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diy solar

What do I need to power these AC items

Dmbanke

New Member
Joined
Dec 31, 2020
Messages
5
Location
Ottawa, ON Canada
I am looking to run the following on my boat via solar panels, lithium batteries and an inverter.
1. 300W bar fridge
2. 900W fridge/freezer
3. 1300W individual coffee maker - run approx 8 times over 2-3 hours each morning

My thoughts were a 3000W inverter/charger so I could take advantage of shore power when I have it.
This would need 2 or 3 100ah batteries or better
A 30A MPPT
At least 400W of solar panels

Thoughts and comments welcome!

Daryl
M/V Destination Un Scheduled
Carver 360 Mariner
 
You need to come up with an actual total of watt hours. The 300W bar fridge probably doesn't use the full 300W every moment of the day. Come up with an actual total for each item in a 24 hour period so you know your total watt hours per day.

It may help to use the following energy audit:


Once you get your numbers in there it will show you estimated values for inverter, battery, and solar.

BTW - you don't need a 3kW inverter to take advantage of shore power.
 
12 volts suggests dc.
Inverters create ac from dc.
I suspect your question is malformed or misconcieved.
 
You need to come up with an actual total of watt hours. The 300W bar fridge probably doesn't use the full 300W every moment of the day. Come up with an actual total for each item in a 24 hour period so you know your total watt hours per day.

It may help to use the following energy audit:


Once you get your numbers in there it will show you estimated values for inverter, battery, and solar.

BTW - you don't need a 3kW inverter to take advantage of shore power.
The inverter/charger would use a shore power connection to run the items and charge the batteries when available.

Thanks! I will do the audit and maybe find a Kill a Watt meter.
 
The math for a a 3000 watt inverter charger at 12 volts looks like this.

3000 ac watts / .85 conversion factor / 12 volts low cutoff = 294.117647059 service amps
294.117647059 service amps / .8 fault headroom = 367.647058824 fault amps
That means 4/0 awg pure copper wire with insulation rated for 105C for the battery and inverter circuits.
That also means a 400 amp fuse for the battery and a 350 amp fuse for the inverter.
 
The key information is the locked rotor amps to start the compressors in items 1 and 2.
It could be up to 5 times the continuous draw.
 
Last edited:
The inverter/charger would use a shore power connection to run the items and charge the batteries when available.
Yes, that is true. I should have been more clear. What I meant is that it doesn't necessarily have to be 3kW. It can be whatever size it turns out you need.
 
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