Costs and Benefits of a Solar-Assisted Hot Water System Carl D Costs and Benefits of a Solar-Assisted Hot Water System Carl D. Martland Sugar Hill, NH

Ideal Location: Southern exposure Roof with 45-degree angle

Glycol is pumped up from the basement, circulates through the panels, and returns to the basement. Glycol warms up as it circulates through tubes enclosed within each of two insulated panels.

Hot water comes out of the top of the tank. Electric coil in top of tank (back up to solar system). Warm fluid enters the bottom of an 80-gallon hot water, circulates through a maze of pipes, and is pumped back to the roof. Thermostat Overflow pipe Pump Expansion Tank

Hot water comes from the top of the tank Cold water can be mixed with hot water to send water to house at desired temperature (e.g. 120 degrees) Temperature of hot water coming from the tank

Temperature at the Collector and in the Tank: the Pump Runs if it is at Least 10 degrees warmer at the roof

Timing for Using Electricity Event 2: off at 10:07 am Event 3: on at 1:00 pm

Cost of System: $11,829 $11,829 Materials $7,463 Solar Panels (two) $3,202 80-gallon solar/electric tank $2,177 Pump, pipes, tubing, valves, glycol, insulation, controllers, etc. $2,084 Installation of solar system $3,350 Preparation of roof for installation $950 Professional installation of panels $2,400 Electrician $385 Plumber $631 Total $11,829

Net Cost After Rebates: $6,780 Cost of System $11,829 Credits $5,049 State renewable energy rebate $1,500 Federal tax credit (30%) $3,549 Net Cost $6,780

Typical Tempteratures of Glycol and Hot Water in 2012/2013 (clear days or days with some sun or light clouds)

Tank Temperature on Clear Days (hours of sunlight more important than temperature)

Tank Temperature on Cloudy Days

Energy Savings: $620/year Oil Saved (gallons/year) 190 Price/gallon $3.89 Savings per year $740 Added electricity (kwh/year) 800 Price/kwh $0.15 Added cost per year $120 Net Annual Savings $620

Return on Investment (ROI): 9.1% in the First Two Years Cost of Installed System $6,780 Annual Maintenance $0 Annual Net Energy Savings $620 Estimated Net Benefit ROI 9.1%

Estimated ROI Over Life of System: Cash Purchase Cost of Installed System $6,780 Annual Maintenance (equivalent annual cost) $50 Annual Net Energy Savings $620 Estimated Net Benefit $570 ROI 8.4%

Estimated ROI Over Life of System: Borrowing 70% of Initial Expense Cost Benefit Net Cost of Installed System $6,780 Home equity loan (20 years, 4%) $4,780 Net Investment $2,000 Reserved for maintenance ($50) Annual Loan Payment ($350) Annual Net Energy Savings $620 Annual Net Savings $220 ROI 11%

Conclusions The system works as expected: Installation completed on time and on budget No operating problems System supplies nearly all hot water from May through September and during good weather the rest of the year It was a good investment for us: State rebate and federal tax credit reduced initial expense by more than 40% ROI greater than 8%

Costs and Benefits of a Solar-Assisted Hot Water System Carl D. Martland November 12, 2014