stealth solar install on van

[dnix71]

You can't see it just standing around. It's a 120 watt Kocyera
http://www.ebay.com/itm/201284998460 bought on ebay.
Maximum Power: 120 watts
Maximum Power Voltage: 16.9 volts
Maximum Power Current: 7.10 amps
Open Circuit Voltage: 21.5 Voc
Short-circuit Current: 7.45 amps

Dimensions (LxWxD): 56.1" x 25.7" x 2.2" (1425 x 653 x 59 mm)
Weight: 26.3 lbs (11.95 kg)

It's a beast of a panel for charging 12v systems. It's hooked up to a PWM charge controller and a cheap 12v 17ah SLA. The van has dual a/c radio with a cigarette lighter on the driver's side for the second row of passengers. I hooked the battery/charge output by hardwire to the small 12v battery and then went with a cigarette lighter plug to backfeed the main battery. The smaller battery hardwired is to protect the charge controller in case of a blown fuse or if the main battery cable feed comes loose.

The panel is riveted to an L shaped aluminum rail, which is screwed down where a roof rack member was. The front of the panel is secured under another roof rack member, with peel and stick foam tape to keep it from scratching the roof or catching air.

The vent is after market and lets hot air out of the van.

With that much panel I will be looking for a deal on a deep cycle battery to replace the small SLA.

[madlabs]

Have you seen how much power they put out, flat like that? I'm going to be building an expedition van soon so I'm curious.

JOnathan

[dnix71]

Hard to say. It holds my car battery at 13.0 in overcast skies just before sundown. The voltage is low for grid tie, but perfect for a pwm controller. I don't notice any drag or steering drift from it mounted flat. The windscreen deflects the air up over the area where the front edge of the panel is.

If the panel had been a little shorter I would have bought two and mounted them sideways. A pair of 100's in series to double the voltage with an mppt would be nice.

[madlabs]

Keep an eye on it and let us know if you come up with some idea of output. I may see what a panel I have does flat.

Jonathan

[dnix71]

I just ordered another inline dc watt meter. I couldn't find the one I thought I still had.

[madlabs]

Great! I'll be looking forward to some data. Would be nice if they did ok, I'd like to have them mounted flat most of the time with a tilt option if needed for more power.

Jonathan

[bart]

   I've been using one of these for monitoring a Headway lithium battery pack. Out of the box it works very well.
http://www.amazon.com/gp/product/B00EYZS6R6?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00

[dnix71]

bart The one I ordered from eBay is $1 more.
http://www.ebay.com/itm/150-Amp-Watt-Meter-with-box-HEAVY-AWG-WIRE-4-HI-AMPS-Solar-Wind-Turbine/371141580880
The exact same meter from a different eBay seller whose name begins with "Hurricane" would have been my purchase except that the seller block me from buying.

[bart]

   While that looks like a nice meter, it is from Missouri, Wind, and Solar. Famous for the car alternator wind gennies. Drive by there once in a while. And keep driving.

[MattM]

I imagine a semi trailer would be more ideal for augmented living on the road.  Probably wouldn't boost fuel mileage with any relevance, but for couples that drive together it would keep them supplied with regular battery power.  Maybe with the right insulation it would sustain a refrigerator truck.

[madlabs]

For me, ground clearance and FWD is more important than comfort. :-) So no semi trailers for me.

As to fridges, my plan is to gut a small dorm fridge and make a combination ice box/fridge. Lots of insulation, good drainage, access from the top.

Jonathan

[dnix71]

Short report. The max wattage I have seen is about 20, but that was from parking it in the sun and with the engine off, starting the inverter and a/c. Otherwise it was about 16 watts. I'm seeing over 100 watt hours a week, but I don't know how well the power meter actually correctly reads the pwm output of the controller. My dash voltage controller samples every few seconds and misses some events. Sometimes it sees the voltage drop when cranking, but it the engine starts fast enough it misses it.

Last week the van battery died. I thought it was a bad diode on the alternator as the battery was going dead overnight. Turns out the solar panel was preventing the battery from dying during the day. The strain of running the a/c from the inverter may have hastened the battery's death. Maybe not, it's been a brutally hot summer here, heat kills batteries.

Good news is that the battery was only 22 months old and a premium battery from a major chain. They tested it thoroughly and then replaced it free.

With the new battery and a dash plugin volt meter it's much easier to not stall the inverter sitting in traffic. No I can see when the alternator stops charging completely and rev up the engine a bit to bring it back.

Before the battery replacement I was seeing system voltages above 15 with the engine off. Now it's rarely above 13. The van sits in the shade of a tree at work until about 3pm. If it's sunny late in the afternoon then the voltage creeps up to maybe 13.5.  Engine running the system voltage is 14.5 when cold and drops to about 14.2 after a few minutes even with the a/c running.

[Ungrounded Lightning Rod]

Have you seen how much power they put out, flat like that? I'm going to be building an expedition van soon so I'm curious.

JOnathan

That will vary depending on your latitude and the season.  With solar panels the open circuit voltage is dependent on temperature, the max current is dependent on illumination (of the least-illuminated cells in the string), and the power is a function of those, the load, and the metalization and wiring resistance.

You can compute an approximation easily enough, given your latitude and the panel's nameplate ratings.  The cosine function is your friend.

[MattM]

The vibration during driving may have weakened some solder tabs?