Just finished going through purchased boat and discovered the survey showing two batteries was incorrect. This boat has never been wired for two batteries and the current charger is broken. Can I install a solar panel and get sufficient productivity out of one battery? If so, what spec. for a panel should I look for?
Solar Power?
- Thread starter FourPlay
- Start date
- Status
Yes but it depends
To design a solar power system you need to know the amp-hours (AH) produced by the solar cells, the AH capacity of the batteries and the AH usage for a typical usage cycle. From a dollars standpoint it will be cheaper to buy a new charger and rewire the batteries. You would need to do that anyway so you can recharge while at the dock and have a second bank to start the motor with if you run down the house bank. If you have a boat with only a few electrical loads (bilge pump and nav/anchor lights) then solar MAY be the way to go. You will have to balance your AH production-storage-usage values as a system in any case. What kinds of loads does your boat have and how often do you use them? What is the AH capacity of your batteries?
To design a solar power system you need to know the amp-hours (AH) produced by the solar cells, the AH capacity of the batteries and the AH usage for a typical usage cycle. From a dollars standpoint it will be cheaper to buy a new charger and rewire the batteries. You would need to do that anyway so you can recharge while at the dock and have a second bank to start the motor with if you run down the house bank. If you have a boat with only a few electrical loads (bilge pump and nav/anchor lights) then solar MAY be the way to go. You will have to balance your AH production-storage-usage values as a system in any case. What kinds of loads does your boat have and how often do you use them? What is the AH capacity of your batteries?
solar calculator
As previous reply indicates, it might be more economical to add the 2nd battery and switch. I am adding a solar system to my h-30 from www.wholesalesolar.com but here is a link to where you can design your system and figure your wattages needed.
As previous reply indicates, it might be more economical to add the 2nd battery and switch. I am adding a solar system to my h-30 from www.wholesalesolar.com but here is a link to where you can design your system and figure your wattages needed.
Interesting site Chuck
Clearly aimed at the solar power for the home crowd. I'd caution anyone using it to not forget that your batteries provide all your power and the solar panel just keeps the batteries charged. So if you do weekend day sailing you have all week to recharge the batteries but if you are a live aboard you only have 1 day. This site does not take this into consideration. You really have to know how your are going to be using the electrical power (amounts and times) and what your storage capacity (AH) is before you can pick a solar panel that will meet your needs. A silly example: Lets say all I have is 1 bilge pump and an anchor light. bilge pump draws 6 amps when it runs and it runs for 5 seconds every hour 24/7 anchor light draws 3 amps and only runs when I'm at anchor. Lets also assume your batteries can in fact supply the AH needed to get you through each cycle. Case 1 weekend anchor out Friday and Saturday night otherwise the boat is in its slip. Case 2 cruising and anchoring out every night. case 1 has to be analyzed over a whole week as that is the shortest time for one complete cycle of usage while case 2 only needs to be analyzed over one day. The bilge pump draws 6 amps * (5 sec/60 sec per min/60 min per hour) hours = 0.00833 AH each time it is used. Since it gets used 24 times each day that means 0.2 AH/day. This is the same for both cases. The anchor light draws 3 amps * 10 hours = 30 AH each time it is used. For case 1 that would be 2 times or 60 AH and for case 2 that would be once or 30 AH The total usage for case 1 would be (0.2 * 7) + (30 * 2) = 61.4 AH per cycle The total usage for case 2 would be (0.2 * 1) + (30 * 1) = 30.2 AH per cycle Now case 1 has 7 days for the solar panel to recharge the battery while case 2 only has 1 day so we get case 1: 61.4 AH/7 days = 8.77 AH per day that the solar panel needs to provide to keep the batteries topped off at the beginning of the weekend anchoring out. You will come home on Sunday with a partially discharged battery. case 2: 30.2 AH/1 day = 30.2 AH per day that the solar panel needs to provide to keep the batteries topped off. A 8.77 AH per day production means 8.77 amps / 10 hours of sun per day = 0.877 amps each hour the sun is shining. So a 1 amp solar panel will work. (this is a GROSS oversimplification as weather and battery storage losses..... are not factored in) A 30.2 AH per day production means 30.5 amps / 10 hours of sun per day = 3.5 amps each hour the sun is shining. So choose a 4 amp panel A 1 amp panel would be 1 amp * 13.7 volts charge voltage = 13.7 watt panel a 4 amp panel would be 4 times that or 54.8 watts Two identical systems used two different ways. It makes a difference. In this case about $500
Clearly aimed at the solar power for the home crowd. I'd caution anyone using it to not forget that your batteries provide all your power and the solar panel just keeps the batteries charged. So if you do weekend day sailing you have all week to recharge the batteries but if you are a live aboard you only have 1 day. This site does not take this into consideration. You really have to know how your are going to be using the electrical power (amounts and times) and what your storage capacity (AH) is before you can pick a solar panel that will meet your needs. A silly example: Lets say all I have is 1 bilge pump and an anchor light. bilge pump draws 6 amps when it runs and it runs for 5 seconds every hour 24/7 anchor light draws 3 amps and only runs when I'm at anchor. Lets also assume your batteries can in fact supply the AH needed to get you through each cycle. Case 1 weekend anchor out Friday and Saturday night otherwise the boat is in its slip. Case 2 cruising and anchoring out every night. case 1 has to be analyzed over a whole week as that is the shortest time for one complete cycle of usage while case 2 only needs to be analyzed over one day. The bilge pump draws 6 amps * (5 sec/60 sec per min/60 min per hour) hours = 0.00833 AH each time it is used. Since it gets used 24 times each day that means 0.2 AH/day. This is the same for both cases. The anchor light draws 3 amps * 10 hours = 30 AH each time it is used. For case 1 that would be 2 times or 60 AH and for case 2 that would be once or 30 AH The total usage for case 1 would be (0.2 * 7) + (30 * 2) = 61.4 AH per cycle The total usage for case 2 would be (0.2 * 1) + (30 * 1) = 30.2 AH per cycle Now case 1 has 7 days for the solar panel to recharge the battery while case 2 only has 1 day so we get case 1: 61.4 AH/7 days = 8.77 AH per day that the solar panel needs to provide to keep the batteries topped off at the beginning of the weekend anchoring out. You will come home on Sunday with a partially discharged battery. case 2: 30.2 AH/1 day = 30.2 AH per day that the solar panel needs to provide to keep the batteries topped off. A 8.77 AH per day production means 8.77 amps / 10 hours of sun per day = 0.877 amps each hour the sun is shining. So a 1 amp solar panel will work. (this is a GROSS oversimplification as weather and battery storage losses..... are not factored in) A 30.2 AH per day production means 30.5 amps / 10 hours of sun per day = 3.5 amps each hour the sun is shining. So choose a 4 amp panel A 1 amp panel would be 1 amp * 13.7 volts charge voltage = 13.7 watt panel a 4 amp panel would be 4 times that or 54.8 watts Two identical systems used two different ways. It makes a difference. In this case about $500
use solar for float charging or very light usage.
Solar panels do not put out alot of power- period. Bill Roosa went through alot of calculations - great job Bill. Cleary, you can see that if you want solar you need either alot of solar panels or alot of charge time. If you consider solar - go through your usage and go through the calculations. You have to be smart about this because if you need your engine started and there isn't enough charge, you might like the consequences.
Solar panels do not put out alot of power- period. Bill Roosa went through alot of calculations - great job Bill. Cleary, you can see that if you want solar you need either alot of solar panels or alot of charge time. If you consider solar - go through your usage and go through the calculations. You have to be smart about this because if you need your engine started and there isn't enough charge, you might like the consequences.
The lazy mans way
I have a excel spreadsheet I made for myself that does all the calculations for AH and such. All you need to know is how you use your loads and then you can play with the battery bank capacity and production means. send me an email at roosaw@verizon.net if you want a copy.
I have a excel spreadsheet I made for myself that does all the calculations for AH and such. All you need to know is how you use your loads and then you can play with the battery bank capacity and production means. send me an email at roosaw@verizon.net if you want a copy.
You can get a lot more time out of a battery if
you convert to LED light bulbs. If you have refrigeration, AC, or other high draw equipment, you will need to top up with shore power or engine charging. We use an ice chest and a solar (garden style) anchor light, so lights for reading is about all we draw. This means one 5 watt solar panel will keep the batteries up. There are islands near us where folks live full time on solar. They spend around $10,000 on panels, which is enough for lights, TV, music, and a small refrigerator. Most of these folks have a diesel generator for the washer, dryer, table saw, and maybe twice a week for the freezer. It's a pretty good system. less than 5 gallons a month for the gen set, and the rest is free.
you convert to LED light bulbs. If you have refrigeration, AC, or other high draw equipment, you will need to top up with shore power or engine charging. We use an ice chest and a solar (garden style) anchor light, so lights for reading is about all we draw. This means one 5 watt solar panel will keep the batteries up. There are islands near us where folks live full time on solar. They spend around $10,000 on panels, which is enough for lights, TV, music, and a small refrigerator. Most of these folks have a diesel generator for the washer, dryer, table saw, and maybe twice a week for the freezer. It's a pretty good system. less than 5 gallons a month for the gen set, and the rest is free.
- Status