Solar help

[sternwake]

I've got 198 watts of flat mounted solar and 90Ah of battery and  my battery would be significantly happier with 300+ watts.

Any charging is better than no charging but a reliable system that yield excellent battery life, needs more than just whatever.

when designing a system, work withing the limiting factors.  400 watts can fit, then tailor the battery capcity to that, and regulate the loads to within their capabilities.

If the loads exceed their capabilities, then one can perhaps run engine while running the induction cooker so the alternator is powering most of it.

When Solar is to be the main or perhaps only charging source, you cannot have enough.

So Jim's answer of  " how much roof space is available? is the most succinct and accurate.

[justjim]

The first and foremost issue with the question of how much solar do I need will always be enough to produce more power than you use. only then does the ratio of watts to Amp hours comes into play.

The rule of thumb of 1 watt per one amp hour of battery capacity is a rule of thumb that I hear but it is the ratio required to equalize a battery at 77 degrees. Equalizing a fully charged battery does not take that much power.

Now then, what it takes to CHARGE a battery is a different thing all together. Have you ever seen a deeply discharged battery charge to 13.1 volts and hang there even though you have full sun on a 1-1 solar to Ah system? It happens because batteries have resistance to having power flow into or out of them. It isn't like turning on a tap and letting a bucket fill with water. You have to force the charge into them. You have to have enough watts to slap the battery upside the head and say wake the hell up. A 1-1 ratio simply isn't enough to do that. Eventually you will get there but it is going to take longer than you think.

As sterwake mentioned, time of year and location also plays into this. A 1-1 ratio in the dead of winter is actually 0.5 to 1 due to the angle of the sun reducing your peak power to half of what you see in the summer. Now add in the fact that you have less time due to a shorter day and you realize that you are really screwed.

You might think that a oversized system with a 1-1 ratio is the answer because you are not taking enough out of the bank to deeply discharge it. You are right until you get crap weather for days on end and that big bank does get deeply discharged. That's when you need a alternate source of charging to do the bulk and it too had better have the punch to get the job done.

[Cammalu]

So what kind of ratio do you all feel is ideal? 2 to 1?

[rvpopeye]

The maximum panels that fit and the smallest battery that still fills your "needs" without going below minimum charge before getting charged back up to full.

Then adjust your "needs" to fit.

So many variables.......impossible to just say "Do This" !

[Roadtripp]

Hello gang. 
 My flat mounted panels collect so much dust and dirt and they they don’t produce much power even when clean. On a little van it makes sense to place as many panels as will fit on top. And maybe a few to set on the ground too. Panels on a van will be easier to clean than a tall Motorhome. Finding some SunPower 21% efficient panels would be nice imho. If anyone finds a deal on some please let me know.

[justjim]

Check Santan solar

[sternwake]

Setting up and aiming portables is not always convenient. As much juice from the roof as possible, is a great starting point even if flat might yield a tiny fraction in winter.up north of what tilted can yield. And how i would restart from scratch if i were to do so.

Roof mounted.panels are almost always doing something, when its light out even if it is only powering a tiny load. That is a tiny load the battery is not having to power.

Portables with a good extension cord when safe and.convienent to employ can be a whole different charging system on its own solar controller and be extremely effective..especially when re aimed at the direct sun several times a day.

Roof panels can be made to tilt.
Mine can, yet I never do.

Panels facing morning sun make for happier batteries.
More is better. Permanent roof mount, or portable, and potentially both.

[GypsyDogs]

Check Santan solar

I misread that..

Satan Solar??
brings a whole new meaning to Fire Power... lol

[RoamingRaven]

I know your rig is larger than mine, but in the winter up north, I could run my onboard furnace off of solar for the night with little power left over in the morning. I have a large buddy heater that heated the rig perfect other than catching the pup's tails on fire which could have been disastrous. Scorched fur stinks. I left it for the kids to use if there is an outage. For my peace of mind and the pup's welfare, I'm sticking with the onboard furnace at this time.

[Cammalu]

I have a lot of solar but I just don’t know if there is enough.