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
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...