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Thread: Solar energy for beginners

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    Canada Avalon Member TEOTWAIKI's Avatar
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    Default Re: Solar energy for beginners

    Quote Posted by Anchor (here)
    Quote Posted by TEOTWAIKI (here)
    At the heart of my system is a raspberry pi, connected to a couple arduinos; one via usb and another over wifi.

    One arduino has current and voltage inputs (aliexpress) so I can closely monitor in real time the incoming amps, voltage, watts of the generation system. I also have a Solar Analyst with shunts on the main battery feed and the charging current back to the battery.
    It sounds like you are having a lot of fun - are you coding up your own control system?

    Solar trackers are a double edged sword.

    They are a blessing because they will keep the panels close to a perpendicular plane with respect to the sun "rays" and therefore maximize the efficiency, this is useful if space is at a premium. The downside however is the increased moving parts, points of failure and maintenance. Commonly trackers only operate in one axis (azimuth) and you manually set the altitude depending on the season, less commonly they do both.

    Trackers used to be a good idea when solar panels were very expensive and/or you didn't have a lot of space, but if you have the space, static arrays are more cost effective now and there are no moving parts so there are fewer things to worry about maintenance and reliability wise.

    In a marine situation, there are more reasons to go with trackers because you probably don't have a lot of space for panels and also as the vessel moves around and changes course, the trackers can compensate and keep the alignments optimal. The control system just needs to be aware of where it is, your bearing, and what time it is.

    You talked about doing something with excess power - can you explain more why you need to do that? The reason I ask is that with solar you don't have to do anything! You can just float charge the batteries and in doing that the solar charge controller will take as much available power from the panels to accomplish that and simply disconnects from the rest. So the power taken from the solar harvest is the sum of what is required to float the batteries together with any loads are being drawn from the circuit and this is adjusted from moment to moment at high speed.

    The problem of what to do with excess power arises from wind turbines (which are a good idea to have in a marine context). For these, many turbines do need to keep the generator optimally loaded to control the turbine speed and prevent it from going too fast and destroying itself. This is done with loads that you present - or if that is less than required - the power needed to brake the turbine is diverted to a dump load - essentially a heater.

    Anchor..
    Anchor,

    Yep, I programmed the control system using python for the Pi and C for the arduinos.
    The Pi supervisors the power system, runs the autopilot, monitors the weather. It has a touchscreen which displays the system data using numbers, graphs and selects the right map for the lat/long and displays position and tracks. The main arduino has an neo6m gps attached that gives lat/long, date/time, heading and speed; everything the Pi needs to calculate the position of the sun. Sensors for temperature, barometric pressure, rudder position, wind heading and wind speed are wired to a second arduino.

    I have a Tesup wind turbine in the system and its controller has a dump resistor exactly like you said; but I don't really want to dump watts that could be used to drive the boat or cook a fish. I view the solar panels in the same way; once the battery is fully charged and the panels are still harvesting power, why just trickle charge a battery when you could be using the excess power (power available from the panels that is being rejected by the MCT) -- to move the boat forward if the wind isn't blowing?

    As far as the solar tracker, you are correct that there is VERY limited space on the boat and being a sailboat, the orientation to the sun is always changing. The studies show a tracker can produce almost 50% more power versus non-tracked on land; so on a boat I'm guessing each panel will produce twice as much (or more) if a solar tracker is used but like you said it is at the expense of complications; servos, bearings and what not.

    A sailboat offers a lot of advantages as a bug-out vehicle. The rain falls into your sail and is funnelled to the rainwater tanks. An emergency food supply is right underneath, no fuel is required and the earth is 3/4 water

  2. The Following 7 Users Say Thank You to TEOTWAIKI For This Post:

    Anchor (19th November 2022), aoibhghaire (18th November 2022), Bill Ryan (18th November 2022), Brigantia (19th November 2022), I am B (18th November 2022), palehorse (24th December 2022), Pam (18th November 2022)

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    Avalon Member palehorse's Avatar
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    Default Re: Solar energy for beginners

    Quote Posted by Brigantia (here)
    Wow - if I had a large garden and a lot of money I'd get one of these for underground storage:

    https://engineerine.com/groundfridge...structure-for/

    Attachment 49927

    That's awesome, but perhaps you could build a storage room or transform the basement (if you have one) into a food storage.

    but it can go both ways, a clean room storage with all the food just lying there or it can be any room (not necessarily airtight) and the food be preserved already, for example:

    - in cans
    - in myler bags
    - in glass jars (like pickles)
    - as smoked meat
    - as sun dried meat

    The claim that any underground food storage "must" be airtight super sealed does not mean anything, it is a marketing strategy for these companies selling their products for a premium price.

    Smoked and dried meats were common sense centuries ago ( still a bit nowadays ), there was no other means to preserve meat in a long term.

    Just trying to think as natural as possible.
    --
    A chaos to the sense, a Kosmos to the reason.

  4. The Following 2 Users Say Thank You to palehorse For This Post:

    Brigantia (24th December 2022), Richard S. (25th December 2022)

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