What generator to buy?

System
System Posts: 2,511 admin
in General Solar Power Topics #1
Hello all.  I am asking this for a friend of mine who  has just built an off-the-grid home and wants to purchase his first generator.  His needs to run a few lights and a radio or two, but his  big power use will be for air-conditioning.  He has the mini-split type.  One compressor outside with 2 or 3 heads in the house. 

The specs on the AC:

48,000 BTU
4,700 watts
single phase
220 volt
60 Hz

What brand generator and size do you think I should advise my friend to buy? Budget is an issue, so costs should be kept to a minimum.

I know my 5.5. Honda will not do the job.

Thanks for all your help.  Pompano

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: What generator to buy?

    if the generator is for just an occasional backup run nearly any with the capacity to run everything will do, but for those that are meant to run regularly a lower rpm generator would last longer for him, but it will probably cost more initially. as to the capacity in watts that's hard to say, but it is the surge watts that you need for startup on the ac. see if you can find somebody that would be willing to bring or allow you to bring a higher wattage generator to the site to see if it would handle the startup surge needed by the ac. btw if buying the high rpm type (3600rpm) generator then get an even higher wattage so that you're not overly taxing it and taking its lifespan away too fast.
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  • arcandspark
    arcandspark Solar Expert Posts: 63 ✭✭✭✭
    #3
    Re: What generator to buy?

    VERY IMPORTANT INFORMATION: I strongly suggest you purchase a PRIME POWER generator and not a STAND-BY generator. Prime Power is built to run 24 hours a day, Stand-By is build to run a couple hour a day. I have a friend what has had nothing but trouble from his Kohler 22Kw unit because the saleman told him that a Stand By generator would fill his needs. The service rep for Kohler has been out to his house seven times in one year. The generator has shaken its self apart. The main front motor mount bracket cracked, the covers on the electrical boxes all the mounting screw tabs have cracked from vibration. The two main generator shaft bearings had to be replaced. The service rep overheated them and burnt the grease black that was inside the new bearings. Every shut off sensor on the unit has been replaced twice, oil pressure, water temp, you name it. The bottom line that all the service reps tell us is the unit is a Stand By unit and not a Prime Power unit which is built to run 24 hours a day. Also these service reps say they would only purchase an Onan unit and not a Kohler unit for what its worth. Second item I would only purchase a low 1800 RPM and not a high 3600 RPM unit. Third if you can afford it get one that has an alarm panel that shows you what sensor is causing the problem, that way you can by pass it yourself instead of paying for a $200 service call to have the technician connect his computer and end up buy passing a bad sensor until the replacement sensor comes form the factory. Just my two cents. Sounds like you will need an 18Kw to 22Kw unit to be on the save side. Stay away form Genrac systems, their price is cheap, and so are they, bottom line you get what you pay for.  (arcandspark)
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  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    #4
    Re: What generator to buy?

    Very good advice arc, obviously you've played the game a few times.
    Larry
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  • arcandspark
    arcandspark Solar Expert Posts: 63 ✭✭✭✭
    #5
    Re: What generator to buy?

    I just started installing my third off grid system for a couple that are currently living in a tent. BELIEVE IT OR NOT. Taking a shower from a plastic bag hanging in a tree. Yah, I laugh myself. They wanted the cheapest system money could buy, so I told them to find someone else to do the system. Finally they asked me what would I suggest. I put together a Trace DR series 2400 watt inverter with four Trojan batteries. I found three that were never used, new, I got them for $100 for all three. Just have to purchase a fourth. I had an 8000 watt generator that had less then 2 hours use that was my spare. The one thing I did not like was my generator is manul start and 3600 RPM. I just got lucky, just purchased an Onan 5000 watt electric start, 1800 RPM two cylinder unit for $550 from E-bay, the guy is local so I was able to go listen to the unit running, what great deal. So now I get my back up generator back, and they get a much quiter, easy to start low vibration dependable generator and for $300 less then I sold them my unit for. Plus I feel much better about the system. Next step will be to add some solar panels, but the prices seem to be going sky high, what up with that???  arcandspark
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: What generator to buy?

    If you are a doit yourself kinda guy and want an low cost slow speed generator 650 rpm you might lurk at this site. http://listerengine.com/smf/index.php. I have a listeroid and have used it on several ocassions and have found it to be cheap to operate and can be made to operate very quietly. I pulled a 11 amp load on 220v for a week pumping water and it used .275 gal diesel/hr. They have a long life expectancy compared to a 3600 rpm gas job. But HEAVY!
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