My initial foray into Solar Power

Ever since buying Uma, the URRV, I've explored and researched the use of Solar Panels to provide electrical power to the RV.

I'd resisted going with permanent panels, mounted on the roof as associated costs were seen with very little ROI given projected days of use.  In other words, easier to run the old but still working Honda eu1000i generator for when I needed power to charge up the on board house battery and power/charge my electronics for work.

This last boondocking session, saw the Honda generator burning through a lot of oil.  So I'd begun thinking about replacing it perhaps as the cost of a ring job on the generator might not be worth it as opposed to buying a new one from Harbor Freight for $450.

I'd also previously calculated that I needed 5.5 Amps/hour from either a generator or solar panels to

• Power the RV refrigerator while its in propane mode.
• Charge/Power the electronics (laptop in docking station, charge phones, weboost cellular booster) via the 600 Watt inverter already in place.
• Power the LED lights as needed.
• Run the bathroom fan as needed.
• Run the water pump during warm weather glamping.

All of the above and at end of day when the sun sets, still have a fully charged house battery to carry on through the night hours, powering the fridge in propane mode and providing power for lights.  The electronics, would be fully charged as well and would be on their respective batteries for the night.

So, over next few weeks, as we camp in the URRV, we'll be using this setup:

From Harbor Freight, their Thunderbolt 100 Watt, four solar panel kit with included charge controller and wiring components:

image source: Harbor Freight

Overall construction seems pretty sturdy, but I splurged and paid an extra $30 to cover it for one year past the initial 90 day warranty provided by manufacturer.

Assembly was easy and mostly intuitive.  Operation seems simple enough but we'll see in the long run.

It's got a float mode of 13.8 volts and a Boost mode of 14.4V, we'll see how that works as well in reality.

Testing will tell if I can use it to do all the above and have a fully charged house battery at the end of the day, I've doubts on 100 watts being enough.

I'm thinking, right now, to use and move it as required for good sun exposure and not mount it permanently for now.  Also, my house battery is on its last legs so we'll see how I can stretch its life out while I explore solar panel technology.

Sunday Testing.

Took the above solar panel kit over to the RV storage yard where we keep Uma, the URRV and set up the panels up on the roof.  I think a setup location at ground level will be easier of course as you don't have to haul the panels up to the roof but it was all quite doable.  About 13-15 minutes to setup the whole thing and to tear it down as well for travel.

So far, the results are quite satisfactory.  I believe, given good sunlight, I can run everything I need, when boondocking, and still have enough battery capacity remaining to power the fridge in propane mode overnight.

Some power usage notes:​

Using boost setting on the solar panel charge controller (14.4)

13.2 Volts at inside meter

13.4 Volts at battery

For reference, when on shore power, it usually reads between 13.3V and 13.5V as

that's what the converter is set to provide.

Fridge on Propane mode - Worked OK

Electronics:

Amp/Watt draw from inverter:

Tv and weboost powered - killawatt reports .36a or 24watt

Note: I used the TV to simulate power draw of my laptop, which I forgot to bring 

along.

Add camera charging: .4 Amp or  26 Watts

Add iphone charging:  .46 Amp 31.5w  (Highest utilization I saw was 

32 Watts via Inverter)

Water Pump: Went from 13.2 to 12.3 when pump was on.

Turning on all the LED lights along with above (- water pump) caused the 

voltmeter inside to go from 13.2 to 12.5

After 90 minutes, the house battery read 12.6 after turning everything off.  

This figure isn't truly accurate of course since the battery wasn't "at rest".

Update:

Further testing Notes.

Whether flat or tilted, the difference is minimally higher when tilted, so probably best (when setup on the roof of the RV) to leave them flat to avoid the wind catching them and sending them flying.

Brightness of sun (duh) drives how much power delivered.  Solid overcast conditions resulted in barely 12.5V reported at the charge controller but it did "seem" to be delivering a small charge to the battery (with the battery isolated from all drains and inverter off)...otherwise with stuff on, the battery was being drained.

So far, in strong sunlight, a reading of 13.7V at the charge controller is best performance seen so far.  That showed an inside voltmeter reading of 13.3, with fridge running and electronics on.

Pretty certain the existing house battery is damaged in terms of capacity due to repeated drawing down of voltage previously.  Soon as it dies completely, I'll be looking to replace it.