each state has its own tax credit and options for becoming an alternative energy generator. You may be inclined to build a photovoltaic system large enough to power all of your electrical needs, when in fact the best sized system may be limited by your “in state” generator contracts. A common sized system is 5kWh.

sp 4

A good place to start is with your utility company.  They will provide you with the necessary applications to meter your system as well as directing you to the organizations responsible for providing credits for the power you sell. That’s right, in many areas, you will be able to sell your excess electricity for equal to or even double your purchase rate.  The most popular system is referred to as a “grid-tied” system. This system functions without expensive batteries and is plugged directly into a double pole breaker in your main supply.  The grid-tied system uses or sells electricity by day and buys electricity by night.  What are the components and their costs?

You will need:

  • Adequate sized solar panels;
  • String or micro inverters;
  • Monitoring system (optional);
  • Mounting racks , clamps and possible posts if ground mounted;
  • Grounding rods and connecting wire;
  • Disconnect switch at your meter and your array if ground mounted.

A common size for each solar panel is around 250-270 watts.  The price of a quality panel in 2013 is around $200-$300 per panel. Hence, if we are building the 2kWh system for your EV, you will be looking at eight panels for around $1600-$2400.

For the DIY system I chose the Enpahse M215 micro inverter for my system.  You will need one micro inverter for each panel. The panels are configured with either a Tyco or MC4 connector. You must specify the same connector when ordering.  Such an inverter will cost about $180 per inverter or $1440 for your 2kWh EV system. With this brand, you will also need a special cable to chain the inverters into one branch circuit for around $100.

There are many cool monitoring systems that let you view your daily energy production.  The Enphase Envoy Management system is optional and around $475

Mark's DIY Solar Array

Mark's DIY Solar Array

You must decide whether your will have a roof or ground mount system.  The roof mount is the easiest and most economical. Your 2kWh roof mount can be purchased for around $400. I chose a ground mount system for a better southern angle. The ideal angle is from southeast to due south.  Theoretically, true south will yield the best production, but the lack of morning heat in some areas will make a southeast orientation an equally good angle.  Ironically I recycled my ground brackets from retired utility electrical towers.  For this example, we will assume the roof mount.

The remaining electrical hardware will be around $500 plus the cost of your electrician.  The more DIY labor you supply, such as mounting your racks, the better your cost savings.  For our example, I will budget $500 for our electrician.

So, adding $500 for shipping and miscellaneous,  you have built your DIY EV fueling station for  $5040 before tax credits.  You have a 30 percent tax credit from the federal government through 2015. Most states range from 10-40 percent additional tax credit. So wrap your head around this statement:   You have paid forward the cost of driving your new EV, and your next EV, and probably your next EV for between $3000-4000.

The New Nuclear Family

The New Nuclear Family

What are the weaknesses of the system? The four areas of concern are hail, wind, lightning, and theft.  All reputable panels come with a 25-year warranty on golf ball sized hail and 100 mph wind. Beyond the manufacture’s warranty, all reputable home owner policies cover all four.  If your provider does not, there are many reputable providers more than willing to write your policy at no additional cost.

Two other considerations are panel efficiency loss and geographic solar insulation.  The photovoltaic panels lose up to 20% efficiency over the 25 years of their warranty.  A 2kWh system will start out producing slightly more than the 15,000-mile driver uses.  Depending on your usage, you may add another panel and inverter over the life of the system.  This example is also geared toward all areas other than Alaska and portions of the North East and Pacific North West.

In most areas, this system will pay for itself within 8-10 years. It is difficult to know all future obstacles. Some will be good and others bad.  There certainly might come a time when your utility company no longer pays for the surplus electricity you generate and feed back to the grid. You may find in 8-10 years a need for an expensive battery backup—you know, like the old battery in your EV that is now down to 80 percent.  In time, it will make the perfect battery backup for your charging station! The glass is definitely half full.

And a closing thought  about energy independence.  You have fixed a large portion of the cost of your auto fuel for 25 years and I have to tell you, that is a great feeling every day.

Got a tip for us? Email: