Solar Upgrade verse Running the Generator

[Kenomac]

What did you think of my idea?

[Sailmonkey]

Originally Posted by Kenomac

Windpower is not worth the money or noise, especially when the OP already has a generator which can cram in more amps in one hour than wind can do in two windy days. My suggestion is to double solar and limit shading in order to take full advantage.

Agreed, I've got one.....in the grand scheme of things it contributes very little to the overall charge of the batteries. If I had more useable real estate for solar I'd add more!!

[john61ct]

Seems clear consensus to me, yes add solar.

But not either/or, you've also got the genset and will continue to use it occasionally as needed, ideally in the morning, big-amp mains charger to help ensure house bank gets back to 100% each day, greatly extend its lifespan.

Next bank, shop for a very high CAR chemistry to reduce runtimes even more.

[Exile]

Originally Posted by john61ct

If you were able to fit a genset's weight in panels and get rid of the genset. . .

Hate to be the only naysayer thus far, and it would no doubt be very nice for a lot of reasons (already discussed) to be more self-contained. Except for economic reasons that is. Especially if your boat already has a genset. If so, then nothing comes close to the energy/cost packed into a gal. of diesel, even when factoring in the add'l. costs (and hassle) of maintaining another engine. My 8kw genset is noisy down below, but almost inaudible in the cockpit (silent for other boats in an anchorage), and I can quickly charge batts. & also run every appliance on the boat while burning 0.5 gal/hour or less.

I think if/when I manage to leave the dock for good I'd take a look at a Watt & Sea instead, and maybe one 100-watt solar panel to keep up with battery self-discharge for when I'm at anchor and away from the boat. Decent quality solar panels & controllers are expensive, esp. if you also have to install arches, etc. to mount them (easier on cats). And I am doubtful that the added cost of potentially shortened battery life (from not topping up as much) improves the equation.

For Sailorboy, he already has a healthy amount of solar and has already made the investment in the genset. So adding more solar at this point would be more about reducing the inconvenience & hassle of running the genset (as Kenomac has done), and not saving boat bucks. There are good reasons for doing so, but the cost of doubling solar capacity would buy him a LOT of diesel & genset run-time.

[hafa]

In terms of upgrade, if you choose to add an additional panel, make sure that the VOC of the new panel is within 10% of the VOC of your existing panel. Whether you add an additional panel or choose to replace the existing panel with 2 new ones, ensure that your charge controller is adequate to accommodate the output, both in terms of voltage and amperage.

Regardless of which route you choose, I think you'll not regret upgrading.

[john61ct]

I specifically addressing the weight comment.

Best for shading is a controller per panel, the Victron 75/15 at under $100 is perfect for a high-volts unit rated under 250W.

[svseawitch]

4 panels on my arch. I run the generator to make hot water. Don't use the generator very much but glad I still have it for making hot water and when there is no sun...

[hafa]

Originally Posted by svseawitch

4 panels on my arch. I run the generator to make hot water. Don't use the generator very much but glad I still have it for making hot water and when there is no sun...

Apologies in advance to sailorboy1 for taking this off-topic.

Is it no longer common practice to circulate engine coolant through a heat exchanger to heat water? Our vintage unit works brilliantly, heating a large volume of water in a few moments.

[Kenomac]

Originally Posted by hafa

Apologies in advance to sailorboy1 for taking this off-topic.

Is it no longer common practice to circulate engine coolant through a heat exchanger to heat water? Our vintage unit works brilliantly, heating a large volume of water in a few moments.

The water heater works both ways. Engine coolant circulates through the water heater coils when it runs, and electric coils do it when at anchor. So the generator is needed. An idling engine won't heat up the water much, the generator is more efficient.

[Group9]

We just bought a boat that is equipped with an 8 kw diesel generator. And, still, one of the first things we did was add on 540 watts of solar panels.

[john61ct]

Yes, no dino juice source will get the bank to 100% full unless you're literally motoring all day long.

[Exile]

Originally Posted by Kenomac

The water heater works both ways. Engine coolant circulates through the water heater coils when it runs, and electric coils do it when at anchor. So the generator is needed. An idling engine won't heat up the water much, the generator is more efficient.

I'm assuming, even with your new solar array, that the electric h/w is too much of a draw for your batts. and/or inverter. If yours is like mine, the h/w heater draws about 10 amps off of 110v, and the start-up draw is at least 2.5x that.

[Exile]

Originally Posted by Group9

We just bought a boat that is equipped with an 8 kw diesel generator. And, still, one of the first things we did was add on 540 watts of solar panels.

Catamaran?

Other than as a backup for battery charging (when not running the main engine), which appliances still require the generator (assuming it's an AC not DC genset)? Usually it's aircon, h/w heaters, and 110v refrig. that will not work running off batteries/inverters.

[Exile]

Originally Posted by john61ct

Yes, no dino juice source will get the bank to 100% full unless you're literally motoring all day long.

Genset plus a good battery charger?? That's what I use anytime I'm away from the dock and under sail or at anchor. But yes, that last 15% will take awhile, but ditto with solar panels, esp. if you're also drawing loads during the 6-8 hrs. that the panels are supplying power. A propulsion engine will also do it in a matter of hours depending on the size of the alternator, type of regulation, size of battery bank, etc.

[john61ct]

A large bank depleted 40-50% can easily take over 8 hours to get truly Full.

A high-amps charger only saves an hour or so of that, and then only with a high CAR chemistry.

Yes some boats motor that long every day, but running a genny just for charging the last 4-5 hours "long tail" when a few panels put out enough current for that would be pretty foolish.