Off Grid Home Forums Technical Discussion Generac Generators/Transfer swich and MSW inverters

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    I purchased a Generac 7 1/5 KW propane generator and transfer switch sytem thinking at some time of maybe getting grid power into our place but we have changed our mind and will stick with an off-grid system but the Generator is all hooked up and supplying my power to the house temperarlly until I get the off-grid solar and wind sytem up and running. My question is can a person simulate the 230 hydro line power by providing the Generator brain module controller with another source of power from a MSW 220vac inverter to be able to signal the controller to control the transfer switch (once the 220 power drop out) to switch the power to the Generator power??

    And another question I have can a person use a DC charger instead of a battery to power the DC side of a MSW inverter for test purposes keeping in mind the amp draw with out damaging the inverter??

    I will also be thinking of using a transformer between the Inverter and house panel to provide isolation and a good grounding system. I will have to live with the parasitic loses which the transformer will introduce but I like to see some isolation between MSW inverter and House.

    Any suggestions out there would be appreciated.

    Thank you



    Why make it complicated? Simply bypass the transfer switch. ‘Fooling’ the transfer switch is going to get complicated because the transfer logic often looks for power quality so you cannot use a cheap MSW inverter. It has to be a pure sinewave inverter. And to what end? You say the generator is running your house now.

    Reading between the lines, it sounds like you anticipate using some kind of -grid-tie solar system ‘kit’ which is connected as AC power source which is selected by your transfer switch, when the sun is shining. I have been doing off-grid power system designs ever since I stopped working for Xantrex (statpower) some 10 years ago.

    Your approach sounds overly complicated which means overly expensive not to mention complicated and more prone to problems requiring time consuming trouble shooting. I could probably help you but this forum text window is too constraining with its tiny text size. I word with CAD converted to PDF drawings and WORD documents. About half of my customers require 230V 50 Hz systems. A recent system design built in Turkey had to be examined and approved by Lloyds of London insurance before construction began


    I am living in canada were we have 60 hz system and grid power is 230vac/115vac split phase.

    The Generac system control module needs 220vac power to operate the generator maintenance reading and warning light system eg. teperature,battery,oil preasure etc. but one can run it on manual like we are doing (with out the module readings}now but I also have to use a seperate battery charger to keep the start battery banged up because the one in the generator runs from one side of the (hydro side) which can also be run from an inverter (??) like I want to and it would also be nice to have the generator automatic back up if I am not there to do the manual switching (wife at home) and I still need to use a box and cct. breakers to do all the connections. So if the switch could be contolled by the controller it make my life easier. The controller only has a 220 transformer to reduce the power to 24v to run the controller and to signal the transfer swtch to operate when that 220 fails. I all ready have a MSW 5000 watt 220vac 2 wire inverter which I am going to put a 220 to 110vac transformer to power the house as I do not need 220 into the house as all major appiances run off propane. The house will only be reguiring 1500 watts at any one time, most off the time around 550 watt as all out lighting is LED or low power floresent

    the largest items being micrwoave,washing maching,vacume cleaner,tv,computer etc. ( not all running at same time)

    The inverter runs off 24 volt 500 watt hour Battery bank which is charged by 1000 watt solar panels and 500 watt wind turbine. A 40 amp 24 vdc charger run off the generator pwr is my back up.

    I hope that clears up some of thinking????


    Musselbeach? Would that by chance be the one near Uklulet ?

    I’m thinking it would be convenient to use the genset as the ‘grid’ power inlet. When this shuts off, the transfer switch toggles over to solar, which would connect to genset input. When solar develops sufficient power a simple relay could signal the transfer switch to toggle back to disconnect the genset. Another relay could signal genset stop as needed.

    Generally these automated transfer switches are set up to start genset when grid power fails. However you do not have utility grid connection.

    You could also provide control circuit board power from your battery pacck so it retains power at all times.

    Now I understand your comment about a transformer however it is not to provide good grounding but to deliver 120V for utility 120V. I do exactly the same on my boat systems destined for american owners who insist on using american appliances while overseas.

    It also comes in handy off-grid where the deep submerged pump needs 230v to start. The uncle has such a system on his 350 foot deep well on the homestead. Everything else except the dryer and jacuzzi is 120V.


    Yes we own Mussel Beach property and I have develpoed the campground from scatch as my retirement project for the 16 years, my daughter and her husband is now managing the campground shown in Our web site.

    which is near Ucluelet on the north side of Barkley sound, have you camped with us?

    Thank you for your Idea, that also makes good sense. I will have to rethink the syetem in that way?? I have thought of using 12 volt dc solinoids to switch inverter DC input power Remotely (positive lead) off at night so it does not consume battery power sitting idle. I am hoping that the generator will not be used that often except to bank up battery power when the does not shine for many days and no wind also am planning to run a hot that I am planning purchase.

    I collest rain water off our metal roof (6000 gals storage) to provide us with water which only uses a 12volt dc pump giving us 35 lbs preasure very simple system.


    Yes we camped there. In fact we still get a chuckle out of remembering. After we got the camp set up and dinner cooking on the BBQ my daughter freaks out

    Daddy Daddy ther’s a bear! Well gee! its a small black bear probably just a yearling and its 1000 feet away upwind. The bear is slowly ambling along the shore flipping rocks looking for dinner. If it keeps following the shore it isn’t likely to get closer than 100 yards and still upwind. But my daughter (raised in town) is still freaking out. Sure enough the bear didn’t seem to notice us and eventually we had our hamburgers in peace.

    I have had bears leave muddy paw prints on my RV door so this wasn’t even a close encounter for me. My daughter who grew up in Toronto is more of a suburbanite. I now live in Hazelton east of Prince Rupet. Spent five years in lower mainland while working for Xantrex.


    Yes we have quite a number of black bears living on our property a least two mothers have a pair a cubs every year. Were you in Engineering in Xantrex? I understand they have a very good line of inverters but quite expensive.

    I have been looking at appollo

    It appears to be similar and a little less money.

    But I thought of playing around with the MSW inverter as their cost is a 1/4 of the price and can be a recycled if they give trouble with out costing you much. Did you ever try and put a transformer directely on the output of an inverter and have a look at the wave form ( I would not suspect it would change much)and or used a charger as an DC inverter supply for test purposes??

    I currently spend our winters on Saltspring Island as my parents are still alive and we have not sold our house.

    we are in the process of having a 28 square foot (2 floors) garage/storage built on the mussel beach property next to our house, it is located about mid property directly above the water front on top of the ridge were the campground road is very close to the water edge if you can remember the area.

    I am going to have to supply power to it as well.

    By wiring the Generac Generator transfer switch the way you suggested would mean removing the module and rewireing the generator as 12dc volts runs from the module to the transfer switch to operate the switching solinoids so I think I will first try using there wiring method. I could not get any info out of Generac as they said any sue of their system without grid supply and not hooked up as the instructions say avoids the waranttee. They would not even talk further even if a signed a waver.?? I also can not find info on the net for the model I have but they do have manuals for the water cooler larger models which I can get some info from.



    Ron I emailed you at the business address on website. Send me a number at which I can phone you. or can you retrieve emails sent to business website.


    Hi Elnav my email address is

    The web site one is for used for campground business but it would be forwarded to me in time as my daughter if away for a couple more days.



    Ron’s situation is by no means unique so I am posting some comments for the use of others. The first question can you use an MSW inverter to fool the transfer switch. That depends on the intelligence of the logic. Power line quality assessment is coming down in price to the extent it is cheap to include in the design. the reason being you do not want the transfer switch to toggle on poor quality power such as may exist during power system switching and fault clearing. Inverters that include integral transfer switches usually do not initiate a transfer untill 8-10 seconds after clean power has been restored.

    Much depends on the style of transfer. If it is seamless transfer phase matching has to occur first.

    I have seen first hand what happens when out of phase cross connections happen. The IGBT vaporize then explode spraying molten metal in all directions.

    Second thought. If the other alternative is OFF-GRID such as wind or solar there is no need to feed their output through the transfer switch if their output can be fed directly to the battery. Buying solar panels or 220V wind turbine such as grid tie uses is needlessly expensive.

    More details of the generac itself is neeeded.


    Of course you can simulate the hydro line power by providing the generator controller with different source of power from a generator to be able to control, can change the power to the generator.


    backup power generator


    Wow! I love that TSW3224! I have had twin com linked DR2424s for 14 years, with 115VAC charging from a Generac 4000XL (done manually). The DR2424s also have built in transfer switches.

    The thing I like about the TSW3224 is that it would replace both DR2424s with the 240VAC 180* out of phase I need for my well pump. It would take up half the space.

    I tried using the generac’s 230VAC output for charging, but it is a three wire system which was incompatible to the 240VAC 4 wire system. So when I am charging the batteries with the generac, I use the 115VAC instead and the pump won’t work unless I shut off the switch from the generac or just unplug the 12′ special cord.

    Originally a comparable SW4000 was more money ($23-2500) and required a step up transformer ($700) and a lot more room.

    With the TSW3224, it looks like the time to change is now!!!

    Oh, I had kind of bad memories of Uklelet in 1993. Advertized catch your limit of salmon and halibut. Stayed in an old freighter. Caught a total of 15 lbs of fish for a total cost of $750! Skunked out of salmon and halibut in that over-fished area.

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