Real World Results

[rjreiffer]

Hello all,

I am looking to find the experiences of those that are running heavy electric coaches using solar to find out what kind of experience they have had in:

• What is the charge rate on average on sunny days?
  What is the charge rate on average on cloudy days?
  I have heard some bragging about their solar panels will charge by moon light? Is this a bunch of bad stuff?
  How many panels are you using (and what is the length of your motorhome)?
  How many batteries are you using?
  What is the size of your inverter?

I know this is a lot to ask but just trying to get a handle on the practical side of solar (especially for those of us that live in the north and have lots of trees!)
Thanks in advance!

[sibe]

Basic system.. 4 100 watt panel, 30A controller, 300ah of lead .. 2000 pure sine inverter.

I have seen 1.7-5.1 amps on a cloudy day.. full sun direct overhead I hit 20.1 amps .. testing microwave for 10min.. 1200watt at 120.. after 10min, amps moved 15.6 to 18.2 as it replenished. hour later it was at 5amp 13.7v chging..

30 ft class c.. I can add atleast 5-6 more panels but this is a cheap first attempt to keep batteries up. $500 max on panels controller, wiring.

[hclarkx]

Originally Posted by rjreiffer

Hello all,

I am looking to find the experiences of those that are running heavy electric coaches using solar to find out what kind of experience they have had in:

• What is the charge rate on average on sunny days?
  What is the charge rate on average on cloudy days?
  I have heard some bragging about their solar panels will charge by moon light? Is this a bunch of bad stuff?
  How many panels are you using (and what is the length of your motorhome)?
  How many batteries are you using?
  What is the size of your inverter?

I know this is a lot to ask but just trying to get a handle on the practical side of solar (especially for those of us that live in the north and have lots of trees!)
Thanks in advance!

RJ, are you handy with a spreadsheet like Excel? If so, you might want to play with one that I've written. It uses solar and weather data from NREL's PVWatts on-line software to estimate energy use day by day for an electric fridge, propane heater motor, and an A/C (preferably a mini split). It spits out generator run events for each month for the size battery and solar array you input. I.e., evenings when you have to run a generator to have enough battery to get through the evening and night. It can also guide you through estimating miscellaneous loads if you don't already have a handle on that.

NREL is the National Renewable Energy Lab in Denver
PVWatts is NREL's solar production calculator.

PVWatts provides a *.csv file of hourly data which you copy into my spreadsheet.

[hclarkx]

Surprisingly few responses here .... so I'll add more:

The charge rate on sunny days is a sine wave. On clear days you will get around 12 hours of solar (longer in summer, shorter in winter) with the amount starting at zero, hitting max around noon, and zero at sunset. The pattern is half of a sinewave. What matters is the total Ah for the day. If you want to dig deeper, you can determine that value for any place in the USA for any time of the year with the aforementioned PVWatts.

On cloudy days the charge rate varies widely so there's no useful number we can provide. Maybe, on average, it's half the full-sun level. Wild guess. Again, PVWatts will provide statistically representative data for locations and times of the year of your choice. An immediate output of PVWatts is monthly totals. You can divide that by 30 to get daily average.

My solar controllers go to sleep when the solar level is not enough to generate some output. I've never seen even strong moonlight keep them awake but theoretically it's possible. But, surely not enough Ah to count.

My son's 34' motor home has ten 200W panels and 840 Ah of LiFePO4 battery. He runs a mini split A/C unit for up to nine hours per day along with lots of other electric devices. Only about 28 feet of his roof is available for panels (front slopes too much) but he was able to retain all skylights, ceiling fans, vents, etc. He did remove both A/C units since he has a mini split A/C. He plans a 12V 9+ cu ft electric fridge at some point.

My 30' fifth wheel has about 24' of usable roof. I can put 2200 Watts on this roof without sacrificing the bathroom skylight or any of the three roof vent fans. I did remove my A/C in favor of a mini split that is waiting to be installed. I have 300 Ah of LiFePO4 battery now but will have a bit over 700 when I add the mini split. The roof of my 5er slopes heavily toward the rear so I point the tail south when I can to get an extra 10-15% solar.

My son has a 3 kW inverter that powers everything including his Mini Split.

I currently have a 900W inverter which covers everything I currently have including a microwave. It's been in use for 7 years.

I do have a 9+ cu ft 12V fridge. I currently have 1000W of solar installed and will add about 1000W when/if I get around to installing the mini split A/C. I have an 1800W inverter waiting to be installed. The 900W inverter may power the mini-split but if it doesn't, the 1800W will be shared between the A/C and other loads.

Trees: You can break up your solar panels into groups each on its own solar controller to help combat shade from trees. Or use a parallel connection which is more tolerant of shade (unshaded panels are not hindered). If you will be moving fairly often (won't have a long string of days in the shade), a larger battery can help you ride through cloudy days or some shade. My own system is designed for late fall and early spring on the Central California coast (short days, some fog and clouds). This is my worst-case camping location and I have not used my generator in almost six years. In fact, I've only engaged my full 1000W of panels twice in the year since I added the 12V fridge and upgraded from 600W to 1000W. On typical days my batteries are back to 100% by noon on sunny days and by 3 pm on fairly cloudy days. On very cloudy days I may only get half way back to 100% but my fairly large battery will carry me through several such days and then take a day or two to get back to 100% when there's good sun.

I typically use about 100 Ah of energy between sunset and morning sun. I was using about 75 Ah but now it's 100 with the 12V fridge (which does not run very hard due to the cool nights along the coast. When I go inland and the fridge needs a lot of energy on hot days, I'm getting a lot more solar so it's easily covered, usually with only 600W enabled.

I started with 200W and lead-acid. Got the 300 Ah LiFePO4 battery and 400W but 400W was a bit marginal on occasion so I upgraded to 600W. I added another 400W to cover the 12V fridge (more than really needed though the margin is nice to have).

The type of battery you have makes a huge difference in how much solar you need. With lead-acid, including AGM, you need about 35% more than you will with LiFePO4 batteries. This has to do with the charge regimes of lead acid and LiFePO4 and that lead-acid has high losses when serving load or being charged that LiFePO4 does not. This is an often unrecognized benefit of LiFePO4 batteries.

I hope this helps.

[paul65k]

So I started out small and our system has grown over time.

Started with 1600W of solar driving our 660Ah of AGM batteries through Victron 150/100 MPPT and Victron BMV712 monitor. Candidly this was a pretty good set-up and I got everything installed for about $2K with a self-install, we already had the AGM batteries, a 2000W MSW factory-installed inverter, and a 7500W onboard generator. We were able to get our batteries charged mostly based on the weather but our usage was always monitored.

The next upgrade was after we removed the RV fridge and installed a residential unit. We installed 6 Lion Energy UT1300 LiFePO4 batteries leaving everything else in place and this made a huge difference as the batteries charged MUCH faster, mostly as a result of the charging profile of Lithium. The results were very good and we were able to keep the batteries charged up and live pretty well, but we still had to watch our usage or run the generator a couple of hours every other day or so...... additional cost was around $4500 (with cabling).

But that wasn't enough and we wanted to run everything in the coach like we were plugged in wherever we were, and we boondock over 90% of the time, soooooooo I removed the factory inverter and added the following items:

• Dual 24/3000/70 Victron Inverters (wired in Split Phase)
• Added 4 more UT1300 batteries (13300 Wh/540Ah@24V)
• Dual 24-12/70 converters (Servicing 12V bus including levelers)
• Dual 12-24/15 DC-DC converters (Charge Batteries with engine running)
• Victron Cerbo GX with Display (Allows monitoring via WiFi remotely)
• Rewired electrical panel to energize all circuits from the inverter(s)
• Added 220V subpanel for future multi-zone mini-split AC unit

The additional cost was around $6K

We now have a system that allows us to run one AC unit while driving (along with dash air) and still have excess charging going into the house bank or we can run both AC units (without the generator running) and have about 60Ah coming out of house bank. We also live like we are plugged in no matter where we are and rarely run the generator except to keep it exercised with the exception of running AC, but we try to follow the sun and keep our terms cool so typically we only need AC for an hour or 2 each day.

I don't think the total cost is really that high when you consider the capability and freedom this provides us in terms of where we can go and enjoy our coach. I specifically bought a coach that was a couple of years older so I would have the headroom to make this investment...... I can't imagine owning another RV in the future without this level of capability.

I hope this helps answer your questions

PS...This is addicting

[SJ-Chris]

Originally Posted by paul65k

PS...This is addicting

LOL....YES, I agree 100%!


I've got just a small solar system that I added along with inverter. Fun stuff. Very simple. Now I'm always thinking about solar, charging, etc and occasionally find myself looking for solar deals even though I don't need any more solar...lol


-Chris

[sibe]

Cool System... the Cadillac of Solar...
Personally I can't push myself to the cost of Lithium Batteries... Not yet anyway...
My system is small , gonna add another 200 watts.. for 600 total.. as I have 300ah but acid,,, That will max controller and wiring,, I can easily add another 800 or more up front if I pack them with another controller to feed system..
I have room for 8 group 29/31 size batterys 6 with ease, 2 would have to be in original compartment..

I have already run 4/0 cable already to a bus.. I have 2/0 going to a 2000w inv.. it is 18inch from bus.. short cables,

DUH this is addicting just thinking.. I tried to add on stuff just incase...

I just dont use RV enough..but everyplace I do go is primative, no power etc.. I use genny, carry a 1000 or 2000 quiet when I need to charge only.. I also have a3500 quiet I take when AC time,,, as the onan4000 I have has been made quiet but fuel hog...I can run 3500 on 5-6 gallons in 24 hr on 85 degree day or 10 gallons or so on the onan.. I stay remote as nosie is never issue..even to me.. LOL

I do like the little Solar 400+watts,, I have now .. on nice days, no AC I can get by for 12-14 hours or so with fridge on propane.. TV on, laptop, small fan , nite light etc.. .. actually on last sunny day,, I left TV on for dogs.. all day and till 1 AM.. small fan.. fridge has inside and plenum fans..
Cell on and router..
made small pot of coffee in am and I was still over 60% at 8am.. next day was semi cloudy,Tv was on and we got to 80% +

I am getting to involved,, LOL

Originally Posted by paul65k

So I started out small and our system has grown over time.

Started with 1600W of solar driving our 660Ah of AGM batteries through Victron 150/100 MPPT and Victron BMV712 monitor. Candidly this was a pretty good set-up and I got everything installed for about $2K with a self-install, we already had the AGM batteries, a 2000W MSW factory-installed inverter, and a 7500W onboard generator. We were able to get our batteries charged mostly based on the weather but our usage was always monitored.

The next upgrade was after we removed the RV fridge and installed a residential unit. We installed 6 Lion Energy UT1300 LiFePO4 batteries leaving everything else in place and this made a huge difference as the batteries charged MUCH faster, mostly as a result of the charging profile of Lithium. The results were very good and we were able to keep the batteries charged up and live pretty well, but we still had to watch our usage or run the generator a couple of hours every other day or so...... additional cost was around $4500 (with cabling).

But that wasn't enough and we wanted to run everything in the coach like we were plugged in wherever we were, and we boondock over 90% of the time, soooooooo I removed the factory inverter and added the following items:

• Dual 24/3000/70 Victron Inverters (wired in Split Phase)
• Added 4 more UT1300 batteries (13300 Wh/540Ah@24V)
• Dual 24-12/70 converters (Servicing 12V bus including levelers)
• Dual 12-24/15 DC-DC converters (Charge Batteries with engine running)
• Victron Cerbo GX with Display (Allows monitoring via WiFi remotely)
• Rewired electrical panel to energize all circuits from the inverter(s)
• Added 220V subpanel for future multi-zone mini-split AC unit

The additional cost was around $6K

We now have a system that allows us to run one AC unit while driving (along with dash air) and still have excess charging going into the house bank or we can run both AC units (without the generator running) and have about 60Ah coming out of house bank. We also live like we are plugged in no matter where we are and rarely run the generator except to keep it exercised with the exception of running AC, but we try to follow the sun and keep our terms cool so typically we only need AC for an hour or 2 each day.

I don't think the total cost is really that high when you consider the capability and freedom this provides us in terms of where we can go and enjoy our coach. I specifically bought a coach that was a couple of years older so I would have the headroom to make this investment...... I can't imagine owning another RV in the future without this level of capability.

I hope this helps answer your questions

PS...This is addicting