This is always an interesting question, but is always answered with a question.         

What do you want to run?

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Take an example:

A Houseboat will usually have the following requirements.

General interior lighting, some shore lights,water pumps, a TV, maybe a Sat Dish and a Fridge.

 

In most cases, you want to run all this without your generator going?   If so, then this is what you need to think about.....

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Requirement 1 : Batteries

Batteries must be able to run all of this for 16 non daylight hours.

The most common battery now used is the AGM (Absorbed Glass Matt) Battery. .

• Fridge on a 50% duty cycle will consume 32a/h of power overnight.

• A TV used for 5 hours will consume 40a/h of power .

• General LED lights for 5 hours will consume 40a/h of power

• Water pumps general use may consume another 5 a/h   =  Total 117 a/h 

 

A "new" AGM Battery is considered flat when 50% of its power has been consumed so you will need in excess of 234 A/H of battery power available

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My recommendation  is 440a/h minimum in battery capacity.  2 x 220a/h AGM batteries

Note: When connecting batteries together, all batteries must be of the same type and age.

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Requirement 2: Solar Panels

Panels must be able to provide power for all that is lost overnight, plus the power requirement for the day all in 8 hours of daylight if your lucky..

Whilst General light use will go down during the day, fridge consumption will go up as the heat of the day comes on..

Based on 117 a/h used in the 16 hours overnight, you will have another 60a/h consumed in daylight hours.

Your panels will need to produce 310w of Power. 

Note: Summer, Winter ,Sunny or Cloudy , Solar Panel capability can vary greatly so an acceptable compromise would be to base calculations on a panel efficiency of around 40% on average.

This means you would need around 770w of panels at a minimum. My recommendation in this case is 880 - 1000w for this installation.  

Note: All Panels must be of the same type and age

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Requirement 3: Solar Regulator

This must be a 3 stage MPPT regulator. No compromise.

In this case you would need a minimum of a 50A MPPT Solar Regulator  

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Please note:

This is an indication only,  everyone's power requirements will vary.. but easily calculated. 

** Guess work will most likely end in costly disappointment. **

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Hope this helped a little.

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