How to measure how much solar we need?

pianotuna wrote:

Solar Spread Sheet N8GS

Yes.

Estimating often works better than measuring because measuring needs to be averaged. On estimates you can throw, say, 20% up-margin, and if you're reasonable, it will work.

Some things need to be measured though. Like DC draw of your LP fridge.

If you don't know much about solar and need to ask "how to measure", you probably don't have much general electrical knowledge either. Then you will need - very likely - services of solar installer. They are to be kept a close eye on, the industry is not regulated and many are simply hillbillies with multimeter and pair of pliers, minimal skills and no professional ethics. The best you can do is to figure out the approximate values for total solar wattage, battery bank, inverter, recommended brands and models for those (not for panels - here brand and type are not important) - and put these requirements before the installer.

One good advice was there - if you want to stop making guys in turbans rich, max it up. There is no such thing as too much solar. If 1000W array fits, then put it. Solar guidelines of 60-100W per 1 AH of battery bank are just guidelines. You can't have too much solar. You can always set a limit on solar charger to prevent the current from spiking too high on a bright day. OTH, on a dark day a 1000W array will work as 100W, supplying just enough to get by. Consequently, a 100W array on a dark rainy day will work as a 10W, supplying almost nothing.

Battery bank size is a slightly different matter, they are heavy, need to be taken care of and need to be replaced from time to time. You can't carry more battery bank than you can, anyway. If the goal is living generator-free, then for long-term living your battery bank should be big enough to prevent the charge from dropping below 50%. So with battery bank you also should try and go big, - within a reason.

path1 wrote:
Wife on "power diet". Yep, been discussed many times. "why bother having an RV if we aren't going to use what the heck is in it?" She's got a point...

This is a flawed logic. Like saying "why bother going shopping if you can't afford spending a few grand in one day" (or 10K, or 50K, whatever number describes your situation best).

For some people solar Rv-ing is simply impossible, as you've probably realized. Not because they always camp where it's dark and rainy, but because they want RV to be what it is not - carrying items that don't belong in RV, in terms of size and energy use. This isn't a shore home, you can't have 9000W solar farm there. RV manufacturers aren't helping much, either. They make RVs unbelievably energy-inefficient, with prehistorical lighting, heating and ventilation.