Imagine being at anchor, floating easily at a pleasant watery location, not having run the engine for a few days – ah, quiet and tranquil. Imagine also now one of those cooler mornings when the engine-heated water tank has run out of hot (or warm) water. And now you’d enjoy a hot (or at least warm) shower before starting your day? Of course, we could run the noisy engine, and burn more Dino fuel. But that’s very wasteful (and not very good for the diesel engine to run without load – i.e. not going somewhere with the propeller.)
We have found a more economical and environmentally conscious way to make hot water, and a wonderful new addition to Fayaway: 400 watts of free solar power. This post will explain a bit about this installation, mixed with a few tidbits on methodology on solving and planning various challenges.
We purchased a pair of 200 watt PV panels back in April, adding to our pile of other equipment to be installed. Adding these panels to Fayaway first required installation/assembly of a bimini frame onto which the panels are mounted, and that would need to wait until she was in the water (less awkward, logistically, and away from unwanted attention at the marina). This week we achieved all these steps. And wow, it is exciting to liberated from being at dock or running the engine every other day just to keep the beer cold, charge our phones or… make some hot water.
Here’s how it works: Power comes from the sun to an “array” of two Peimar (Italian-made) photovoltaic (PV) panels, which pump out (up to ) 37 volts DC electricity. Raw power from these panels is funneled to a pair of Victron “Smart” MPPT charge controllers.
The charge controllers constantly monitor the battery conditions (temperature and voltage) and then optimize the amperage and voltage feeding to them. For example, if the batteries are near capacity, the controllers will raise the charge voltage (float at lower amperage) so to optimize the charge effectiveness. But if the charge is low, the amperage will increase to more rapidly increase battery charge. We have a separate charge controller for each panel not only to provide redundancy, but also to improve solar PV efficiency should a shadow (perhaps the backstay) cover one of the panels, the other will remain at full power.
The basic sketch below illustrates how we make hot water without running the engine (or being at dock for shore-power).
Essentially, our sun makes electricity via the PV panels, which charges the batteries that provide 12 Volts DC. Almost everything on Fayaway runs on 12 volts DC (VDC) – lights, pumps, refrigeration, radios, phones, and ipad chargers. But in the case of a few items we have that run on typical household power (120 VAC), we have an inverter. The inverter converts 12 volt power to 120 VAC. Hence, our water heater can now heat the water.
I digress again to explain how most technical and organizational details start out here – a quick sketch in my notebook. It may be a progressive series of scribbles, and some don’t come to reality, or just a few ideas for later, or a list to organize my thoughts.
When I needed to figure out how to cut the tubing for the bimini frame that holds the solar panels – out comes the notebook and pencil, to use a bit of rusty trig.
As another example, when figuring out how to map out storage location of items on the boat, out comes the notebook, on the next page I crudely illustrate the location of all compartments and storage lockers. It is quite a puzzle to fit most of life’s possessions into a 35 foot sailboat!
Ultimately, all this figuring and capturing of our sun comes back to making a comfortable place to live on Fayaway, including a nice hot shower on a cool summer morning!