Thomas W. Lewis

August 4, 2009

Nissan just announced their first mass market EV, called the Leaf.  It is a 4-door and is said to take you 100 miles between complete charges.   Probably you will need to to buy or lease the battery separately, but Nissan appears to be focused on keeping the total cost more reasonable than the other announced EVs of similar quality level, such as the Mitsubishi i MiEV.  Some of the reports indicate that the car itself may only be available via a lease.  It is planned for introduction to selected areas of the US market late 2010.

Overall, it looks a bit better than the Versa upon which it is based.

Also, Nissan is planning some nice features like a web-based control of car functions, and text alerts for state of charge.  The navigation system will show graphically how far you can reach on your charge, and where the charging stations are.

Power is 107 HP, torque is 208 ft-lbs, and top speed is 87  MPH.  Battery capacity is 24 kWh.

According to Autobloggreen, “More impressive is the battery pack’s 50 kW DC fast-charge capability, which is capable of accepting an 80% charge in less than 30 minutes, or an extra 50 km (31 miles) worth of range in about 10 minutes.”  These fast chargers will be special 3-phase units that will not be priced for individual car owners.  Using 200V in-home charging will require about 8 hours, and since we use 240V here in the USA for electric dryers, the rate will be 8 hours or less.

Here are some links:

Nissan

Autobloggreen

Reuters

WSJ

YouTube

USA TODAY

I just noticed a write-up on the Remote HVAC Control and Home Power Monitor on ioBridge: link.  Oh, the power of recursion; again.

California bill AB811 was passed a year ago.  It allows cities and counties to make low interest loans to homeowners for the purpose of installing permanently attached energy efficiency and solar electric systems.

What makes the idea different is that homeowners would pay the loans back though assessments on property tax bills.  The liens transfer to any subsequent owner if the property is transferred. 

It should be easier for cities to raise bond money to finance these programs because the loans are secured by liens.  With property values lower, and more people out of work, perhaps many homeowners will get a better rate for funds if they get it through this new type of program compared to a traditional second mortgage.

Now cities need to step up to the plate and implement the program for their residents.

A company called Renewable Funding is promoting this financing arrangement.  Check their link below to learn more.

CityFIRST Overview

This new partnership could be huge for SunPower to provide financing for commercial and utility scale systems.  Also, it signals an opening up of credit for renewable energy in general, which is critical because banks stopped buying tax credits last year when the economy turned.  These tax credits are integral to power purchase agreements (PPAs) which is an important arrangement for the larger projects.

Business Journal Article on Partnership

Wikipedia Entry on PPAs

July 20, 2009

This is a typical 4-wire system (1 heat & 1 cool) operating at 24VAC.  The furnace has a transformer that supplies the 24V which is wired to the RH (heat) and RC (cool) terminals on the above block.  The thermostat decides when to activate the fan, AC compressor, or furnace gas valve by sending the 24V to the G, W, or Y terminals respectively.

I decided to use the Normally Open connection on the relay board.  So, in the case power is lost to the relay, it will revert to an open connection, and the thermostat will be disabled.  I thought this was important because if we are traveling, I want the HVAC system to turn off when something goes wrong.  Of course this means the system will turn off if we are home when something goes wrong as well.

Now, when we all go on vacation, all we need to do is decide if we might need heating or cooling when we return, and we will set the thermostat in that mode before leaving.  If we had a newer auto changeover thermostat, all we would need to do is turn it on auto.  Then we disable the thermostat using the ioBridge control, and leave.  When we are returning, we just enable the thermostat via ioBridge (like via an iPhone on the way home from the airport.)  The house will be comfortable when we get home.

Likewise, if we are out for the day and decide to not come home that night, we simply disable the thermostat via ioBridge until just before we return. 

July 10, 2009

I completed the installation of a power monitor for my home.  The web page is here.  The chart comes from Google Charts; you need to wait for the chart to build over time. 

It is intended primarily for relative power monitoring, not ultimate accuracy, and the energy can only be logged for short periods.   It does not include power to my air conditioner (which we do not use much anyway) because that load is connected directly to the main panel, which is not adjacent to the Ethernet port I have in my garage. 

There are also two temperatures reported on the web page, as described.

Credit given to Jason Winter who created this solution and published it here and here.

My implementation is slightly different from Jason’s.  I utilized a different op amp (AD627), a different offset (0.5 VDC), and keept mine on a breadboard for future upgradability.  I used a box with an added terminal block to convert from the CT banana plugs to lead wire for connecting to the conditioning circuit.  Of course I lifted his HTML code, but modified it for my ioBridge widgets, as well as for my power factor assumption and calibration constants.

A key learning is how difficult it was to install the current transformers.  There was barley enough room for them in the sub-panel.  I used the Steren PUN-285 as suggested by Jason.  But these CTs are really for temporary installation, and therefore are not optimized for minimal space.  It was a chore to get the panel cover back on in my particular case.

Sub-panel with power monitor above

Detail of current transformers on two legs.

Detail of ioBridge (left), breadboard with two conditioning circuits, and terminal conversion box.

June 21, 2009

Google wants to do smart charging to smarten up the grid.

Link1
Link2

June 13, 2009

Tim Nolan has had a site up for years that included a home build Maximum Peak Power Tracker (MPPT.) Recently, he redesigned the project and this time used an Arduino hobbyist microcontroller board to accomplish the same function with less complexity and lower cost.

Link

Any solar inverter worth its salt has this function build in. The MPPT is essential for maximizing the conversion efficiency. It is great that Tim has now published a way for those familiar with Arduino to make their own MPPT.

June 6, 2009

Here are some interesting articles about Cisco and the SmartGrid.

Story 1

Story 2