Recommendations for 100w Solar Panel

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I fit panel->isolator (can be a fuse, >15A DC Switch, PV Switch-Disconnect or DC MCB) -> solar controller -> (DC MCB/Fuse -> Battery) x 2.

Always turn solar off first before controller and controller on first before solar to keep all your magic smoke inside the controller.

My 45A solar controller accepts 150A cables...that's some commendable product design.

jace_da_face wrote: »

Has anybody tried flexible solar panels? Something like this?

Eh yeah I fit them on boats. Peel and stick onto polycarbonate. Works grand for neutral orientation on a moving foundation.

I don't recommend them for campers, more expensive and less output.
Due to the lack of a rear-side air gap they derate faster as the van roof heat sinks them.

My panel is on a roof rack. No holes and tilt adjustable with storage underneath.

huddlejonny wrote: »

1 x LED Voltameter..................... €1.90

Any links?

My 150Wp flat mounted today, is powering this post with watts to spare.
Everything is fully charged I've been touring 17 days. Last plugged in 6 weeks ago. :cool:

That voltmeter might not be as useful as you'd hoped.

Blue is quite hard to read in daylight and blue beside red makes your eyeballs go 3d vision and hard to focus..at least they do mine.

Amazon wrote:

Allowable error: 1% (+ /-1)

This means ± 0.12V ( plus or minus least significant digit) so if your voltmeter displays 12.4V (70% SOC at rest) your battery could be either 12.3V (60% SOC at rest) or 12.5V (80% SOC at rest).
Say you only use 50% of your battery as is normal accepted practice then this 20% disparity is amplified to 40% inaccuracy over operational range when using it as a state of charge meter.

Compounded by the fact solar means your battery is never at rest it's an altogether inaccurate way to measure capacity and merely the first third of the equation being pressure x rate x time = available power (Volts x amps x time). The other two missing ingredients are current (rate) and time (duration).

When you can read amps also, you see the current of your base load parasitics, your running appliances, your charge rate from PV and alternator and you can far more accurately dead reckon amp hours. Adding a ~250A shunted ammeter is a very inexpensive step to managing your available power. With both voltage and current you can see the watts in and out of the battery.
For calculated capacity over time or state of charge more sophisticated metering is required which start at the >€100 range. These are called battery monitors, while I recommend them as a precursor to any other electrical modification I don't think anyone has heeded me on that one. I think they are invaluable and worth the money..

To get the most outtov your voltmeter wire it through a switch on it's own dedicated conductor pair fused at the battery on the positive on 2 core 1.5mm² with a 100mA fuse.

If it has a trimmer you can adjust this with a plastic tool using a reference multimeter with better accuracy to calibrate the voltmeter to the same values. I find 1 in 2 cheap and cheerful Chinese jobs acceptably accurate after adjusting this.




Also available in these flavours;



I also find that switching supplies including ones integrated in LED MR16 lamps drive the Chinese Voltmeters crackt and they can be another volt or two out when the switching supply/light is running.

In any case I'd use a digital multimeter in the van for a few days to verify the fidelity of any cheap meter I install across it's operational range. Then I file it in the art basket if it's not up to tolerance, for a primary meter I deem that 0.3% accuracy @ 12V.

Maybe Bob can explain it better (and grumpier).

William Thompson, Lord Kelvin wrote:

If you can't measure it you can't improve it.