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Vacuum Tube and Hybrid PVT Panels Comparison for North America

by ROGER ABDO

Introduction

Hybrid Photovoltaic and Thermal solar panels are a combination of Two Solar Technologies: Photovoltaic Technology producing electricity in  form of DC current and Voltage and the Flat Plate Glazed Panel producing thermal energy in form of Hot Fluid (either Water, Water and Antigel Mixture or any other compatible fluid).

The first Layer of Photocells absorb a portion of sun's radiation, and the hydronic copper coil behind it aborbs the remaining radiation, as well as heat loss generated by the photocells, and conveys it to the circulating fluid. 

At Standard Test Conditions (STC), Hybrid PVT panels have the highest ratio of energy output (both electrical and thermal) to energy input from the sun. In Nordic Climates, such as the majority of Canadian cities as well as cities in the northern portion of the US, STC conditions represents a small percetnage of the annual bin hours. 

This blog simulates Hybrid PVT panels in multiple cities accros North America and compare their performances to Vacuum Tube Solar Panels. For the purpose of this blog, we will be comparing PVT and Vacuum Tube solar kits having similar aperture areas.

Simulated PVT and Vacuum Tube Kits

We will be comparing 2 simple Domestic Hot Water heating Solar kits: The PVT kit has an aperture area of 5.64 m2 (3 Panels aH72SK) and the Vacuum Tube one has an aperture area of 5.666 m2 (2x30 Vacuum Tube Solar Collector). Both Kits have 2 Modules and are installed at a solar azimuth of 0 and a tilt angle of 45 degree. On the demand side, they serve a house occupied by 2 people requiring Domestic Hot Water at 120 °F (48.9 °C).

Simulation Results

Simulations were carried out using Polysun Software for these cities: NY City, Boston, Seattle, Chicago, Montreal, Halifax, St-Johns (NFL), Calgary, Edmonton, Victoria, Vancouver, Revelstoke, Winnipeg, Saskatoon, Ottawa and Toronto. Qsol represents the annual KWh of Hot Water or Hot Fluid produced by each kit and Qinv represent the annual KWh of electricity produced by the Hybrid PVT kit.

New York City (NY)

In NYC, Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Boston (MA)

In Boston, Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases (close to zero) in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Chicago (IL)

In Chicago, Vacuum Tubes have superior thermal performance than PVT (except for the month of may). Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Seattle (WA)

In Seattle, Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Montreal (QC)

In Montreal (QC), Vacuum Tubes have superior thermal performance than PVT. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Halifax (NS)

In Halifax (NS), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

St-John's (NFL)

In St-John's (Newfoundland), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Calgary (AB)

In Calgary (AB), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Edmonton (AB)

In Edmonton (AB), both technologies have the highest output in Canada and that is mainly due to the abyndance of sunny hours in the rockies.When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Victoria (BC)

In Victora (BC), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Vancouver (BC)

In Vancouver (BC), same as in Victoria (BC), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce more energy than Vacuum Tubes.

Revelstoke (BC)

In Revelstoke (BC), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels similar amount of energy than Vacuum Tubes.

Winnipeg (MB)

In Winnipeg (MB), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce similar amount of energy than Vacuum Tubes.

Saskatoon (SK)

In Saskatoon (SK), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels higher amount of energy than Vacuum Tubes.

Ottawa (ON)

In Ottawa (ON), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels produce higher amount of energy than Vacuum Tubes.

Toronto (ON)

In Toronto (ON), Vacuum Tubes have superior thermal performance than PVT all year long. Performance gap increases in winter and decreases in the summer. When adding both thermal and electricial energy, PVT panels higher amount of energy than Vacuum Tubes.

Which Technology is more suitable for my project?

Multiple Factors influence the decision to wether to go for Vacuun Tube, Hybrid PVT or simply Photovoltaic. Energy prices, availability (current and future), as well as application and geographic location can make one choice of technology good for one project and not good or avereage for another one.

Assuming a homeowner in Toronto (ON), where the KWh of Natural Gas is around 4 cents and the KWh of electricity (ON Peak) is 18 cents. The Vacuum Tube Kit will generate an annual THERMAL ENERGY saving of 4098 KWh/year x 0.04$/KWh = 163.92$/year. The Hybrid PVT Kit will generate an annual THERMAL ENERGY saving of (3350 KWh/year x 0.04$/KWh) + 1157.4 KWh/year x 0.18$/KWh) = 134$ + 208.33$ = 342.33 $/year. The elctrical Energy produced by the PVT Panels represents 28% of the energy produced by Vacuum Tubes, however its $$$ value is 200% of the energy produced by Vacuum Tubes.

if the same house was located at the outskirts of Toronto, where people don't have access to Natural Gas. Instead they heat their DHW with propane boiler and they buy propane at 14 cents / KWh. The Vacuum Tube Kit will generate an annual saving amount of 4098 KWh/year x 0.14$/KWh = 573.92$/year. The Hybrid PVT Kit will generate an annual saving amount of (3350 KWh/year x 0.14$/KWh) + 1157.4 KWh/year x 0.18$/KWh) = 469$ + 208.33$ = 677.33$/year. The elctrical Energy produced by the PVT Panels represents 28% of the energy produced by Vacuum Tubes, however its $$$ value is only 36.3% of the energy produced by Vacuum Tubes.

The above numbers will be different if the same project was executed in Saskatoon, Chicago or Edmonton. Labour prices (Unionized or Not), availability of government grants, and other local factors play a major role in the feasibility and do-ability of such a project.

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