Solar Spectrum

Solar Spectrum

A large collection of solar-thermal system designs for about every need and size of structure. All free.
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Filling the pressure: Sizing an expansion tank correctly

You’ll need a few basic details about your system. Here are some good questions about the correct sizing for an expansion tank from a conscientious installer — which I know includes all of us. Q

Incoming water temp can determine size of collectors, storage

As you get ready to design a solar thermal system for your home, there’s one factor you may not be considering that could make a bucket load of difference: What’s the beginning temperature of the wate...

Now for a slightly larger project: Designing a medium-sized commercial solar thermal system

A recent blog post discussed light commercial systems for restaurants and other similar businesses. But what if you need a solar thermal system with a bit more uumph? Here’s the recipe for a solar hot...

This design for a light commercial thermal system is effective, simplified

I’m asked, more and more, to provide a solar hot water system design for light commercial systems. There is, indeed, an effective and simple design template for smaller commercial systems th...

Drainback vs. pressure: A question for the ages

Pressure or drainback? That’s probably the question I get asked more than any other: Should I choose the more popular pressure-glycol system, or go with a drainback system? Here’s the answer: It...

Sizing home system based on temp of incoming water, with helpful chart

Earlier, I published a chart that helps size a solar hot water system for your home, but after hearing from some people I realized I needed to make it more simple. So, to back up and provide a bit ...

Commercial solar: With tankless water heater, you don’t pay to heat it ’til you need it

Here’s a new concept for commercial solar: a 250,000-Btu tankless water heater. It comes down to this simple philosophy: Don’t pay to heat ’til you need it. As you study this concept illustration, you...

Drainback with tankless is less costly, more efficient

Today, as part of our ongoing series of basic solar designs, we look at a drainback system using an efficient solar storage tank and a tankless water heater as backup. This design is fairly uncompl...

Condensing boilers and baseboards: A great matchup

Do you need a more efficient (and expensive) modulating condensing boiler if you have baseboards? That was the question posed in a discussion group I follow, and many contractors said, “No, a cheap...

Flat plate vs. evacuated tube: Which is the winner?

By Tom Scheel Red vs. Blue. Tastes Great vs. Less Filling. Kirk vs. Picard. Epic battles for which there really are no right answers. Enter into that pantheon the great debate between flat plate vs.

Drainback solar system at airport gains every drop of energy from sun

Out with the old (over complicated, expensive solar). In with the new (better and more efficient solar at lower cost). Case in point: the Minneapolis- St. Paul international Airport’s cutting-edge ...