Handy solar info for lead acid batteries

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pianotuna wrote:
Some of handy bob is dead wrong. I've included a much better less wordy and less opinionated link below.

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT. What ever type of controller is chosen, make sure it has adjustable set points and a temperature probe that is on the battery.

If you use solar as a battery charger, one rule of thumb is between 60 and 150 watts of panels per 100 amp-hours of storage. The smaller the battery bank the higher the wattage needed (per 100 amp-hours). Here is a link to the rather special spreadsheet which includes an energy audit, that N8GS has created to help size solar battery charging systems!
solar spreadsheet by N8GS

If you full time or use an inverter lots, then populate the entire unshaded area of the roof with panels. I'm considering replacing my awning with solar panels.

For a nice explanation of solar, try this link:
Golden rules of solar

Most of the criticism I've heard about Handy Bob is his info is very out of date. He does cover the basics well and is a good start to learn about basic solar.

While Bob may not be well organized with bullet points or even standard multi-paragraph composition it covers a lot of issues and is thorough almost to a fault.

My biggest take away is that a few cut corners or minor short cuts can have a dramatic effect on overall performance.

pianotuna wrote:
You forgot the word "Some". And yes some of it is wrong. That misleads solar beginners. His ideas could be summed up in five short paragraphs instead of going on and on and on.

Joel_T wrote:
"...dead wrong." ???

Well, help folks out, what do you deem "wrong" in his info?

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I like Bob's appreciation of Morningstar controllers.

I think that "dead wrong" is a bit hyperbolic. By and large his major tenets are large enough wiring for minimal voltage drop, charging at the BATTERY manufacturer's spec'd voltage, measure voltage at the batteries and use a decent controller.

Not exactly controversial ideas.

Part of the problem with charging batteries is that the only voltage that matters to the battery is the difference between it's current voltage and the charge voltage.

Taking 12.5 as an example and simplifying things, if your charge voltage is 14V and you have a 3% drop to the batteries (-0.42V) you are losing 0.42V/(14V-12.5V) = 0.28 or 28% of your potential energy that could be going into the batteries.

JiminDenver wrote:
My solar is a generator, not a battery charger.

I'm parked on BLM land next to someone who has to run his generator in the morning and again all evening, presumably to watch TV. He has one small portable panel. I'm planning on moving.

I wish more boondockers had sufficient solar and an inverter.

Not sure why 'lead acid batteries' is in the post title.

Roys concept of solar is used by others on the forum. Mine however you won't find on any blog. In fact most would tell you that it can't be done at all.

My solar is a generator, not a battery charger. It is a big enough generator that we run a small air conditioner, cook, heat water and much more without the batteries knowing that the gear is even running. Minimal cycling means that my batteries will last much longer than if the were deeply discharged and recharged daily. It's a different way of looking at it and you are not going to see it in any blog.

Jacks site is good and you can talk to him on RV Dreams any time. I started reading three years ago and haven't stopped yet.