Yes it could have been more clear that you were using a standard 12 volts but I still don't think your math works.
3500 watts of solar, at 12 volts, does indeed come out to almost 300 amps but the but that is theoretical maximum which only exists on paper. It assumes the sun is directly perpendicular to the panel (only happens on the equator or with "tilt a whirls"), the panel is perfectly clean, and there is no obfuscation in the atmosphere. With flat mounted panels there is zero opportunity to meet any of these requirements unless sitting directly on the equator.
While you de-rated the panel output, you didn't de-rate sufficiently to account to all the factors mentioned above. While the period of astronomical noon +/- and hour might need be de-rated only 20 or 30% due to angular inefficiency, dirt, atmospheric conditions, etc. the rest of the light available is going to be converted far at far closer to 40 or 50% efficiency thus requiring a 50 or 60% de-rating.
So, I plugged in Austin Texas to a PV calculator with the following system parameters:
12 VDC panels, 3,500 watt panel output, flat mounted (0 tilt), 14% system losses and 96% inverter efficiency.
The total ANNUAL kWh is only 4,702.
The highest month output is July 533 kWh for the MONTH which is 17.2 kWh per day. In December the output is 7.45kWh per day.
Totally agree. Human nature what it is, very few people with a manual tilt system are going to employ it let alone keep adjusting it to get maximum benefit. In super high latitudes a manual tilt can be quite effective as the sun never gets high. Heck in Alaska the sun never gets high enough to rise for how long each year? Since we're wanting to enjoy Alaska and Canada but I know I'm not going to tilt things, we'll just be buying more generator fuel when our driving doesn't recharge the house batteries (via second dedicated alternator).
I'm not sure I can agree there. While I was initially planning for 1/2 of a Nissan leaf reconfigured and with a BMS installed, INSURANCE is an issue. We met a skoolie couple on the road. After a direct strike by lightening their electrical system fried and the batteries started a fire. This wouldn't be unusual for ANY battery with a lot of juice after a direct strike but because they built up their own battery, the insurance denied their claim.
So if you can't afford to lose everything in your skoolie and take the financial hit, batteries need to be factory items.
I am not going to divulge the source (until we get ours) but there is a current battery on the market with 5.1 kWh of lithium, built in BMS and circuit breaker as well as com provisions for remote monitoring that is just $1500. In a 12 VDC system that's 425ah and $3.53 per amp hour....for a battery with warranty and the all important financial protection over home built.
It's also insanely compact at 100 pounds, and has great reviews. We're going with two.
Four Battleborns @ $800ea (I think they're 900-1000) would bring only 4.8kW at a cost of $3200.
Of course there's shipping unless you can pick them up yourself.
I'm chill, just having some mathematical and engineering type discussion. Nothing personal, just discussing the topic. At least on this end, I think you brought up good points as well.
I think you're right about bias. And that's fine we all have them, the difference is whether we realize it.
Turbines aren't for everyone but here's why we're going to eventually have one or two in our build and so we're planning that from the start so the infrastructure is there. On the coast in Oregon, there is almost always a lot of wind but the sun is an elusive creature, sometimes for weeks upon weeks.
The typical wind speed on the coast where we go is sufficient to drive a 400W turbine to it's 400W production speed. Since the wind blows 24/7 that comes out to 9.6kW, even if it only produces 3kW, that's probably sufficient for our needs on the coast as electrical needs there are minuscule.
As for the 180 mph leaf blower only getting the turbine to produce 8.5W, that 180mph marketing point is at the exit and dissipates rapidly. It's also not going to apply that "wind" to the entire turbine blade surface, and so I wouldn't expect it to produce much of anything other than damage to the turbine. Now a WIND TUNNEL that had a mass of air sufficient to impact the entire blade disk, that would do, so long as it was of sufficient diameter to avoid creating a "shroud" effect.
And OH YES, the folks that think running a turbine, alternator, wheel on the ground, etc. for "free energy"..... I don't think they ever rode a bicycle with a mechanical generator for the lights which flipped over against the tire when needed. Even those little guys you could tell were dragging and making you work harder.
Hope what I've written makes sense, particularly the PV calcs for Texas.
