Solar PV Panel on the move

Rather than make the sensible choice and plug my solar differential controller and pump into the "mains" AC power, I chose to use a solar PV (photovoltaic) panel to supply this electricity.  This choice continues to cause issues.

The latest issue is that sometimes I find that the Taco zone valves fail to open and the solar hot water system overheats because the pump cannot pump the fluid past a closed valve.  The problem with the Taco zone valve is not clear.  I have tried to duplicate the problem by turning on and off a power supply connected to a spare zone valve.  The valve seems to work flawlessly.

On the actual solar hot water system, however, on a few occasions, I have seen the valve fail to open.  The problem is that the power available to open the valve is inadequate in the morning.  This causes continuous cycling and resetting of the solar controller and the valve.  When the solar fluid gets hot enough, the solar controller attempts to turn on the valve and the pump.  This causes too much load on the batteries and PV panel and the 24 VDC power drops below the cutout voltage of the controller (about 22 volts) and the controller shuts off and the valve closes.  With this load removed, the battery voltage quickly recovers to 24 VDC and the system turns on, only to repeat the same reset cycle.

The problem seems to be largely caused by my chosen location for the solar PV panel which is on the right of the Heliodyne solar hot water panels.  In this location, the solar PV panel is getting shade in the morning even when the hot water panels are in the sun.  The result is that there is inadequate electrical current to turn the system on when needed in the morning.  Usually this just means that the system continues to cycle and reset for 10 or 15 minutes until adequate PV power is available.  This would be no big deal.  However, the weakness in the zone valve means that under some combination of reset cycling, the valve ends up closed for the whole day.  That is bad.

To work around this problem, I have decided to relocate the PV panel to a location with less shading.  Specifically, I decided to put the panel at the top center of the hot water panels.  The picture below shows the old PV panel location.

And the next picture shows the new location.

Initially, I had rejected that location for the PV panel because I didn't want it to block the view from the window.  However, I think it looks fine at that location and the symmetry looks nice.

To hold the panel in place, I used about $100 worth of aluminum extrusions and other part from Misumi.  The aluminum extrusions are HFS8-4040 from Misumi which is 40x40 millimeters or about 1.5 inch square.  These are coupled into the Misumi frame that I used to hold up the solar hot water panels.  All the fasteners are stainless steel so the frame and fasteners should not rust.

As typical, I laid this all out in Pro/Engineer before hand to make sure everything would fit.

The first sunny day showed that this location works much better and the controller was able to turn on the valve and pump with no problem early in the morning.  Ultimately, the choice of solar PV based electricity over mains power may ultimately prove to be the right one.

Battery Pack Woes

My battery pack and I are having relationship problems.  I think it should work every day, but it thinks it deserves a day off once in a while.  So I have fired it from its job.  Let me back up for a moment.

The solar hot water system needs a small amount of electricity to run the pump, valves, and controller.  You can get this electricity from the wall outlet, but I decided to get it from a separate 40 watt photovoltaic solar panel.  But if the sun ever ducks behind a cloud, even for a moment, that power is lost, valves start closing... and repeated cloud passing can make the system cycle on and off repeatedly.  So to stabilize the system I am using a charge controller and a battery.

Charge controllers mix together electricity from the solar panel and the battery to optimize the power output.  If excess power is available, the system charges the battery.  If solar output drops, the power can be supplied from the battery, at least for a short while, and prevent valves from closing.

Charge controllers are built assuming that you are going to use either one 12 volt lead acid battery or two together (24 volts).  I have no interest in using lead acid batteries because they only last about 3 years.  So I decided to make my own 24 volt battery from AA Sanyo Eneloop NiMH batteries.

The first challenge was how many batteries did I need to mimic the 24 volts that the charge controller is expecting.  Each NiMH cell is about 1.25 volts so twenty batteries would produce a theoretical 25 volts.  This seems close enough.

Next challenge is to find a battery holder for 20 AA cells.  Since I could not find one,  I decided to put together three holders, two 8 cell (2×4) and one 4 cell (2×2).  The photo below shows what I came up with.

At the top of the battery holder is three 9V style connectors that I had to connect together to get the total 24V output.  To hold this assembly together, I bent some sheet metal and glued it to the outside.  Of course I needed to be careful that the metal did not short out any of the electrical contacts.

The Problem

Shortly after installing the system I started noticing problems with the battery.  Sometimes when I touched the battery holder, the voltage would drop to zero.  After some fiddling, the voltage would be back to normal with no clear reason way.  Other times, I would find the battery pack completely dead with the cells reading 0V each.  Upon removing the batteries from the pack they would slowly recover to about 1V suggesting they were being loaded in the pack.  I am not sure why these problems were happening, but decided a new, cleaner, battery holder might help.

I found batteries holders on the web that could hold 10 cells, so I only needed two of them rather than three holder used in the last system.  By placing them back to back, I would make one nice twenty cell holder.  I just needed to solder two terminals at the top, solder some leads, and tape the outer edges with electrical tape.

The new battery holder is installed and working well. 

I have had a discussion with my new battery pack and it has agreed to work every day and not just occasionally.  Hope springs eternal and I believe it. (for now).

Plumber makes final connection, Impressed me, not so much

Generally I am a fan of building codes that keep the public safe.  It is great that only qualified people do things like install foundations, chimneys, high voltage lines, etc.  So I was not that disappointed when I learned that I had to hire a professional plumber to make the final potable water connections for solar hot water system.

I have changed my opinion.

The idea sounds great in practice, but the execution is not always a guaranteed success.  Let me share with you my experience with the plumber.

Firstly, the task was very simple.  Break open the feed to the existing fossil fuel hot water heater, route it to the solar hot water tank, then route it back.  The idea is that the solar hot water system acts as a preheat for the existing furnace based tankless heater.

My preferred plumber (Plumber 1) wanted $1100 to do the job.  This is impressively expensive for a couple of hours of work.  I tried to hire him, but he stopped returning my phone calls due to many "no-heat" calls from a freak fall snow storm that knocked out power to many homes in the area (including mine for 28 hours).  After a while, I called on Plumber 2 that only wanted $700 to do the job, fine, I hired him.  By the time it was done, he charged me $1000 for a crappy job, but I paid him anyway.  I really should have waited from Plumber 1 due to past good experience with him.

The best thing that can be said is that the system "worked" after the plumber left and the job site was left very clean.  Unfortunately, the quality of the work could have been much better.  Let me enumerate the ways that the plumber "failed" (in my humble opinion).

FAIL 1: The Backflow Preventer
The plumbing inspector required the plumber to install a backflow preventer for some unknown reason.  Perhaps there was concern that the non-toxic propylene glycol might work itself back to the street under some impossible scenario.  Of course, that would not help us here in the house.  If the propylene glycol leaks, it will come right in to the hot water supply and we will likely drink it.  That is not much of a problem since it is non-toxic, so I don't know why a backflow preventer was needed.  Also, if this had been a fossil-fuel fired heater, no backflow preventer would have been required.  This is clearly a case of fear of the unknown, but shouldn't have been a big deal, if it was installed correctly.
  The backflow preventer should have been installed for the whole house water supply, however it was installed just in the hot water feeder line.  The resulting back-pressure made the hot water supply pressure very low while leaving the cold water supply pressure high.  The result was that it was impossible properly adjust the temperature of the shower without micron precision on the hot and cold water taps. 

So I removed the backflow preventer and installed a short length of pipe instead.

Upon removing the backflow preventer, it became clear that it was plugged with plumbing putty or some such material as can be seen in the image.  It was almost completely plugged.  What kind of plumber does such lousy work?  I thought this might have flushed out of the new hot water tank and then perhaps be the fault of the tank manufacturer.  However the backflow preventer is before the hot water tank.  So this material must have come from the plumbers new work.

FAIL 2: Can't close 1/4 valve.
If there is a 1/4 turn ball valve in the existing plumbing, you would think the plumber would know not to run pipes in such a way that the valve cannot be closed.  As can be seen in the image, the yellow handled full port ball valve cannot completely close because it now hits a pipe.  Nice work.

FAIL 3: Tempering valve defeated
If you are not a plumber, you might not have heard of a tempering valve.  This is an important piece of safety equipment in your home.  If you have a furnace (or boiler) then it is possible that it could malfunction and produce seriously hot water, e.g. 210F.  If this came up your pipes into your shower you might be badly scalded.
   To prevent this, a tempering valve is installed.  The tempering valve takes in both hot and cold water, as shown in the picture.  If the hot water is above a certain temperature, the tempering valve mixes in a small amount of cold water to reduce, or temper, the water temperature so you are not scalded.

However, my plumber managed to connect hot water to both sides of the tempering valve making is dangerously useless.  He plumbed the solar hot water into the cold port of the valve, and furnace hot water into the hot port of the valve.  The result is that the tempering valve cannot function as intended.  This is probably due to the plumber's lack of familiarity with solar hot water systems.  Alternatively, perhaps I should had developed a plumbing diagram and given it to the plumber.  That seems a little silly for someone that is supposed to know how to do this, but there you have it.

This is really a double fail because the inspector didn't catch this error either.

FAIL 4: No Unions or 1/4 turn shut off valves
This might be a bit of a nitpick, but here goes.  As recommended by the manufacturer of the hot water tank, I installed unions and 1/4 ball valves  just above the hot water tank on the solar loop.  This allows the tank to be disconnected if service is needed.

However, the plumber defeated my efforts by not installing them on the potable water side of the tank.

So if service is needed on the tank, I will need to cut the copper lines on the potable water side.

Fail 5: Pretzel Plumbing
There is a certain art to plumbing.  A well done job not only works, but it looks neat and clean.  The plumber only had to run two lines and inexplicably he didn't run them along the same path.

As can be seen in the image, the cold line (blue) and the hot line (red) are not run along the same path even though they easily could have.  This would also have avoided the cold line running into the 1/4 turn shutoff valve.


All in all, the whole job was pretty disappointing and only barely functional.  The work was neat and clean, but the plumber failed in the five ways shown above.  He also seemed quite uncertain about whether or not an expansion tank was needed and ultimately installed one even though he worked to try to convince me that a tank was not needed.  All this difficulty occurred despite A) hiring a pleasant experienced plumber and B) getting a personal recommendation to hire this plumber.

I guess tradesman, in general, are not big thinkers.  They do what their fathers and grandfathers have always done, no matter if it is good or bad, unless it totally and utterly fails to work or the law requires something new to be done.

Wish I had done the plumbing myself and ultimately will probably remove all of it and install my own plumbing correctly.

The Bill Comes Due

You know the feeling don't you?  You open up, say, the credit card bill at month's end and you think, all those little numbers cannot possibly add up to that BIG number at the bottom of the bill.  Unfortunately, all those little numbers do add up.  And so it is true with my solar hot water project.

Jumping to the bottom, the number is $12,000, give or take a little depending on what you include.  And, yes, that is a lot.  But I was not trying to do a budget job, and mistakes along the way cost mucho dinaro.  Still, assuming the federal government pays for 30% that leaves only $8400 for me to make up with oil savings and still seems possible within a few years.  More feedback on that later.

There are a handful of big ticket items and about one hundred smaller purchases.  To begin, let's talk about the larger items or main components which total $6353.12.

System Vendor Date Description Price 1 Solar Panels EcoDirect.com 08/04/11 Solar Panels $2,829.85 2 Tank Houseneeds 09/25/11 Hot water tank $1,825.08 3 Hydronics Houseneeds 08/09/11 Pump Station, fittings $557.83 4 Hydronics Portland Group 04/12/11 NA26711 Caleffi pump $363.63 5 Controller House Needs 03/29/11 iSolar Plus Controller $333.75 6 Hydronics SunVolt Energy 11/03/11 Ecocirc Pump $189.25 7 Solar PV Amazon 10/10/11 two 20 W Solar Panels $156.48 8 Hydronics Houseneeds 08/25/11 Fittings for pump station $97.25 The largest most expensive purchase, by far, is the panels at about $3000.  The good news is that EcoDirect has very reasonable shipping at $130.  The same shipping from AltE would have been over $1000.  It is also worth noting that the price would have been a lot lower if I could have used two 4×10' panels rather than three 4×6'. The second most expensive item is the solar hot water tank.  At about $1800, the price might be more than a little surprising to anyone that has purchased an electric hot water tank for, say, $400.  But there are two things to keep in mind.  First, this tank has a heat exchanger inside so I didn't need to configure an external heat exchanger and a second pump.  Second, this is a stainless steel tank that should last more than twice as long as a standard steel tank.  At least that is what I am hoping and the lifetime warranty makes me believe. Items 3,4,5, and 8 basically make up all of the Califfi Solar Pump station including the pump, controller and fittings.  This is a whopping $1,352 which seems like an awful lot for what it does.  The Caleffi equipment is nice, but it seems grossly overpriced.  Caleffi does nicely put all the little plumbing components (check valve, pump, temperature gauges, pressure gauge, air bleeder, fill ports, controller) all into one nice little package.  But the price will make the budget conscious person think about making there own system instead of buying from Caleffi. Item 6 is me having to buy the pump a second time because the Caleffi pump really isn't the right one for the job.  I have listed the old pump on ebay and Amazon and hope to recover some of the money Item 7 is the solar panels, which were also purchased twice for this job.  First I bought two 10 watt panels and then discovered that they were too small, then I bought two 20 watt panels.  Also, my insistence on using solar electric power contributed greatly to the cost of this system.  In addition to the cost of the PV panels, the pump is more expensive and the controls and electronics are more complex.   It is no wonder that AC power is used for most of these systems. All-in-All, these main components represent only 50% of the total system cost.  The "balance of system" or other parts cost just is much which is shocking.  I will cover those costs in a separate post.

Laing Eco-circ pump

   It was probably too much to expect everything to work perfectly and it hasn't.

   When the Laing Eco-circ pump turns, it is designed to use as much electric power as possible from the solar panels (PV).  Unfortunately that causes the system voltage level to drop to 17 volts and the battery charge controller stops working and eventually the controller would shut down due to lack of power.  A secondary problem is that the pump is circulating the water too fast.  It is pumping well in excess of 5 gpm (gallon per minute) which is much faster that the 2.5 gpm that is recommended by Heliodyne for the solar panels.  Too much gpm and using too much electricity.

    So I contacted Laing technical support (which appears to be Xylem Inc part of ITT) and got some great help from Amy Flores.  Long story short, it looks like Caleffi made a mistake by using the D5 "strong" pump.  That pump is really intended more for maximizing flow of fluid which is not what you want in solar hot water panels.  It is probably great for well water pumping, but not for solar hot water panels where flow control is needed.

   Fortunately Laing makes an Eco-circ D5 "Vario" pump which has, as the name suggests, variable flow settings.  There is a dial on the side of the pump where you can adjust the volumetric flow.  The image shows the two different pump types.  On the left is the "strong" pump that pumps the water as fast as possible.  The pump on the right is the "vario" version with a small red dial that allows the flow to be adjusted and save some electric power as well.

 The design of the eco-circ is really excellent.  The pump/impeller side can be easily separated from the involute/pipe fitting side.  This allowed me (really Amy gets credit for this idea) take the new motor and attach it to the Caleffi fittings (which are custom).  So I took half of one eco-circ and screwed it to the other half of a second eco-circ pump to get what I needed.  The "vario" pump was purchased from Sun Volt Energy (www.sunvoltenergy.net) for $179 which is an excellent price considering I paid $325 for the Caleffi pump.  Sun Volt got the pump out to me in just a couple of days which was great.  The image shows the two halves of the pump.

 As can be seen in the picture, the official part number for the "Vario" is D-38/710B.  I found the Eco-circ part numbers to be confusing.

  The Results:  This is the best part.  Using the dial, I could adjust the speed of the motor until I had 2.5 gpm flow as shown in the picture.  I give Caleffi credit for including this nice flowmeter into their pumping station design.  Without the flowmeter, I would have no idea what kind of flow I was getting.

   Now for the best part, connecting the pump to a power supply and the power supply to a Kill-a-watt, I found that the power used is only 9 watts versus the 50 watts used by the old eco-circ pump.  Can't wait to see if it works as well on sun-light power.  Think about it for a minute. 2.5 gpm for 9 watts!  Many home circulators require more than ten times the power to do the same job.  Well done Laing.

   The hot water tank still needs to be connected to the domestic hot water system.  Hope to do that soon.  A plumber is coming tomorrow to look at the system and another plumber said he would do it for $1100.  I would prefer to do this myself, but officially, only a licensed plumber is supposed to do the job.  The whole project has turned out to be way too expensive.  However, I must complete the project at this point to be done with it and get the benefits.

Furnance Duty Cycle

   The primary motivation for putting in the solar panels has been to reduce oil consumption and the ultimate success or failure will be judged by the oil savings.

    But measuring oil consumption is slightly difficult and very low resolution.  The truck comes to your house and fills the tank about 8 times per year. It is difficult to know how much oil is used in any given month and you can forget about seeing any consumption data on a daily basis in a way that is easily possible for metered products like electricity.

   However, I have found another way to measure oil consumption.  The technique has two parts.  First, the furnace supposedly uses 1.0 gallon per minute when it is on.  Secondly, there are data recorders (data loggers) that can measure when a motor is on.

   The data logger that I used is called a HOBO from manufactured by a company called Onset.  This is a great product.  You can log one year's worth of data.  It only uses one CR2032 watch battery, attaches to the motor with a magnet, and remotely senses the motor state based on fluctuating magnetic fields.  It has a USB port and the data can be downloaded to the HOBO software.  It is about $100 for the data logger and another $100 for the software. 

  What was a slight pain was parsing the data in Excel.  What I really want to know is Duty Cycle, or the percentage of time that the furnace is on in a given day.  What I start with is a bunch of time events that indicate when the motor turned on or off.  I spent a few hours writing a VBA macro in Excel to parse the data the way I wanted.  The biggest problem is splitting events that happen just before or just after midnight.  But the result is just what I wanted.

The chart is a little complicated so let me walk you through it.  On the horizontal axis is time, about one year starting at the beginning of heating season around October 7.  The black dots are data points for the duty cycle.  If the duty cycle was 50% it means that the furnace was firing half of the time.  I have almost a full year's worth of data.
   Since the data is a little noisy, I fit it with two curves.  One curve is parabolic and represent the heating season.  The second curve is linear and represents the summer season.  This gives a clearer representation of the two uses of the furnace 1) domestic heat, and 2) domestic hot water.  It seems reasonable to assume that the domestic hot water is fairly consistent throughout the year.  In fact, it looks like there is a baseline usage of about 5% or roughly 1 gallon of oil every day.
    The oil usage might rightly be broken down into three usage
1) Domestic home heating
2) Domestic hot water
3) Idle losses
Even if no one was in the house and it was summer, my furnace would still consume oil due to the old fashion "tankless" water heater.  The tankless heater requires the furnace to maintain temperature 24/7/365 just in case someone wants some hot water.

    It is difficult to separate hot water usage from idle losses so I have grouped them together in one group in the graph.  Hot water and idle losses represent about 40% of the oil consumed or 377gallons.  Of that, probably half is hot water and half is idling losses.  So a big win for the solar hot water system will be for it to make enough hot water to allow me to shut off the furnace in the summer.  If oil is $4/gallon, then 377 gallons/year means $1508/year, but I will never achieve that much savings because it is not sunny every day and I am not sure how to automatically shut the furnace off and I might also need to bypass the furnace to get this system to work, something I have yet to figure out how to do. Step-by-Step.

  For domestic heating, an estimated 555 gallons (60%) are used per year.  So perhaps I should have spent my money on a more efficient furnace rather than solar water heater system.  But then again, perhaps I can do the furnace upgrade in the future.

  The estimate shows about 932 gallons/year total oil consumption.  This number is quite good because in the 2009-2010 season I used 942 gallons, so the estimate might be within +/-5%.  The insight gained from the data logger information more than makes up for the possible +/-5% error.

   Hopefully in a year, we will have lower duty cycle numbers to share with you.

Up and Circulating

Once all the plumbing was in place, I was more than a little nervous about whether or not the system would hold pressure.  One bad solder joint could make my life very difficult.  So I set about the process of filling the system.

In order to fill the system, I purchased a 1/2 hp "jet pump" that is used for wells.  The pump would be used to draw water (or propylene glycol) from a bucket and pump it into the system.  Of course, like everything else, this meant taking a trip to Home Depot to figure out the appropriate fittings.  The inlet of the pump was a massive 1 1/4" NPT thread but the outlet was only a 3/4" NPT thread.  These would need to be adapted to "hose bib" fittings.    I found a 1 1/4" to 3/4" adapter so that the inlet and outlet were now both the same and I also found two 3/4" npt to 3/4" hose bib adapters.  Also purchased a couple of washing machine hookup hoses to connect the pump in to the solar pumping station.

  The water could then be pumped out of the orange buckets and into the system.  The fluid was then returned back to the bucket in one continuous loop.

     Unfortunately, I had two leaks. SIGH.  The first leak was between two of the solar panels.  It looks like I was not careful enough when installing the panels and one of the o-rings got pinched between the brass surfaces.  The o-ring was damaged and had to be replaced.  The second leak was one of the copper unions that I had placed above the hot water tank to facilitate service.  This union had a large open pore (void) in the surface where sealing was to occur (Thanks Cello).  So I purchased a new union from Home Depot for $17 rather than the $9 I had spent on-line for the other ones, but anyway it was replaced.
    Now to deal with the broken O-ring.  After having spent more than $3000 with Heliodyne, you might think they would have included a spare O-ring, but no.  Strike 1.  But should be simple enough to find a replacemtn.  It is a 1.250×3/32" o-ring.  So I go to Home Depot, Strike 2, they only have o-rings for kitchen faucets.   Go into work where there is a huge selection of o-rings.  There is a 1.250×1/8" but no 3/32".  Strike 3.  Drive to Sears Hardware in Ashland because I knew the Sears Hardware in Delaware (near where I formerly worked) had drawers full of o-rings.  But Sears Hardware Ashland doesn't have o-ring drawers.  Strike 4, but the Sears salesman does give me a tip to look at Ace hardware (which was closed at the time).  On the way home, I went to Lowes which also does not have o-rings despite the Lowes salesmen sending me on a wild goose chase. Strike 5 with four hours wasted.  The next day, I went to Lexington Ace Hardware near my house and purchased the needed o-ring for 59 cents.  Sigh.

   With the leaks fixed, I charged the system with water and it held.  Then I flushed the system with a water and TSP (tri-sodium phosphate) cleaner for several hours.   Next I flushed TSP out of the system with 20 gallons of clean water.  The jet pump moves the fluid at more than 5 gallons per minute.  Very impressive to see a 5 gallon bucket emptied that quickly.

   One small problem is that the flowmeter on the pumping station stopped working some time during this process.  The flushing had liberated some steel (or aluminum but not copper) shavings that got caught up in the flowmeter.  That required removing the flowmeter and removing the metal with tweezers.  Put the flowmeter back in and things were up an running.

Circulating on its own.

  It is all very well and good to use the charge pump, but the system should function with its own internal DC eco-circ pump.  First several attempts to do this failed.  There did not seem to be enough power coming from the solar panels.
     The process was very frustrating.  The eco-circ has its own built in controller that only takes as much power as is available from the solar panel and can supposedly run on as little as 8 watts.  Since I had a 20 watts of solar panels, it seemed like the pump should run.  The power from the solar panels was sent to both a charge control AND to the pump (switched through a relay).   My hope was that the charge control and the pump would each only take what they needed and share the power.  But this may have been a vain hope.  Even directly connecting the solar panel to the motor didn't seem to work.  I think there just is not enough power to get the motor started.  Even if the pump motor might be capable of running from 8 watts, perhaps it cannot start from 8 watts.
   So I needed a new plan.  One quick trip down to You-Do-It Electronics in Natick and I was back in business with a 50 W 24VDC power supply.  This did the trick and the pump started moving.  However, it was unreliable.
    Quickly I figured out that the problem was with air in the lines.  There are two air traps in the system which work great, except they can only do their job if the water is circulating.  Unfortunately, the water could not circulate because there was too much air in the lines.  Specifically, there was air trapped in the space where the motor impeller is located just before a check valve.  So there is a Catch 22.  The air traps cannot do their job if the water is not circulating but the water cannot circulate if there is air at the motor.

     By trial and error I found that by increasing the pressure  in the system (using the external charging pump) I could get the small circulator pump to start the water circulating.  The system has a flow meter with a glass window and massive quantities of air bubbles could be seen moving around.  Eventually, the bubbles worked their way to the air traps and could be purged from the system.  Then the some water was drained from the system to get the water pressure back down to about 12 psi.  All and all, I was happy to get to this point.  The system was holding pressure.  The water was circulating.  Not only is it circulating but it is circulating at more than 5 gpm (gallons per minute) which is twice the necessary 2.5 gpm.  Unfortunately it is taking 50 watts to get to 5 gpm, but hopefully it can get to 2.5 gpm for 25 watts.

    Clearly larger solar panels are needed so I ordered two 20 watt (40 watt total) solar panels from Amazon for $150 with $3.99 next day shipping..  Hopefully this will fix the issue with the pump.  I debated getting larger panels (like 60 watt total) but I really shouldn't need that much.


The Installation Tour

   So let me give you a tour of the installation now that it is almost complete.

The image above shows the South wall of my basement which contains most of the inside solar equipment.
1) Solar pumping station.  The front of this is the differential controller responsible for turning on and off the pump at the right time.  It is connects to thermistors (temperature sensors) on the solar panel and in the hot water tank.  Behind the controller is the pump and a large number of other components.
2) These Taco zone valves, when open, allow water (heat transfer fluid really) to flow to the hot water tank.  I doubled up on them to increase the amount of flow but in hind-sight this was probably unnecessary.  Although the connections to the valves are 1" the valve itself is probably less than 1/2".
3) These Taco zone valves, when open, allow water to flow to the heat dump.  Again they are doubled up.
4) This box contains A) charge controller, B) 24 V NiMH battery, C) 24 VDC to 12 VDC converter, D) some relays.
5) Some additional relays were needed to turn on the pump.  Unfortunately the controller is 12VDC but the pump is 24VDC so some relays were needed.
6) Expansion tank to take up the extra fluid when the water expanses when heated up.
7) These two pipes connect the pumping station to the solar panels
8) These two pipes connect the pumping station to the hot water tank.

  The picture above shows the 1/2 hp jet pump used for charging the system with fluid.  The fluid comes out of the bucket and is pumped into the solar system.  About 10 gallons is needed to fill the system.  The charging system is temporary and will be removed once the system is commissioned.

     The jet pump connects to the fill and drain ports on the solar pumping station (shown above) using garden hoses.

  Looking at the installation from another angle, we can see the solar pumping station (1) on the right, the piping (2) above, and the hot water tank (3) on the left.

       The overhead piping needed to be supported.  But most brackets would crush the insulation.  So I cut out a piece of aluminum (8x4"), painted it black, and placed it underneath the bracket to spread the load.  I also painted the bracket both black and white to match the insulation and ceiling as needed.
  

   On the other side of the room is the hot water tank.  The 80 gallon tank is manufactured right here in Massachusetts by Heat-Flo which is pretty cool.  There are a couple of nice things about the tank.  Firstly is that it is made of stainless steel which should assure a very long life time.  Secondly, all the connections are on the top of the tank which makes for a very clean installation. 

   The connections through the top of the tank were made through copper unions and full port valves. This setup allows the tank to be isolated from the rest of the system for servicing.

The wire for the thermistor was routed down the front face of the tank and secured with cable clamps that I pop-riveted to the plastic outer shell of the tank.

  Lastly, the solar PV panels were temporarily attached to the hot water panels using some 2x2" pressure treated lumber.  I felt there was a good chance that they would need to come off again, so I didn't attach them more permanently.  They will soon be replaced by larger panels and if those work out I will get some aluminum extrusions on which I will mount them more permanently.

  Next step, see if I can get Sweet Plumbing in to connect the hot water tank to the domestic hot water supply.