Wednesday, January 19, 2011

Cre8-ing Electricity: Results from 1.5 years of Solar

So far, I've shared how we decided to invest in a Photovoltaic Solar System and how the installation went.  Many people ask me how the system is performing and how it affects us on a day-to-day basis.  Let me start with the easy stuff...

How Does Solar Affect Us on a Day-to-Day Basis?
Not at all.  In fact, we could just forget about this until our electric bill comes and it is lower than expected (if I didn't obsessively check the performance on a daily basis).  In our installation, the solar panels are only visible from the back yard, so we don't even look a them.  There is no change to the way the electric system works within our house.

How Did We Prepare (Reducing Electricity Usage)?
Before we went ahead and invested in this system, we took many steps to reduce the electric usage in our home.  Some of the biggest impact items were: using a programmable thermostat to lower the usage of AC/Heat Pump, add weather stripping, and lower the temperature on our hot water heater.  Some other items are:
  • put vampire energy hogs (such s the cable box) on a timer, 
  • not using dry cycle on dishwasher, 
  • switch to CF/LED lighting
  • and washing clothes in cool water.

How Much Do We Produce?
Yeah, this is where I get to show my graph.  I am a geek for Excel!  There is a lot of information in this graph.  The bars represent our total electric usage each month.  The "green" section of the bar shows the amount each month that our solar generates.  The "red" section of the bar shows the amount of electricity that we use from BGE.  The line on the graph shows the percentage of our total usage that comes from solar each month.

What Affects Production the Most?
The biggest barrier to production is 2 feet of snow covering the panels!  In fact, the only times we have had zero production is when the panels are covered with snow.  The other factors that affect this are the season (number of hours of daylight), how cloudy the sky is, and the temperature (solar panels are more efficient in cool weather rather than in very hot weather). 
What Percent of Our Electric Usage Comes From Solar?
Here's another (far more simplistic) graph.  BGE is our electric company.  We have no gas in our area, so all of our heating and cooking needs are met by electric.  To date, about 46% of our electric usage comes form our solar system.  When we first looked into this, I was very set on having a system that provided 100% of our needs.  After evaluating the investment, it was just not feasible for us.  Also, there was not enough room on our roof to support this.  If you look at the first graph, you can see how this percentage varies over time.  In the spring and early summer, almost all of our energy can be supplied by solar.  In the winter, it is a very small percentage.  This is not just because we generate less electricity in the winter, but because we tend to use the heat in the winter a lot more than we use the AC in the summer.

What Kinds of Issues Have We Had?
I hate to say this, because I don't want to jinx it, but we have not had any issues so far.  I am hoping that keeps up because maintenance expenses would really delay our return on investment (ROI) timeline.

What is the Return on Investment (ROI)?
Based on the tax incentives we have seen so far and based on what we can expect to save in electiricity costs in the future, our system should pay itself off by 2015.  We should break even within 5.5 years.  After that point, all that annual savings  is just money in our pocket (or in 529 plans as the case may be).  I was willing to pursue this with a 10 year ROI, so I am very pleased that it looks like it will come in under 6 years.

How Has This Changed Our Electric Usage?
I was really hoping that once we had the system installed we would continue to cut our electric usage (motivated by the desire to see that meter run backwards).  Unfortunately, this has not been the case.  Our usage has  been creeping upwards.  With only 1.5 years of data to look at, it is hard to say if this is because of the extreme weather we have been having (extremely hot and extremely cold) or just because we have become lethargic about reducing our usage.  Time and data will tell!

1 comment:

smurp said...

So this was a while is it now? Still working out like you hoped?