SOLAR vs All The Time and Trouble
and
Running Costs

Solar is far form being without running costs if one is talking about an off grid/ standalone system.

Batteries,  inverters and chargers all have limited lives which must be amortised.
Members here have calculated battery costs over useful life and come up with monthly costs.
The initial setup cost of a solar system is also a number of times higher than the setup cost for a generator.

Fuel costs for a genny are often offset substantially by the use of wsste oils.

I love solar, I just picked up a bunch of 405 w panels ( didnt even know they made them that big and hope to get more tomorrow) BUT, like anything, they have their limitations and proclivities.

I have never heard of an offgrid solar setup that did not have a backup genny but loads of gennys without solar.

For most, I think the ideal setup is a combination. Large solar array, modest charger inverter,  small battery bank, and a very healthy genny that can carry all loads with ease, including things like power tools and welders.

Solar is still going ahead quickly. I bought a heap of 250w panels 6 months ago so i could standardise and upgrade all my smaller wattage panels.
In the last 3 weeks I have picked up nearly 7 kw of  360 and 405w panels, all brand new, all for free. Seem like the 250w panels are soon going to be as obselete as the first 175s i bought  used about 4 years ago.

I have room for the new panels i was saving but as these are all new and compliant i think ill put them up and just replace the others as I go.
Probably going to be a narrow window between the weather being cool enough to get on the roof to put them up and the winter fall off when they are most needed.

My idea is to have a good solar setup in place if i ever want to go off grid and a complementary gen setup to go with it.

By the way thanks all for the input.

Glorks cautious approach

Glorks cautious approach to this hypothetical proposition is well taken. It could easily backfire into a smoking Extravaganza.

     The diodes I have in mind have a back-flow of 1600 volts but I wouldn’t trust even that. Fuses (not breakers at this time) too protect the components.
     
     This application is a sawmill powered by a diesel. Since it is only under a load about half the time because I am  messing around getting ready for the next cut I idle it down. The hydraulic system therefore idles at 300 PSI and is variable under load depending on the log and condition of the saw and can go as high as 1500 PSI. Much beyond that and the relief valve opens.
     
  The numbers are based on the 30 HP DC motor running under full load. Crude calculations indicate the sawmill needs about twenty HP max, I empathize crude but probably close. I based that on a formula of hp/hydraulic pressure. So realistically the DC motor might never reach full load though I would like to have a good safety margin.
 
That link is a nice easy to understand explanation of what an accumulator is and does. Basically a hydraulic flywheel. Looks like a properly designed system would be better than a mechanical flywheel. Unfortunately this simple hydraulic system is about the limit of my knowledge concerning hydraulics. What to expect beyond that I don’t have a clue.
         
A couple things I have considered is a flywheel mounted on the saw shaft to carry the hydraulic motor through that initial sudden load when the saw hits the log but it would have to tuned to sync with the system.   
   
I thought about rigging up say a five HP electric motor with an electric clutch that would be connected through belts to the saw shaft. As I pull up the diesel rpm the clutch activates and away I go. That might work.   
   
I am much more comfortable with electricity. I thought about the two generators (or twenty 12 volt batteries) long before I decided to go hydraulic but the concept seemed a bit too out side the box compared to a simple hydraulic system.

If I were rich I would most certainly go battery.

Not sure what you mean by (allowing it to sync and freewheel with the mains when it is out of use.) EdDee.

A generator connected to the bus can be brought up to just the bus voltage but no more and it will float. That is it will not add any current to the bus until the governor is tweaked a little like EdDee said.

Would the big engine running as a float be more efficient than running it at a idle?

I can get around 8 HR of sawing for around four gallons of fuel give or take, haven’t seriously checked that. I just remember looking at the amount of lumber sawed and the fuel used and being impressed.

Taking this to a serious level can’t ignore what has been posted. Forget idling, forget two engines, much more practical rig up the larger engine and go from there at a constant 1800 RPM. If the big engine can’t do it then add the smaller one.

Some 4 cylinder Volvo engines used a distributor mounted on the camshaft end. The timing could be advanced or retarded by rotating the distributor.

Pretty much ALL  pre computer / electronic engines had a distributor and rotating it was the way you set the timing.  Even the early electronic ignitions had a dizzy  but replaced the points and condensor.  I did a number of conversions with kits that you put a slotted disk and an optical pickup in the cap to replace the points and condensor. They worked very well giving a noticable performance boost and were no maintence.

I take it you havent had much to do with petrol engines?
Either that or you are a lot younger than me !  Everything had a dizzy when I  was young.  :0)