Today’s solar thermal options are cheaper, more efficient to drive

The Ford Mustangs that came out in 1964 were awesome – but they got 14 mpg. Today, you can buy a Mustang that gets 30 mps, plus has four times the horsepower.

Nostalgia is just fine. However, when it comes to solar, old designs are anything but collectible. The efficiency and cost of solar thermal systems have evolved in a way that matches automobiles. The trouble is many of us are driving those 1965 Mustangs as our primary car.

Less efficient 1980s designYESTERDAY’S SYSTEMS: In the 1980s, your basic solar hot water system included boilers, separate tanks and diverter valves, blending solar-heated water into the space heating and trying to match the boiler’s reset curve and the boiler backup to the domestic hot water. I have done dozens and dozens of system just like this over the years and they work fair. The “1980s design” illustration is actually a Viessmann design right out of its manual. Hydronics expert John Siegenthaler offers similar complicated designs with some differences. You can find those designs published in the Caleffi Idronics issue #6:

Not only are these systems labor-intensive to build, the control is crazy. Too many controls are working independently, and it takes time for trial and error to reach the correct adjustments. This is the design that inspired the title of my engineers’ solar-thermal training class, “It’s Not the ‘80s Anymore”.  It was difficult getting a happy customer. He paid a lot and the system delivered a little.

TODAY’S COMPLETE SINGLE APPLIANCE PACKAGE: These days, it’s possible to have the customer pay less and get more solar contribution through an efficient hybrid heating appliance.

Modern, cutting-edge technology has advanced to the HTP Solar Versa-Hydro. It’s essentially a highly efficient modulating condensing boiler built into its own stainless steel buffer tank. You just plug solar in the bottom where the cold water is isolated from the heated water by stratification. The tank contains the home’s potable water and is the storage for the isolated space heating. The heatpack on the top half has a built-in plate and frame heat exchanger with a variable-speed pump to supply space heating.

This appliance is fantastic for solar. If the solar can’t quit meet the demands, the burner will modulate to make up for what the solar is short. Now, you have solar as the primary contributor and the burner is secondary.

Versa-Hydro with built in solar control

Coming soon: Versa-Hydro with built in solar control

Coming soon: Currently, all solar and data-logging controls are external. However, the Solar Versa-Hydro with built-in solar control for energy monitoring and data logging will soon be on the market. You will be able to see the measured Btu heat the solar panels are producing, along with the Btu’s the gas is burning. No other product will show you how much energy you’re saving from the sun. It’s the only complete single appliance package that shows you how much energy your home is using and how much heat you’re producing for free. Built-in solar control with energy monitoring should be in every home.

Ready to put some panels on the roof? See the Drawing Library for lots of prebuilt system designs of all sizes, many utilizing more solar collectors and additional storage. Then ask for a parts list.

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