Sunday, March 11, 2018

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


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 

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".


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.


RichardM said...

That kit still seems expensive to me. And a hassle to set up as opposed to something that you install once and you're done. And the monocrystalline panels are smaller than the polycrystalline ones.

Just my opinion...

Still seems to be a good option to replacing the Honda. I'm looking forward to your next boondocking trip!

CCjon said...

Dom, Interesting find at HF. Is there a way to anchor it on the roof so the winds don't remove it?

redlegsrides said...

What you mention might be in my future but I see this as a “cheap” way to get a feel for what will work for us.

redlegsrides said...

It does come with permanent mounting hardware, Jan, but it wouldn’t be too not planning on using it in permanent mounting mode least not yet. I am loathe to punch more holes in the roof. While boondocking I plan to simply set it up near the RV and move it as needed.

redlegsrides said...

Sorry, I meant to write that it does not come with mounting hardware.

RichardM said...

Plus, there is a benefit to the portable panel. If you are camped in the shade (say on a warm, sunny day), you can just put the panel in the sun and leave the RV in the shade. Also, you can catch the shallow rays of the early morning or late afternoon sun. Permanent panels miss out on those potential watts.

redlegsrides said...

RichardM, that's the idea anyways, being able to move the panels to the sunny side of the RV...more to follow, am curious to see if enough wire is provided.

RichardM said...

Since this setup is only 5 amps or so, it’ll be easy and cheap to add length if the charge controller is relocated to the RV. Then the controller can more accurately sense the battery voltage. Voltage drop between the panel and the controller is less critical as their open circuit voltage is usually something like 18 VDC.

redlegsrides said...

RichardM, supposedly, max output is 6.8 Amps. Good to hear extending the length of the wire from the panels should be easy. Apparently, you can also buy a "hub" to link three more sets of panels together with the one I have already, am sure a new charge controller would be involved of course.