valhalla360 wrote:

Getting back to the generator disscussion:

We have a Yamaha 2400.

Purchase price: about $1000 a couple years ago.
Can't turn off the throttle (eco mode), but has a surge capacity of 3000 watts according to some sites (tested not rated).
Runs 8-10 hours normally. 5-7 with the A/C running. 1.5 gallon tank.
Oil changes and regular maintenance negligible (half quart of oil and a spark plug). Under $10/yr with 3 oil changes and a spark plug.

Solar/Battery systems: On our boat we have a pair of 55watt pannels (110 total) feeding the "dreaded" 6 volt golfcart batteries. I could probably improve it a bit by redoing the wiring and connections, but we are lucky to get 24 amp-hours out of the system (I'm not adjusting them 3 times a day). Not worth messing with as it serves our light duty needs (lights, water pump, 12 volt fans). Beware of the buy it and forget it approach with a solar/battry system. The batteries require regular maintenance or they will die a quick death and more importantly the batteries do wear out. If you are talking about a 6 battery bank with a 5 year life span at say $100/battery, you need to add $2400 over that 20 year life to cover the cost of new batteries. It may still work out cheaper than a small generator depending on how you use it but it isn't a free lunch (The less you dry camp and the bigger your power consumption the more the generator makes financial sense.)

valhalla360 wrote:

You may want to get a fresh "battery" in you calculator (sorry, I couldn't resist). 58 gallons @ 8 hours/gal results in 464 hours of run time not 300.

Good point regarding both systems needing new batteries, except there still it a major cost difference. While I have a pair of 6 volt golf cart batteries (one set that moves between boat and 5er) when they die, I plan to replace them with a single trolling battery. Assuming the same 5 year replacement cycle, that is 4 batteries vs 24 over 20 years. So instead of saving $2400, it is a $2000 savings.

This appears to favor the generator based on consumables. Of course over 20 years the generator may need repairs and other more expensive work. On the same token, things can go wrong with a solar/battery system (short circuits, vibrations damaging the electonic controls, an overhanging branch smashes a solar panel, etc.) Hard to put a number on these items as they are rare events that won't average out for a typical user.

A key point in the choice is how much you dry camp and how heavy is your power usage. We don't hesitate to use the generator for A/C and we also run it for TV, fans, electric skillet etc. I would say 4-10 hour/day and we are typically away from shore power for only 2-3 days at time. That combined with minimal consumption of 12 volt means the batteries get topped up most days.

Your pattern of usage may make the solar/battery approach make sense. For our use, a generator makes a more sense.

Snip:
So you run 300 hours per year approximately? At 8 hours average run time that makes about 58 gallons of gas? Costing 116.00 @ 2.00 per gallon? And perhaps $100.00 for purchase? Call the total per year with oil changes $226.00?

You still need batteries with a gasoline generator--and likely most folks don't charge to 100% while using a generator--the run times are just too extravagant. In any event batteries are going to cost whether you do solar or generator. So they are an ancillary expense.

valhalla360 wrote:

Tbone wrote:
Solar PV cost, 260w = $570
Charge controller= $200

Total PV cost for 20yrs= $770/20= $38.50/yr
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You indicated your system will run the A/C for 4.5 hours. Two questions related to this:
1) Your profile indicates Arizona. Do you do any boondocking in hot conditions? If it's worth bothering with the A/C, we usually want more than 4.5 hours worth. Of course we have spent a lot of time on the east coast where it is humid and the temp doesn't drop as dramatically at night so the A/C often runs all night long.
2) Is this a standard roof mounted unit? Ours draws and 10 amps continous (tested with amp meter). My rough estimate is this would pull around 450 amp-hours out of a 12 volt battery bank. Previous posts implied you got around 100-150 amp hours per day. Does this mean you can only run the A/C for 4.5 hour every 3-5 days?

How big of an inverter do you have? I have a small 300 watt unit that was under $100. In looking at web sites, I'm seeing 2000 watt inverters with enough surge capacity to start an A/C are up around $2,000. This is a major cost factor to consider if you unit is not already equiped with such a large inverter.

If the A/C is non-standard, please provide the BTU output, amp draw (startup and continous) and cost so we can factor that into price comparison.

Quote:

it is a modified sine wave inverter but is rated to run microwaves and motors.

Wayne Dohnal wrote:

That's an interesting technical concept from the marketing department. I doubt that the microwave or motor knows if its MSW source is rated or not.

Wayne Dohnal wrote:

Pianotuna, I'm not trying at all to challenge what you've said. The deception of MSW is just one of my hot buttons. Even its name is a lie, as it's actually a modified square wave. The manufacturers have different ways of trying to put lipstick on the pig: Vector Maxx says "filtered MSW", TrippLite uses "PWM sine wave". I take the stand that Cobra's statement "This unit is ideal for microwave ovens" is a flat-out lie, as microwaves run at reduced cooking power when using MSW. The pulse width-to-height ratio varies among the manufacturers and some will run a microwave better than others, but they will all result in reduced cooking power as compared to a sine wave. I'm not even trying to demonize MSW inverters, just the dishonesty of trying to hide the fact that the power output is vastly different from a sine wave and sometimes it matters a lot. I'll jump off my soapbox now and apologize for an inverter rant in a generator thread.