Removing old solar thermal collectors

5 new 375W solar PV panels

A few weeks ago I completed the DIY installation of a mini split heat pump system in my workshop.  The system essentially replaces the solar heating system I built that used to use four large 4' x 8' solar collectors on the south facing shed roof of my workshop.  

I had installed the solar heating system 20 years ago and it had offset the use of propane over the years.  But that system could not begin to compare with the efficiency of electric heat pumps, and it is my goal to get off of fossil fuel as much as possible. The system used a few hundred gallons of propane last year.  Over the years I had learned to optimize the use of that system which originally used over 800 gallons a year, in the last two years it has been below 300 gallons.  You can see historical records of my propane consumption on this page of my blog.  The problem with fossil fuels is that their prices are unregulated and the cost of a gallon of propane has nearly doubled over the last 20 years.  

The propane tanks will remain in place to feed my automatic standby generator which is a necessity here in rural Maine.  Eventually I hope to replace that with a battery system since I can run that generator up to 7 days cumulatively in any given year due to extended power outages from storms etc.

The new REC brand solar panels are rated at 375 W each with a total theoretical maximum capacity of around 1800 W.  So far, I am seeing a maximum output of a little over 1400 W at noon at this time of year.  I don't have enough energy data for the new heat pumps to know whether this will completely offset the energy required to operate them.  But I am hoping it will.

 

mounting rails installed

inverter installed

I purchased a complete kit from the altE store in Massachusetts.  I simply called up my account manager, Ben and asked him to spec out a system that could produce close to 2000 W and cost less than $2500.  He specified everything that I would need including every single nut and bolt and it came in at around $2000.  I drove down to Massachusetts (a three hour trip) with my friends pickup truck to get all the equipment.  This includes five brand-new IQ7A micro-inverters made by Enphase.  These are state-of-the-art seventh generation devices that convert the solar panel power to 240 V that feeds right into my building.  (My original system used the M190 model inverter which was their first product over 10 years ago and 8 of those 30 units have failed over the years but were replaced under warranty).

I am so familiar with installing systems like this that I didn't glance at any documentation because it is so simple and plug-and-play for someone with my experience. 
The sequence involves:

• installing mounting rails
• mounting the micro inverters to the rails and connecting them to the umbilical
  
• running wire from the breaker box to the roof
• Mounting and connecting the solar panels

What could be simpler!

last year my solar power system provided all the power for my property from June through October. you can see historical statistics of my solar power system here.  I'm hoping these added panels will get me close to net zero.  Time will tell!

Here's a video I made about this whole project:

 

I installed another heat pump, this one for my workshop

 

I have installed a multi-zone heat pump for my workshop.  This was another DIY MrCool installation similar to the one I did for my house back in March except this one is a bit larger and has two interior air handlers, one for my office, and one for my downstairs workshop space.  It also has connections for a third air handler if needed. 

One of the slightly annoying things about these DIY packages is that the line sets that connect the interior to exterior units come in fixed lengths of either 16 feet or 25 feet.  I ended up with far more than I needed which explains why it is all coiled up against the wall next to the unit in the picture above.  It's not the worst thing in the world.  I only needed about 12 inches between the condenser and the interior air handler, and had to coil 16 feet of line outside, I imagine this compromises efficiency slightly, but I'm not too worried about it

I mounted  the condenser high on the wall under my carport.  This will keep it out of the heavy weather and is over 7 feet high so I can park underneath of it.  The installation was relatively simple, I just needed to cut a couple of 4 inch holes through the wall to run the plumbing through and everything else was just mounting parts inside and out.  The instructions are clear and very comprehensive, but having installed one of these already, I barely needed to look at them this time.  

The condenser is very close to my circuit breaker box inside the building so the 240 V wiring was quite short and easy to do.  The only challenging part was getting that huge heavy condenser mounted on the wall brackets.  I borrowed my friends pickup truck and he and I lifted it in stages onto the truck bed and then up onto sawhorses and so on until we got it high enough to lift it onto the mounting bracket.  I actually used the pickup truck as a raised work surface for all of the final connections and wiring, it was really convenient to be at the right height.

Here's a photo of the small air handler in my office which is more than sufficient for this small room and heats it up quite quickly (and also cools it handily in the summer).   

Downstairs in my workshop the large air handler mounts right near my wood stove which is my backup heat source.  

This system cost me almost exactly $3000 in parts and I expect to get a federal tax break of $300 per installed heat pump which is a real plus.  If I had to pay someone to do this insulation it would've cost way more than double what I spent.  Probably over $8000.  While this type of installation is not for the faint of heart, anyone experienced with building construction and wiring should be able to do it without too much trouble.

I have decided to take down the solar thermal heating system that I designed and built 20 years ago since it is no longer needed and is certainly not as efficient as heat pumps are.  In my next post I will show the process of removing the solar collectors and replacing them with 1800 W of solar PV panels which should be more than enough to offset the power consumption of these two new heat pumps.