Opinions on solar power

[EmeraldCoastSailor]

You have about the same energy budget as my boat. A while ago I upgraded house batts to 4 6v golf cart batts = 450 AH. I realize 200 watts isn't going to get it done perfectly but right now I charge the batts via engine as I go from point A to point b, never staying away from shore power for more than a week so I frequently get fully charged in a slip. As I slow down and spend more time in one place not in a slip I was thinking two 100 watt flex panels might give me a good entry into solar and cut meaningful engine run times but not all. And I use a Yeti with dry ice which lasts quite some time so Fridg dependence goes down. My week long adventures are not full cruising so I was going to plan for 4 flex panels on Bimini and start with 2 as I further understand my usage trends.

[buzzstar]

You have received lots of good advice, with corrections and explanations too. If you are not going to use refrigeration right away, I suggest start with your 240 using hard panels, but layout and set up for at least one more panel, perhaps two, so you can increase capacity if and when needed. You may also want to consider such things as wind or even, as mentioned, a small generator. AND do not forget the batteries, their storage capacity is vital. While I am sure you know, and the previous posters do too, although I did not see it in my quick scan of the thread, rarely, if ever, do alternate energy sources live up to their advertised output specs.

[Caliber40]

Originally Posted by ErikFinn

and I thought I made a special effort to make it exceptionally clear..

I understood you!

[ErikFinn]

Originally Posted by Caliber40

I understood you!

Thank You!

[buzzstar]

Originally Posted by ErikFinn

and I thought I made a special effort to make it exceptionally clear..

You clearly did. In fact so you did it so well that it deserved repetition. But not so well that it did not need repetition in different words.

[Kinta Ray]

Regarding the lifespan of the flexible panels, I have been told that a regular clean and application of polish will extend the life to close that of a hard panel. If they become clouded they can be restored with a mild cut and polish, just don't get too carried away or leave them unpolished as this speeds up the clouding. Hope this helps.

[Paul L]

Originally Posted by Kinta Ray

Regarding the lifespan of the flexible panels, I have been told that a regular clean and application of polish will extend the life to close that of a hard panel. If they become clouded they can be restored with a mild cut and polish, just don't get too carried away or leave them unpolished as this speeds up the clouding. Hope this helps.

Besides being yet another maintenance item, it sounds more like marketing hype than reality, at least in the tropics. Also flex panels have a shorter life because they flex. Lots of good reasons to use flex panels, but longevity as compared to ridgid panels isn't one of them.

[Pizzazz]

This is a recurrent topic and the typical suggestion is add more batteries and solar. I disagree. The battery capacity is not that important as long as it can last you through the night with some reserve. So, how do you generate electricity on board:

1) Run the engine. On a typical 30-35 boat, you will generate 80 A/H and use 1/5 gph in fast idle. By far the cheapest and simplest method. You may need to upgrade the alternator but that is inexpensive.

2) Next, you can install solar. Every 100 watts of panel will give you 25 AHr per day or the equivalent of 20 min engine run-time. You have to avoid shading, use mppt controllers and maximize the angle to the sun. I believe some solar is essential as a backup (radio, charging starting battery if dead, etc.) But the majority of you AHrs will come from the engine.

3) If you find you are running the engine a lot (more than 300 hours a year), you may consider a generator.

Lastly, do heed the advice to look at the whole system. For example, running the engine is efficient only in bulk charging mode, which means an appropriate battery capacity and state-of-charge and so on.

Happy reading

S/V Pizzazz

[StuM]

Originally Posted by Pizzazz

This is a recurrent topic and the typical suggestion is add more batteries and solar. I disagree. The battery capacity is not that important as long as it can last you through the night with some reserve. So, how do you generate electricity on board:

1) Run the engine. On a typical 30-35 boat, you will generate 80 A/H and use 1/5 gph in fast idle. By far the cheapest and simplest method. You may need to upgrade the alternator but that is inexpensive.

2) Next, you can install solar. Every 100 watts of panel will give you 25 AHr per day or the equivalent of 20 min engine run-time. You have to avoid shading, use mppt controllers and maximize the angle to the sun. I believe some solar is essential as a backup (radio, charging starting battery if dead, etc.) But the majority of you AHrs will come from the engine.

3) If you find you are running the engine a lot (more than 300 hours a year), you may consider a generator.

Lastly, do heed the advice to look at the whole system. For example, running the engine is efficient only in bulk charging mode, which means an appropriate battery capacity and state-of-charge and so on.

Happy reading

S/V Pizzazz

Be wary of heeding the advice of people who think that A/H is a measure of alternator output.

Alternators/generators are great for the initial bulk charging of a LA battery when it is at a low state of charge, it is a very wasteful way of trying to put the last 10-15% of charge back into the battery because it will take hours of engine time. This is where solar comes into its own.

[Pizzazz]

Originally Posted by StuM

Be wary of heeding the advice of people who think that A/H is a measure of alternator output. [emoji2]
Alternators/generators are great for the initial bulk charging of a LA battery when it is at a low state of charge, it is a very wasteful way of trying to put the last 10-15% of charge back into the battery because it will take hours of engine time. This is where solar comes into its own.

Stu,
80 A/H means 80 amps per hour which when coupled with the 0.2 gph, gives the OP enough information to figure out you can produce 5x80=400AHr per gallon. So, it is quite alright if non-standard.

I do not really see your motivation for commenting on every CF post, nitpicking, without adding new ideas.

[chris95040]

Originally Posted by Pizzazz

Stu,
80 A/H means 80 amps per hour which when coupled with the 0.2 gph, gives the OP enough information to figure out you can produce 80A*5hr=400AHr per gallon. So, it is quite alright if non-standard.

I do not really see your motivation for commenting on every CF post, nitpicking, without adding new ideas.

Please read posts 26 and 27. It's not that your units are non-standard, it's that they are incorrect! You are being helpful, and Stu is trying to help you be even more helpful.

I see that you mean to say is Amp hour per hour. That's easier expressed as just Amp (see correction above).

Or , if you prefer, the amp hour donkey giraffe per hour donkey giraffe.

[StuM]

Originally Posted by Pizzazz

Stu,
80 A/H means 80 amps per hour which when coupled with the 0.2 gph, gives the OP enough information to figure out you can produce 5x80=400AHr per gallon. So, it is quite alright if non-standard.

I do not really see your motivation for commenting on every CF post, nitpicking, without adding new ideas.

No such thing as Amps per hour.

[conachair]

Originally Posted by Pizzazz

1) Run the engine. On a typical 30-35 boat, you will generate 80 A/H and use 1/5 gph in fast idle. By far the cheapest and simplest method. You may need to upgrade the alternator but that is inexpensive.

Unless you want to get the batteries fully charged which would mean running the engines for hours, no matter what size of alternator you fit. That last 20% or so will still take something like 4 hours.

[Copacabana]

I would suggest first trying to reduce your consumption on board by using only LED lights and cutting power use where possible. Since you don't mention anything about your fridge, it's hard to know what its power draw is. 240w of solar might be enough to keep up with your power needs, but all the laptop, Ipad, phone etc. charging may be too much to keep up with. FWIW, I have only 90w of solar at present and a 210a battery bank and will soon install a monster 270w (60 cell/30v) panel over my bimini to bring my total solar up to 360w. I'm pretty sure it will be overkill for my power needs. I have an Engel fridge (very low power consumption), all LED lighting, no electric pumps (except bilge) and a normal amount of electronics. I figure I use less than 50ah a day at anchor. I'm hoping my solar array will generate about twice my energy needs on most days. It's always cheaper in the long run to reduce energy consumption than it is to generate more energy (especially if you have to buy a generator!).

[StuM]

Originally Posted by conachair

Unless you want to get the batteries fully charged which would mean running the engines for hours, no matter what size of alternator you fit. That last 20% or so will still take something like 4 hours.

Apparently pointing out bad advice like that is just nitpicking without adding new ideas.