The real cost of solar power?

[coot]

Originally Posted by colemj

So what am I missing? It seems that solar actually equals shore power in cost and beats the other options. Although in practice, you would get by with a cheaper, lower output charger using shore power because it would be on all of the time. But again, it would be useless away from the dock.

I think your $3000 estimate for shore power is way high. As you mentioned, you could use a smaller charger. You could also forgo the inverter (which has nothing to do with charging your batteries) and get the price well under $1000.

Most boats are going to have a main engine anyway, so you can't count the cost of the engine as the cost of charging your batteries. You would have spent that money anyway. I use the stock alternator on my engine, so the additional cost of charging my house batteries is about $200 (battery isolator, cables, switches) plus operating costs.

Some people prefer to buy a bigger alternator, which brings the hardware cost up around $1000 for an alternator plus charge controller.

So, for example, ordinary shore power and main engine with standard alternator together cost about a third of the cost you give for solar. Even with the bigger alternator, it's around two thirds.

Also, solar power doesn't work so well in rain/snow, so you probably want to have a backup. Suppose I have shore power for $1000 + main engine charging for $200. Doesn't the solar (which I don't even need any more, because the other two can cover the power requirements) for $3000 look less attractive?

[schoonerdog]

The cost of your engine is actually around $15k, and it's only good for running a certain number of hours before having to be rebuilt or replaced. It also wasn't made to idle with a high output alternator attached. I'm not a diesel mechanic, but I've heard the same thing from mechanics for Yanmars, running your engine to charge your batteries isn't good for the engine. Some engines I've heard void warrantees if over a certain sized alternator is placed on them. So no, 3k for a solar panel looks pretty cheap compared to prematurely glazing a diesel engine and having to replace a 15k engine. Not to mention running it in a harbor tends to be the dirtiest water possible and really increases the risks of sucking something bad in and clogging your intake. This isn't marine diesel link, but it shows the general concepts....

Diesel engine idling, from an authority: Detroit Diesel « BusBuilding.com

[Boracay]

Can anyone comment on the cost of fixing (in terms of frequency, man hours, parts and general inconvenience) of main engine, generators, solar, wind and water electricity generators.

I know that engines are a total pain in the @## to fix.

[hellosailor]

Mark (cole)-
I don't think you can run the numbers that easily. A Coleman 7KW genset is only $1000. How you figure a 7kW genset is $10,000 I don't know but obviously, there's a wide range to be covered.
And even with the MPPT controller, getting 200AH a day, reliably and at full power, from a 4x130W rated array may seem problematic when typical numbers are used and SolarStiks are not invoked.<G>

Then there's shore power. That can range from 6c to 25c per KWH ignoring marina surcharges. 200AH at 14v is about 2.8KWh, which would be from 16.8c to 70 cents per day, or $62 to $255 per year from shore power.

A "reasonable" price for power is like a "reasonable" price for foul wx gear. All depends on how badly you need it.<G>

[colemj]

Thanks for the replies. One thing I would like to make clear in this discussion is that I was intentionally simplifying a lot of assumptions in my rough calculations. For example, I assumed for the solar panels that I would get full output for 7hrs/day, but I also assumed that an engine driven alternator would provide full output for the time it was operational. I really think that the various and different losses between the systems do actually equal out and that my simplified assumptions are proportional to real world operation. I base this on my observations from having a large solar panel bank, a generator, two engines with alternators and shore power connected to a large charger from which to chose when charging (actually, I don't "get" to choose - they choose for me, but that's another thread on wiring circuits).

Also, I agree that some of my estimates could be off - I am not working off of actual costs, but am taking some guesses as to what some things cost. I know I am in the ballpark on charger, solar panel and controller costs.

To answer specific concerns about my assumptions:
- I assumed a 6kW marine diesel genset feeding an inverter/charger capable of 100+ amps with install to be ~$10,000. I agree there is a wide range to cover, but I wasn't considering non-marine, gasoline air-cooled gensets (I was putting these in the catagory of alternate systems that I didn't have experience with - thus the original question of "what am I missing?"). This is one of the areas where I admit I might be off by a couple of thousand $$, but I KNOW I am not off an order of magnitude. But let's suppose the generator does only cost $1,000. The charger/controller would cost another $1,000. I promise you that the remaining $1,000 difference would not cover the costs of operation for the next 25 years (the warranty period of solar panels).

- My assumptions on shore power included installation of the shore power system with breaker panel, etc along with a high output charger and charge controller. I based this partially on a quick google search for 90A Iota charger and controller which looked like it would be well north of $1,000 not regarding the shore power system. I will grant that many boats already have the shore power sytem installed. However, shore power doesn't really come into play in this discussion. If you are always connected to shore power, you probably wouldn't be reading a thread on relative costs of solar power. For all systems I ignored the consumable costs of electricity and diesel. I guess I could also ignore the cost of decrease efficiency of the solar panels due to global warming (ducking).

- I agree that an engine is already installed on the boat, so it is a bit disingenuous to count that as "extra". However, I only meant to compare costs. And if we are to discuss using the engine as a charging source, then the conversation will get interesting. My thought experiment was to replace 200Ah. Using a stock alternator is a very poor means of replacing a lot of lost Ah. I don't even think it can be done within reason, and I base that on having two engines with stock 60A alternators. Even a high output alternator is not going to get you close to this without a lot of engine running time, and for those with modest engine sizes, a large alternator may not be feasible.

- Taking shore power and main engine together, I still don't think it is possible to replace 200Ah within the same amount of time as solar for less than the cost of the solar installation. Although this is changing quickly due to the skyrocketing cost of getting solar equipment.

- I refuse to think of having issues with solar panels due to snow, and demand you apologize to me for making me even consider it

- Now I lost my train of thought because I was reminded of snow.

So, I am willing to believe that solar is expensive, but so far the arguments are not convincing to me...

Mark

[colemj]

Originally Posted by Boracay

Can anyone comment on the cost of fixing (in terms of frequency, man hours, parts and general inconvenience) of main engine, generators, solar, wind and water electricity generators.

I know that engines are a total pain in the @## to fix.

I can speak to some of it:
- I have spent zero time maintaining my solar panels over the past 4 years. If they weren't providing shade over my head I wouldn't even know they were there.
- I change my main engine oil once/year (it is winterized half the year), and probably spend another 2-3 hours every season doing some other type of maintenance (impeller, jellyfish in strainer, rebuilding water pump, belt tightening, etc).
- I spend more time on the generator than the engine, and it is newer and run less often. These are high maintanence items no matter what marketing tells you.
- No experience with wind or water generators.

Mark

[Lynx]

I see that most of the cost of the generators does not include how much fuel it use to make the Amp/hrs per day or preplacement cost or maintance.. This does add up. The honda 1K will take about 1 gal per 8 to 12 hrs of use. Or about $ 1000 per year with everyday use.

There is really a lot to consider but what I have found that it really depends if you want to have a motor running or not to charge your batteries.

[ssullivan]

I can add to the discussion regarding gensets vs solar/wind:

We had priced out solar with wind, since solar is not entirely useful in the northeast by itself. The solar and the diesel genset were the *exact* same cost over a 5 year period. Solar/wind were a lot more money up front, but were less $$ over a 10 yr period (assuming the wind gen didn't break down, although we DID assume the genset would break down).

We were in the midst of a refit, and couldn't cough up the $8K for solar and wind (Mark, where are your numbers for the charge controllers, mounting hardware, having all specialty 12V items or an inverter?).

So, instead we chose to spend $3000 on a Yanmar powered diesel genset and put in two 90 Amp chargers for a total cost of about $3500 or $3800. There were no additional items to purchase, as I just plug my twin 30 amp shore power cables directly into the genset when not at the dock. They stay plugged into the genset.


While at a dock in the winter, I just take those same cables and plug them into the shore power. The chargers serve dual purpose of charging the batteries at anchor or at the dock without need of any charger controller or other fancy items.

The best part is that while we are able to do everything solar and wind can (keep batteries charged), we are also able to do things like use a toaster oven, air conditioner (although we never have), and high draw power tools for hours and hours on end without having to wait for solar/wind to top things off. (picture using a big 15 amp Makita angle grinder with lambswool pad to buff your boat at anchor with solar) I get a full 50amps (@120VAC) of power out of this genset to use as I wish at anchor.

So far, I have close to 200 hours on the genset, since I only need to run it for 40-45 mins each day now that we have no charter guests.

As much as I enjoy the genset, it would be nice to add a wind gen to the scenario and switch to 12v refrigeration. Some days, I run the genset ONLY for the refrigerator, and don't need the extra power for the batts. This is the disadvantage to my particular setup.

The last drawback we saw was that if you buy solar and wind, and are living aboard your boat and are NOT in the tropics with tradewinds and tons of sunshine - you STILL need to buy a genset to make power for cloudy, windless days. That's the real kicker.

[hellosailor]

Mark-
"I guess I could also ignore the cost of decrease efficiency of the solar panels due to global warming (ducking)."
No need to duck, Comrade! All dachas on the newly defrosted Kamchatka Peninsula will be served with free dockage and free shore power, grab one now before the great land rush!
Global warming looks bad to us now, but the ice age it has prevented--would have looked way worse.

[forsailbyowner]

Dont forget to factor slip rent into that cheap shore power. After you get away from that all the alternatives look good for power generation ,economically.