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Home made solar generator hybrid

Discussion in 'Off Grid Living' started by oil pan 4, Jun 3, 2016.

  1. oil pan 4

    oil pan 4 Monkey+

    I build my self a portable highly mobile solar hybrid generator.

    I knew this generator and ones like it suffer from catastrophic fuel consumption (the particular one uses .77gal/hr at half load and around .5 to .66 gallons per hour at light to no load).
    That is perfect for me because I needed a fairly strong generator to run welding equipment and I wanted to to build a cart to put it on, give it more fuel capacity, put a huge battery and pure sine wave inverter to save on gas and run time.
    For the current solar configuration I am running Morningstar prostar PWM 30 amp solar charge controller and Morningstar tristar MPPT 15 charge controller.
    Two 80 watt solar panels (4 to 4.5 amps per panel).
    To quickly replenish the 100ah batter my home made 240 volt powered odd voltage battery charger (supplies 16 to 19 working volts like a "12 volt solar panel"), this hooks into the Morningstar to supply up to 20 amps in place of or in addition to the solar panels.
    The 240v powered battery charger produces up to 27 amps.
    The Morningstar 30 amp PWM and 15 amp MPPT work great together.

    The inside of my 240VAC powered 12 volt battery charger.

    I didn't go cheap on the charge controllers.

    Welding the solar panel hinged rack.

    Look no hands.
    I pulled the battery charger off to install a second rectifier and heat sink.


    The only thing different now is the morning star 15 amp MPPT is covering where it says "watts" and a fuse block is covering the number "10,500" and the switch for the battery charger is on top.
    The only planned additions I have are a Hz meter, amp meters for the solar panels and a fuel pump so I can pump fuel out to the lawn mower so the fuel doesn't sit in the tank and go stale.
    Last edited: Jun 22, 2016
    kellory, Tully Mars, AD1 and 5 others like this.
  2. UncleMorgan

    UncleMorgan I eat vegetables. My friends are not vegetables.

    Might try building one of those on spec. Could be the start of a side income. Sounds like a lot better rig than off-the-shelf.
    Ganado likes this.
  3. AD1

    AD1 Monkey+++

    Nice welding [chopper]
    Ganado likes this.
  4. oil pan 4

    oil pan 4 Monkey+

    That generator new is about $1,000 and with the minimum solar kit, 1 panel, 15 amp Morningstar tristar MPPT and the 100ah AGM would cost about an additional $600. As shown, with 2 panels, 2 charge controllers and 30 amp battery charger it's more like 1000 on the solar side.

    But I bought this generator from lowes warranty turn in junk pile for $100, all it had was bad exciter brushes.
    kellory likes this.
  5. Tevin

    Tevin Monkey+

    I don't quite follow. Is the solar to provide supplemental power to the welder and reduce fuel consumption, or is it to power small loads without having to run the generator?

    I do some welding myself and know it is an inherently inefficient process. You need a few thousand watts just to push a simple stick welder; having an extra 160 watts of solar (max) is not going to make a meaningful difference on your fuel consumption.

    The other issue is that your automotive battery charger does not put out "real" DC current. It produces pulsating positive AC. I'm not sure what this will do to your PWM controller (which expects to see pure DC), but I bet it's not good. Your inverter will not like it either, and the battery is not enough of an isolator to cancel the effect.

    If you put an oscilloscope on the output of the controller while the charger is on, you'll see a hot mess. You're essentially using the charger as a power supply, which is a big no-no.

    Have you used this setup long term? I think the PWM controller and the charger will fail prematurely, possibly the inverter as well, and you will not see any measurable fuel savings.

    I'm trying to be constructively helpful without whizzing all over your idea, so I hope my comments are taken the way they are given.
  6. oil pan 4

    oil pan 4 Monkey+

    I put in a 100,000 micro Farad capacitor in to smooth out the pulsed DC coming off the rectifier and checked the DC voltage for pulsation with my fluke123 scope meter. The DC wave pulse variations were equal to about 0.1v. It puts out very good quality DC current. That charger i built is not an "automotive battery charger" not even close. It is a battery charger I cobbled together from junk I had laying around. It's a 350VA, 24VAC industrial control transformer with 240VAC hooked up to the 380VAC terminals. It puts out 22 volts open current and 19 to 16 volts under load to mimic the output of a "12 volt solar panel". That is why the battery charger is wired into a solar charge controller.

    My home made battery chargers job is to rapidly recharge the battery with up to 27 amps at night or during cloudy weather. It is not intended to power the inverter but I tried this scenario to test for weaknesses and test all possible scenarios. The solar charge controller prevents battery over charging.

    The inverter, battery and solar system is only used to run small loads. That way I am not running a 400cc engine at 3600rpm sucking down a half gallon of fuel per hour to charge some batteries, run small to medium intermittent loads such as power tools, run a laptop, charge a phone. It's actually sized to power a refrigerator while the sun is on the panels.
    That way the 7kw generator only has to run for big stuff like welder, plasma cutter or to power everything during bad weather.

    It saves a ton of fuel using solar to power small items. At one point I was using this solar system almost daily so I know it works. I have been using this inverter on this generator with a large battery for almost 3 years now, the solar was added about a year ago.

    The inverter is not tied to generator output, it is a 900w pure sine sand alone 120v inverter with its own receptacles.

    It is not a grid tie inverter if you were to tie a grid tie inverter into a generators output something always frys. Plenty of examples all over the Internet of this.
  7. oil pan 4

    oil pan 4 Monkey+

    The 15 amp Morningstar tristar MPPT is only used with the two 80 watt panels.
    The 30 amp Morningstar sunsaver PWM is used with my home brew battery charger, as a backup and to tie in with other solar panels. I have about 400 more watts of panels. There is also an Anderson connector so I can add a set of jumper cables and tie into a vehicles 12 volt electrical system.
    The whole idea is that it is small. Its one portable self contained high mobility unit made to save lots of fuel in low power situations.
    Really this mobil solar/gasoline generator is just a small part of a much larger modular mobile platform that I have already built.
  8. arleigh

    arleigh Goophy monkey

    The one caution I have in building a system on a generator is vibration.
    However, If yo've used aircraft grade wiring there should be no problem . automotive wiring is inferior and cannot tolerate the vibration for very long. ( air craft wiring has thinner strands = toleration of vibration)
    I learned this working on air compressors and boats and a few generators as well .
    Other wise I like why you've done, good job.
    My controller by the way is an old automotive voltage regulator, I accept the losses , because I am adding and switching in and out both charging and loads from time to time .
  9. oil pan 4

    oil pan 4 Monkey+

    Here I am testing the 240v battery charger and inspecting it with my flirI7 to check for over heating connections and components.
    Then I found the 25 amp rated bridge rectifier running a little hotter than I would like to see it at 26 amps.
    My solution, add another bridge rectifier and heat sink.
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