Opinions on solar power

[Stu Jackson]

Solar Sizing


Calculate daily A-hrs consumed, multiply that value by 4 for battery capacity in A-hrs and for solar array in Watts. This is the minimum. That simple.

e.g. If 100 A-hrs / day consumption, then 400 A-hrs of FLA battery capacity and 400W of solar.

From: Matching solar panels to batteries to consumption - Page 3 - Cruisers & Sailing Forums

[Kenr74]

Opinions are great for brands of equipment, suppliers, etc... Requirements for power systems should be far more science than opinion. Although I grumbled at spending the money, I recently bought Nigel Calder's book, Boat Owners Mechanical and Electrical Manual. It really covers the issues you need to know in planning an electrical system. I am confident this book gave me enough knowledge to more than pay for itself in saving me from mistakes I almost certainly would have made otherwise. I have no affiliation with the author, just a satisfied reader.

[newhaul]

On thing I never seem to see mentioned is to get the appropriate DC to DC converters to charge your portable toys. Saves many ah that would be lost using an inverter to plug the normal house chargers in that convert the inverters ac power back to DC to charge your toys.
(What did we ever do before we had all of these electric powered toys when we cruised)

[Celestialsailor]

Originally Posted by markwesti

Forgot , your batts. are also part of of the set up . keep them fresh and big and more than 2 . We are on the 6v deep cycle thing . We have the two 6vs' = 12 v and a starting batt .

Originally Posted by onebigadventure

I have been reading that people use these 6v deep cycle. What is the difference between that and 12v? I was also looking into golf cart batteries i hear work well.

Yes...batteries...

Here is how I have done it for years now. I currently have 300 watts of panels. I have 3, #31 deep cycle batteries equaling approximately 330 amp/hrs. One a boat before this one, I had 200 watts of solar and 2, #31's equalling 220 amp/hrs. This sizing technique seems to balance out well. Currently, with the loads I have, I need to run my engine/alternator every 2-3 days which at that time run a watermaker. It balances out well.
You need to start somewhere. Then see if it meets your needs or not.
It wouldn't work well if you had one, #27 deep cycle with 500 watts of solar, nor would five, 8D batteries with 50 watts of solar.

[onebigadventure]

Now to judge how many amp hours i will use a day. Is there a way to do that before I buy everything? Or charts to estimate what i will be using?

[onebigadventure]

I do not plan on using refrigeration right away but i do want to have the option.

[Kenomac]

240W is not enough, refrigeration will be your largest consumer of amps. Ask Sailorboy1 how he's doing with his solar setup.

[CaptRory]

The batteries are the heart of the system. The easiest electric upgrade is more capacity. I use four 6 volt AGM's for 480 amp hours, with a separate starter battery. I power them with two Kryocea 180 watt ridgid panels, mounted over the bimini, for a total of 360. With that I live the electrical life style you describe including pressure water. LED cabin and running lights. AGM's are expensive, but they don't require a vented box (they don't gas...one less thing) and you can install them on there side or what ever it takes to make them fit. When I was shopping, 4 years ago, rigid were more efficient and cheaper. That may have changed.

[markwesti]

Originally Posted by onebigadventure

I have been reading that people use these 6v deep cycle. What is the difference between that and 12v? I was also looking into golf cart batteries i hear work well.

Not to stop this thread but .... This guys site is a wealth of info in the past he has saved the day for me more than once .

Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com

[onebigadventure]

Thanks. The more reading i can do the better. I want to educate myself on it as much as possible before I buy. Thankfully i will have shore power fir a few months.

Originally Posted by markwesti

Not to stop this thread but .... This guys site is a wealth of info in the past he has saved the day for me more than once .

Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com

[DeepFrz]

Treat your electrical system as a system. Focusing on one aspect of the system is premature.

[Caliber40]

Placement of panels to avoid shadows or to capture low sun angles is very important. My flexible panels mounted on my Bimini are very inefficient. They lay flat so I capture no sun angle .

Hard panels mounted on the rails are Ok but I typically only capture sun on one panel.

I'd look to mounting rail mounted as well as tilting arch or Davit mounts.....480 W +\- if you have the room!

[barnakiel]

I think 240 Watts will not be enough to run an AP and a fridge at once.

Ericson Independence is small but heavy and you will need quite an AP. Also, people who need fridges tend to use quite some fridges, not the smallest and lightest (energetic'ally) units. Count AP maybe 50Ah/day and a small fridge at least another 50. Add whatever your VHF, AIS and GPS and instruments might consume.

Alas, your engine will have an alternator, so make sure you have a fine unit and above all a fine 3 stage / 4 stage alternator regulator. Start the engine early morning, let it do the heavy lifting. Then the solars should easily top up your amperjar.

I think with a good alt set up and 240 W in solar you are making a good start. Independence has huge cockpit, so will likely be able to add more solar capacity if you find you want more.

My wild guess is you want closer to 500 W solar.

I can tell you from our no AP no fridge perspective that 150W solar is just about enough to run all the other toys onboard (= LED lights, AIS/GPS/VHF, 2 tablets, toothbrushes, sex toys, etc.) We only use the sex toys on very sunny days though!

Have fun making it all work.

Cheers,
b.

[donradcliffe]

I'd plan on four 6v Golf Cart batteries hooked in series/parallel to give you 400 amp hours at 12v, plus 400+ watts in hard solar panels. That will be enough to power your systems 95% of the time. The hard panels will last 20 years, and the GC batteries should last 5-7 years.

[Sir Rondo Normal]

Originally Posted by onebigadventure

Now to judge how many amp hours i will use a day. Is there a way to do that before I buy everything? Or charts to estimate what i will be using?

Yes there is a calculation, you need to look at all equipment and find its rated current draw. Add them all up and estimate how many hours per day they will be drawing that resulting current and the answer is how many amp hours (ah) you will need on a daily basis.
(rated current + rated current, etc) * (combined est'd hrs of use) = ah required/day
To give you an idea via boat comparison, the equipment you said you'll be powering (although you didn't specify if your lights are LED) is similar to what we have on our boat.
This past summer (in BC, Canada) we lived aboard on the hook from April to the end of Aug. We have 440 ah battery bank, 180W of solar panels and 250W wind generator. We have LED nav/anchor/cabin lights, two macbook pros, an ipad, one iphone, VHF radio, Reefer w/freezer. Electric pressure water, propane solenoid, 2 macerator pumps (galley & head).

#1 The wind genny doesn't contribute much.
#2 We found we could go about 4 days without needing to start the engine to charge batteries as long as the sun was shining every day.
#3 We will be adding at least 200W more to our array this year.

Hope this helps. Good luck!