Solar/Inverter Question

Lwiddis wrote:
The minimum is one solar watt per battery amp hour. This is a very common issue leading to “my solar didn’t recharge my batteries...it doesn’t work!” You need at least 65 more watts. I’m 240 amps with 300 solar watts.

Rules of thumb can often be way off the mark. Also unless you go to extremes, it's just a question of time to recharge not if it recharges.

Do an energy audit.

Figure out what devices you are running and how long they are running. Each device will have a wattage rating listed on it.

Watts * Hours = Watt-Hours

Add them all up to get the total used.

6v * 235 amp-hr * 2 batteries = 2820 watt-hours in the battery bank but you can't use all of those for lead acid batteries, you don't want to drop below 50% or about 1400 w-hr if you start from full.

Solar panels don't put out their max rating except under perfect conditions. A good estimate is 4-5 times the rating in w-hr, so 170w panel will generate around 680 w-hr per day.

So if you are consuming 1200 w-hr per day, after the first day, you will be down to around 800w-hr available in the battery bank, after the 2nd day, you will be down to 200 w-hr.

Of course, you want to factor in some inefficiency as battery banks are not perfect at charging and as you mentioned, dirty panels don't put out as much...so in reality, after 2 days, you would have used all the power you can without risking damage to the batteries.

For a 2-3 day weekend trip with light use, your system should be OK but you really need to watch your usage.

If you are doing longer trips, I would lean toward more solar so you are mostly replacing what you used.
If you are just using more but only for 2-3 day trips, adding a couple more batteries may be simpler and then let them charge off the solar during the week when you aren't drawing any power.