Guest Post from Wayne Mackey: How I Reduced Home Energy Consumption by 80%

On December 23, 2009 my wife Diane and I installed a 5.4Kwh PV Array on the roof of our home at 920 Cypress Street, Chambersburg, PA.

Prior to our “going solar” we had reduced our home’s energy use by 65% over the previous 3 years beginning in 2007 through energy conservation, energy efficiency and renewable energy. Had we not made these reductions in energy usage before hand, this same 5.4Kwh PV Array would have only been able to supply our home with just 27% of its energy needs. Therefore, the actual pay off on our investments would have taken perhaps as much as 20 years rather than what we now estimate to be at just over 4-5 years.

Our PV Array and green energy retrofits will provide us decades of free energy and both save and make us money at the same time. We estimate that after the payback time of 4 -5 years (around 2014), that over the following decade (2024AD) we will have saved at a minimum of $25,000 by not having to pay 67% for electricity from our utility to power our total electric home, and we could probable receive $23, 450, or more, for our Renewable Energy Credits over that same period of time, for a positive net gain of at least $48,450.

Of course, we are assuming that electric utility rates will stay the same between now and then. But let’s try to be realistic. Is there anyone that thinks that will happen? If the past five years are any gage, wherein between 2005 and 2010 they have gone up 58% from 7 cents per kilowatt to 12 cents per kilowatt, we feel that it is an unrealistic expectation.

December23, 2009 and January 31, 2010 our 5.4Kwh PV Array produced 22.3% of the electricity we needed to power our home. Our house used 1448Kwh of electricity and our PV produced. Our daily outside temperatures ran between 9 – 30 degrees F. Estimated savings $90.00 on electric utility bill for December 2010 based on previous 5 year monthly average. House average used 47.05Kwh electricity every day.

February

December is quite possibly the very worst time to install a solar PV Array here in the North Easter US. That is because you will probably spend the next 12 months making up the power you are not able to produce from your PV Array that you needed to power your home during January thru March. During the first 3 full months and one week (or 13 weeks, until March 31,) our house used a total of just 3 weeks during February of 2006 when we were using 121Kwh per day on average.

Between The 5.4Kwh PV array produced 2010 we had the highest record snowfall on record for our area in many years. By February 6, 2010 we had 22 inches of snow on our roof and solar panels. On February 10^th, we decided to remove the snow. On February 14^th, we saw a record high 5000 watts being produced by the PV Array but it was short lived because of the low angle of the sun and the short 7 hours of sunlight. We saved $96.93 on Electric based on previous 5 year monthly averages of $208.00 per month. 214.5Kwhs for the month of February 2010.House average used 40.75Kwh every day.

March

To date, using renewable energy, we have saved 7,453 pounds of Co2 from going into the atmosphere.

March 8, 2010 was to the best of my knowledge the very first time in the history of the Borough of Chambersburg, Pa that a private residence generated enough power from sunlight to power their home for a full and complete 24 hours. Because of all of the energy efficiency’s like triple pane windows, wall insulation, and others, we were on many occasions able to turn off our heating system even though the outside temperatures were between 24 and 60 Degrees Fahrenheit. On March 21, 2010 we reached our first Renewable Energy Credit, now worth $375 by generating 1000 Kilowatt hours of electricity and reporting it to our REC aggregator via e-mail. We saved $269.78 on Electric. House average used 10.03Kwh every day.589.3Kwh of electricity. That was 77.1% of our total electricity needed to power our home. By March 31, 2010 our house had used a total of 3335 kilowatts from the Borough of Chambersburg starting on December 23, 2009 thru the end of March 31^st. Solar power provided 1,272Kwh additional power. That was a full 13 weeks. Compared to February 2006 when our home had consumed 3, 676 kilowatts in just four weeks before we began our energy conservation, energy efficiency and renewable energy measures.

November 2010. On November 6, 2010 we received our Utility Bill from the Borough of Chambersburg for October production and usage. Out house used 487Kwh and we produced an extra 125Kwh above that figure. According to the Borough utility bill, we used and created a total of 612Kwh for the month of October. The Borough gave us a credit of $6.34 off our other utilities and our total monthly utility bill was just $27.79. Starting on November 1^st, 2010 we started to run our air source heat pump continually 24 hrs a day. On November 12, 2010 we received our 5^th (REC) Renewable Energy Check for $344.10. The PV Array produced a total of 400Kwh for the month of November 2010. 

On December 8, 2010 we received our Electric Utility Bill for November 2010. They gave us credit for producing 466Kwh of electricity from our PV array and we used 310Kwh of borough electricity. Our electric bill for November 2010 was $38.60. The first three weeks of December 2010 were mostly cloudy with temperatures running consistently 10 degrees below normal. The entire month of December was exceptionally windy.

First year Conclusions:

December 2010 average daily temperatures averaged 5 Degrees above normal for the entire month. There were a total of 9 days out of the month with an average daily wind speed above 15 mph.

We consumed a total of 9,618Kwh of electricity for the year. Of that, 6,730Kwh was produced from solar power and 2,888Kwh was purchased from the electric utility. To put it another way, solar power provided 2/3 of the energy it took to power our home during the first full year of operation. We used an average of 9.57Kwh per day of electricity from the Borough of Chambersburg and produced an average 18.8Kwh of solar power a day over the preceding 365 days from solar power at the same time preventing 11,441lbs of CO2 from going into the earth’s atmosphere.

We saved a total of $2,400 on electric our utility bills and made $1,810.15 from the 5 Renewable Energy Credits bringing the total payback on our investments in solar energy to $4,210.15 for the year. Our out of pocket expenses for both the Solar PV Array and the Solar Domestic Hot Water systems together cost a total of $21,300 after rebates and grants from the state and federal government. Had we continued to consume electricity from the Borough of Chambersburg this year, at the same rate we did back in 2005, our electric utility bill would have been $2,902.88. Our anticipated payback is now projected to be 5 years. After that, it is all profit for the next several decades. The Borough of Chambersburg paid us 6 cents per Kwh we generated from our PV over and above what we used.

2010 was surprisingly cloudy with 13 days out of 31 days either cloudy to very cloudy. However, very little rain was produced during this period. As a result our PV Array produced 681.25Kwh for the month. But because of those same clouds, outside temperatures were moderated during the first three weeks, and therefore, our PV still produced more electricity than what our house consumed. September 9, 2010 we received the Borough of Chambersburg utility bill and they gave us credit for the 130Kwh that our PV Array Produced over and above what our house used in August and deducted $7.89 off our other three utilities of water, sewer, and refuse. The PV Array produced an average daily (plus) 4.19Kwh extra each day over and above what was needed to run the house. The first three weeks of September 2010 were for the most part sunny but came with mild temperatures. We had another 3 day heat spell late in the month bringing the total number of 90+ degree days to a total of 47 for the year to date. Our 5.4Kwh PV array produced a total of 652.68Kwh for the month of September 2010.October 2, 2010 the AM outside temperature was 44F. Inside our house it was 74F, demonstrating how effective very good insulation materials can be at reducing the need for any internal heat source. After three and a half days of very cloudy weather and rain during the 4^th thru the 7^th of the month, the inside temperature of the house remained at 68F. The sun will come out tomorrow. Because of the cloudy weather the past three days, the temperature in our solar hot water tank dropped to as low as 74F, but that is still higher than the incoming city water temperature. This meant that our electric hot water heater set at 110F had to turn on for the first time since May to raise the water temperature to the desired temperature. The result caused our overnight electrical energy consumption to go up from an average of between 5Kwh to 6Kwh to 9Kwh on two separate occasions. Thus proving that our Solar Domestic Hot Water system does, in fact, save us between 3Kwh and 4Kwh at night when it is being charged by the sun during the day, which is at least 80% of the time so far. Since our Borough of Chambersburg water temperature is usually around 55F when it comes into our electric water heater and the highly insulated solar hot water tank only dropped to a low of 74F it is still more energy efficient than what would otherwise be. Borough Electric Bill Came on October 8, 2010 and it showed that our 5.4Kwh PV Array produced a total of 692Kwh in September and we had generated an excess of 265Kwh for which we received $16.51 off our total utility bill for September. The net total utility bill was $28.48. On October 24, 2010, not only had our PV Array produced all of our energy for the past seven months, but we were also able to produce 1,000 extra Kwh hours off our March 31^st total of 3,335Kwh bringing it all the way back to what we had used between December 23, 2009 to February 11, 2010, or 2, 335Kwh. We only ran our electric heat pump a total of 4 hours this month to maintain an indoor temperature of 68F. Our PV system produced a total of 555.34Kwh for October 2010. We only ran our heat pump just 4 hours all month to maintain an indoor temperature of 68F.