Here is something I posted on another site, I hope you can find it useful.
[b:34a071bf96]Should you have a PTO generator or not?[/b:34a071bf96]
You are going to get a lot of people who will tell you that PTO generators are the best and a lot who will tell you otherwise, it really depends on use case.
[b:34a071bf96]1. Model of usage[/b:34a071bf96]
What kind of power needs do you have? Are you one of those people who need to have power 24x7 or are you just going to need it for a couple of hours a day? If you need power all of the time a dedicated standby generator is better. You are not going to want to have a tractor running through the night if you can help it. While it will run 24x7 you ideally would want someone checking on it once in a while to make sure everything is OK. If you are going to use it a few or several hours a day and then have times you won't need power I think a PTO generator is a very cost effective way to get power. Some people obsess about having power all of the time and they want to not even know they are off of the grid except for a little LED that comes on and lets them know that the generator is running while others just need something once a day to run the refrigerator and freezer and other than that don't care the power is out. Most are in between but there is going to be delay hooking up the tractor and you are probably going to want to not even hook it up for a small power outage that lasts 30 minutes.
[b:34a071bf96]2. Need of tractor[/b:34a071bf96]
When the power is out are you going to need your tractor? This also falls into number 1 above. The tractor can't run the generator while you are out plowing snow, moving down trees or some other need. If you are OK with the power being down while you are using the tractor, if there is a need for the tractor, then it isn't an issue. Do you have more than one tractor? Maybe you have one that generates power while you are using the other. When I lived in South Dakota and the power was out after a blizzard, there wasn't any rush to plow the driveway to get to the road, it was going to take a few days for them to even plow the road and no where to go until then. Some places power goes out because of the grid itself and you won't have need of your tractor, or not very much during power outages.
[b:34a071bf96]3. Power requirements[/b:34a071bf96]
How much power do you need? PTO generators are a cost effective way to get a lot of clean power. People forget that with todays appliances and electronics that they want clean power. There are times when a HVAC unit won't run even though there is enough power but it isn't clean enough. Ovens, refrigerators and other things have microprocessors in them and they may or may not handle the power some generators put out. I always recommend to people to get a until that has "clean power". Power is considered clean if it has total harmonic distortion (THD) of less than 6% (<6%). The funny thing is with todays global market, lots of electronics can handle different voltages and frequencies, for example the power supply on the back of my PC can take power from 50-60Hz and voltage from 110-250v. It will automatically take care of it. I don't recommend running your generator different than the standard outlet specs of your house, I only bring up the example to show that THD is very important and it is glossed over by some generator makes even though I believe it is just as important as voltage and frequency in the context of home backup. If you were just going to use a generator to run some hand tools like a skill saw out in the field where there isn't power, then it isn't near as important. Those tools can take some pretty crappy power and run just fine. As a side note, most PTO generators provide clean power.
[b:34a071bf96]4. Ease of hookup[/b:34a071bf96]
How hard is it for you to hook up? Would you ever be away from home and your wife, daughter, son needs to hook it up? If there is a need of them to hook it up can they do it? Are there a bunch of things going to be in the way of the generator that need to be moved before you can get to the generator or can you back right in and hook up easily. My wife and son also love to drive the tractor so they wouldn't have any issues backing the tractor up and hooking up for example.
[b:34a071bf96]5. What do you already have[/b:34a071bf96]
Do you already have a tractor(s)? How are you setup for fuel? If you want a standby generator do you have a large propane tank or access to natural gas of the correct pressure? Natural gas generators are hungry machines and they need enough pressure to run. They can't just be hooked up to your existing line, you have to get with your gas company to find out if you have access to the volume and pressure needed before you buy a generator. Propane, do you have a large tank? How often do you get it filled? If it is only for the standby generator you might be low on the list of customers to fill since you are not a regular. I did a lot of research of people who had backup generators during major power outages and if you are not a regular propane customer then you might not get refilled if the power outage lasts that long. Gasoline doesn't store great but it has a lot of energy in a little package and there are known ways to keep stored gas fresh if you take the required steps. Diesel stores even better with more energy in a smaller package, though it also needs steps to keep it fresh and ready to use when needed.
[b:34a071bf96]6. Cost[/b:34a071bf96]
How much power do you need and does it need to be clean? If you are needing a lot of clean power the cheap big box store model isn't going to cut it. They are not designed for clean power and they don't always handle running hours and hours on end very well. If you look at the generators that are up to clean power with the amount that a PTO unit can put out, you are going to pay twice as much or more for a stand alone until with the same specs as a PTO unit. PTO units are pretty heavy duty and are rated from long hour usage up to almost prime (when a unit is considered to be prime power it can be used as your sole power source, 24x7, 365 days) If you get a standalone are you going to be OK with another motor to take care of? With a separate engine it needs to be run every so often and exercised to make sure the fuel doesn't gum up in it as well as keeping the generator end healthy and happy. You should exercise your PTO generator as well but a PTO unit is a little more forgiving, most people use their tractors all of the time so they are in good running condition. Even a standby unit that runs itself once a month from natural gas is going to still need care. People do say they hate the idea of putting hours on their tractor but I feel that is what the tractor is designed for. Very small diesel tractors are rated for thousands of hours before rebuild, say in the 5K range, now that is going to be very dependent on how well you keep up with your service intervals. But if you are crappy with your service on your tractor you are probably going to be crappy with your service on your stand alone and it isn't going to work well for you either. If you have a larger tractor you are looking at the 10K+ hours before rebuild. Point being 99.9% of the people with a PTO generator are not going to put a significant dent in their tractor service life.
[b:34a071bf96]PTO generators and where are they made[/b:34a071bf96]
This list is from what I have researched in 2015, things could change, maybe already have.
[b:34a071bf96]BaumaLight[/b:34a071bf96]
These generators are Italian heads made by Mecc Alte. They have clean power.
[b:34a071bf96]Harbor Freight[/b:34a071bf96]
Chinese made, unknown power quality
[b:34a071bf96]IMD[/b:34a071bf96]
These generators are Italian heads made by Sincro. They have clean power.
[b:34a071bf96]Northstar[/b:34a071bf96]
These generators are Italian heads, unknown make. They have clean power.
[b:34a071bf96]Voltmaster[/b:34a071bf96]
These generators are Italian heads, made by Mecc Alte. They have clean power
[b:34a071bf96]Winco[/b:34a071bf96]
10Kw and 15Kw, these generators are Italian heads made by Mecc Alte. They have clean power. Special note, these want 515 RPM at the PTO and not the standard 540 RPM. Your tractor might not make as much HP at the lower RPM which may or may not be an issue depending on tractor/generator/power draw sizing.
25Kw are made by Winco in the US, power is said to be clean but is measured at THD <8% which is outside of the definition of clean power. I would classify it as marginal.
Most others
If it isn't on the above list it is most likely made in China.
From the ones I could find of the major brands, pretty much all of the smaller generators are made in Italy or China. Mecc Alte and Sincro are very highly regarded European brands and make from very small to extremely huge generators. The American made generators seem to be in the larger sizes and power quality isn't always clean. Though the large sizes are more for running more industrial type of loads where a lot of times power cleanliness isn't as important.
Standard operating procedure is an American/Canadian company buys a gearbox and generator head, puts them together, creates their own little power distribution box to go on top of the generator head and sells it.
I hope this has helped a little, it turned out a little longer than I thought it would.