In previous blogs we talked about “Green Energy” and how seeing ourselves as energy producers is the first step in setting ourselves free from fossil and nuclear fuels.  We looked at Solar Hot Water being the easiest and most cost-effective way to be an energy producer, and that is safe, durable, reliable, renewable and cost-effective.  We also looked at what hot water can do – heat space, melt snow, heat pools and spas, and save high volume business or institutional users significant amounts of money each year to pre-heat unlimited amounts of clean water up to 180 degrees Fahrenheit.

We have explored the components of a solar hot water system – the collectors, heat exchangers, storage tanks and fluid mediums .  And we have looked at the two most common system types : Closed-Loop and Drainback and how they work.

Now lets step back and look at the world of renewable energy systems and where Solar hot water fits in.

The common perception of Solar hot water is that the systems don’t work.  This is a continuing hangover from the period from 1973 to 1986, when the industry enjoyed a double-edged renaissance.  The first oil crisis initiated strong interest in renewable energy systems and a lack of industry standards allowed an army of small manufacturers to loose a host of low quality systems on an unsuspecting market.  Hence, those ugly panels on grandma’s house that never worked.

The party came abruptly to an end in 1986 when the 40% investment tax credits ended.  A full 97%, effectively the entire industry, went out of business. Many deserved that fate.

With a resurgent interest in renewable energy in the last few years, photovoltaic (PV) panels have garnered the most attention and interest.  Solar hot water manufacturers, now bound by strict standards of quality control set by the Solar Rating Certifications Corporation (see http://www.solar-rating.org) have labored quietly creating a new generation of Solar hot water components and controls.  As PV leaders struggle to reach from 15% to 20% efficiency in their collectors, Solar hot water manufacturers are routinely producing 75% to 80% and they do it with products that cost a fraction of their electrical cousins.

So why isn’t Solar hot water wildly popular among the gurus of renewable energy?  Follow the money,  billions of dollars are invested by public and private sources in a frantic search for viable replacements for fossil and nuclear power generation.

Solar hot water doesn’t need billions of dollars to chase a mythical capability.  It works quite well right now, thank you.  With current levels of government support and mandated utility rebates available just about everywhere, it should be booming, and when real estate awakens from it’s long slumber it will.

Most people want to know what the “Return on Investment” is on a Solar Hot water system.  Its not hard to figure, and improves with the number of people served on an individual system.  It gets even better when energy costs rise, which seems likely.

The real question is whether we see ourselves as energy consumers or producers as we discussed way back in Solar Hot Water 101.  Once we cross that line then the decision is easy.

In previous blogs we talked about “Green Energy” and how seeing ourselves as Energy Producers is the first step in setting ourselves free from fossil and nuclear fuels.  We looked at Solar Hot Water being the easiest and most cost-effective way to be an energy producer, and that it is safe, durable, reliable, renewable and cost-effective.  We also looked at what hot water can do – heat space, melt snow, heat pools and spas, and save high volume business or institutional users significant amounts of money each year to pre-heat unlimited amounts of clean water up to 180 degrees Fahrenheit.

In the last blog we looked at different types of collectors, heat exchangers, storage tanks and circulation pumps that make a system work.  Now we’ll take a look at the 2 main types of system configurations from which you are likely to choose:  ”Closed Loop” and “Drainback”.

-  First we’ll look at Closed Loop Systems:

This type uses a fluid that is charged in a closed line that circulates continuously through the collectors and a heat exchanger at or in the storage tank.  The fluid is always in the collectors so it must be both freeze and boil protected.  This is normally accomplished with a mix of distilled water and propylene glycol.  In a 50/50 proportion, the resulting fluid has a freezing point of about 40 degrees F below zero, and a boiling point of about 240 degrees F.  While this is good protection from damage due to cold weather or overheating, the lower viscosity of the fluid, and it’s ability to transfer heat, reduces the efficiency of the system.

The closed loop must also include an expansion tank to allow for expansion and contraction as the fluid medium heats and cools.

A great potential feature of a closed loop system is the easy pairing of it with photovoltaic powered DC pumps that intuitively work when the sun is up and stop when the sun goes down.  The closed loop has no head pressure so only a small pump is needed to overcome the line friction of the loop.  This is truly the most “solar” of solar systems and is ideal for off-grid applications as there is no need to plug anything into a wall outlet (i.e. Controller, pump, etc…).

-  Drainback System:

The drainback system can use water as the fluid medium and still remains freeze protected.  Sensors in the storage tank and collectors activate the system when heat is available and needed, and shut the system off when the tank is hot or the sun goes down. When it’s shut down, the system is configured to drain the collectors and lines into a small storage tank that is protected from freezing in a conditioned space. Water is about 20% more efficient as a heat transfer medium compared to propylene glycol, which makes this system an attractive choice.  Drainback systems still use a heat exchanger and require a larger circulation pump than on a Closed Loop system. This system has the advantage of high efficiency and only works when needed, reducing the actual operating periods to the minimum required.

Now we’ve covered the basics of solar hot water, and you should have a good understanding of the technology.  Solar hot water has a long and rich history, and a bright future in the coming world of net-zero energy producing buildings of all types and uses.

In the next issue: Solar Hot Water 501 – Economics

In previous blogs we talked about “Green Energy” and how seeing ourselves as energy producers is the first step in setting ourselves free from fossil and nuclear fuels.  We looked at Solar Hot Water being the easiest and most cost-effective way to be an energy producer, and that it is safe, durable, reliable, renewable and cost-effective.  We also looked at what hot water can do – heat space, pools and spas, melt snow and save high volume business or institutional users significant amounts of money a year to pre-heat clean water up to 180 degrees Fahrenheit.

Our next step is to take a look at how Solar Hot Water works. There are many ways to collect and store heat from the sun, and they all start with a collector.

The first collectors were just water vessels with a dark surface left in the sun to warm.  These date back at least 6,000 years, and continued right into the late 19th century when the first commercial collectors appeared on the American market. Thousands of these were sold by the year 1900.  The first collectors were what we now call “batch” collectors – a simple glass covered box with a small tank of water inside. It worked pretty good during the day but cooled quickly at night.

Next came the glazed flat plate collector, which is still in wide use today.  This is an insulated glass covered box with small tubes that circulate a fluid from bottom to top.  Metal plates bonded to the tubes, collect and conduct heat to the fluid within which moves on to an insulated tank for storage.

 (not a Sunvelope collector)

A simple uninsulated flat plastic collector is very popular for swimming pools, is relatively inexpensive and very effective.

Other types, such as “Evacuated Tubes” or “Concentrated Troughs” are more specialized, produce dangerously high temperatures and have more limited applications for small installations.

Heat exchangers are simple devices that transfer heat from one fluid to another, and are sometimes built with 2 layers to protect against accidental contamination between the fluids.  Some heat exchangers are stand-alone devices that can carry heat to a specific task – say a spa, baseboard heater or air duct.  Others are integrated into storage tanks that range from 60 gallons up to 2,000 gallons or more.

The storage tank is the key to a successful system.  It must be well insulated and big enough to hold heat for hours, days and sometimes for weeks.  Think of it as a big solar battery.  Bigger is better – especially if you have a lot of expectations for your system.

Now you will need circulation pumps to keep fluid moving to and from your collectors, through your heat exchangers, and back again until you have enough heat or the sun goes down.

With collectors, a storage tank, a heat exchanger and a circulation pump you can collect heat and deliver it to your clean water.  And you can do that everyday!

basic solar water heating diagram

In the next issue – Solar Hot Water 401 – “Closed Loop or Drainback?”

By: Peter J. Mokler

Architect, LEED A.P.

In the last issue we talked about “Green Energy” and how seeing ourselves as energy producers is the first step in setting ourselves free from fossil and nuclear fuels.  We looked at Solar Hot Water being the easiest and most cost-effective way to be an energy producer, and that is safe, durable, reliable, renewable and cost-effective.

Great.  We can make clean renewable hot water.  But what can it do?

Let’s start at home.

Hot water can heat a hydronic floor or baseboard radiators, heat air in a hydronic ventilator and feels great in your pool, spa, bathtub or shower. Hot water can wash your clothes, dishes, home and car, and melt the snow and ice in your driveway, walks, decks and even your roof. And it can keep a greenhouse warm to protect your plants from winter frost.

These things are a major portion of your home energy needs.

Nice.  And at work?

Hot water can save substantial amounts of money for high volume commercial and institutional users such as municipal pools, hospitals, restaurants, resorts, hotels, nursing homes, laundries, factories – any use that needs moderate heat up to about 180 degrees Fahrenheit.

And all this happens with existing systems and technology.

In both residential and commercial uses there are two basic approaches to installing solar hot water systems – retrofit or new.

A retrofitted system is installed on an existing building, and can cut down energy bills substantially.  Even small domestic systems can have a big effect, sometimes paying off in as little as three years.  Some of the challenges of the retrofit are found in integrating the solar system with existing structures and systems that never anticipated them.  Although sometimes it just doesn’t work or pencil, it is always a good idea to take a look.

Are you a consumer or a producer?

“WOW! Were we ever excited to get our bill out of the mailbox to discover the savings that the Solar Hot Water has provided for us. We are down half of where we started. We are very conservative on our power usage and we are totally amazed that it would be possible for our bill to have gone down so much. Who ever thought that it would be this exciting to receive a power bill?A great big thank you to Sunvelope and your wonderful staff.”

And if you think they’re exaggerating, they sent us their power bill from the month before we installed the system and the month after. Take a look.

That’s the bill from March, with their old electric water heater. In mid April we replaced their old water heater with an 80 gallon solar storage tank with an electric back up (for cloudy days) and we installed two 4′x8′ Solar Panels on their roof. Look at the savings they had on their bill in June!

WOW! Their bill went from $113.07 to $55.84!

*That’s a savings of $57.23! More than HALF!

This is a family of 3, in palomino valley. They use a gas furnace to heat their house and have gas appliances, so this is a very accurate example showing how much of a difference a  Solar Water Heating system can make! This system cost them less

You might also notice that the billing cycle in March was only 29 days, and the billing cycle in June was 31 days. Two extra days and STILL less than half!

This customer paid less than **$10,000 for the whole system – installed! Not including any tax credits or incentives. They will be getting close to $2,000 back from NV Energy as part of their Solar Water Heating incentive program as well as almost $3,000 back from the U.S. Government as part of the 30% U.S. tax credit incentives.  When all is said and done, this customer will be paying less than $5,000 for their system, with a 10% annual Return On Investment!

*Monthly and annual savings cannot be guaranteed, everyone’s savings will be different. **Prices may vary. Price listed does not include any rebates or incentives.

They give plenty of room for you to express anything you want to get across to consumers or to highlight features about your products and services that might otherwise be overlooked.

I just signed up and listed Sunvelope Solar, we’ll see how well they work.

Here’s our listing: Solar Water Heating Systems

Use the link to try it out if you are interested, it’s free!

Copy and paste this if the link does not work: http://www.thumbtack.com/nv/sparks/solar-water-heater-installation/solar-water-heating-systems