Built A tiny home, but it has solar issues

[The_realTW]

Hey guys, I found the video on the instructions to my MPPT SCC, the language is TAGALOG, feel free to check it out!


btw I’m reading my second solar book now, starting to get a real handle on all of this

https://m.youtube.com/watch?v=YxUT9L4_Fxs

[The_realTW]

It is. The "Look inside option" on Amazon's website is pretty fair how the rest of the book goes.

I read the sample, some of it is review , other pieces looked helpful! I also like that other book!

[chrisski]

For $10 a month, you could down load "Off Grid Solar Power: How to Design and Install a Mobile Solar System for RVs, Vans, Boats and Tiny Homes " and "Mobile Solar Made Easy" and "DIY Mobile Solar Power 2020: The Complete Guide To 12 Volt Mobile Solar Power For Rv's, Boats, Vans, And Cars " at no additional cost plus about a dozen more.

Since I'm a member, I don't see subscription deals, but I would not be surprised if it was $5 per month for the first couple of months.

[The_realTW]

Chrisski i really like this one, and it’s 5 bucks on kindle, seems to be the next logical step

https://www.amazon.com/dp/B08P3Q94KJ/

[chrisski]

oh btw is it the book by William Errol Prowse?

It is. The "Look inside option" on Amazon's website is pretty fair how the rest of the book goes.

[The_realTW]

I do think you're on the right track.

"Mobile Solar Made Easy" is available for download at no extra cost if you have Kindle Unlimited. Honestly though, now that you're getting a plan and moving forward, you might find a lot of the book too basic. It's a good book that explains what an inverter is, a solar charge controller, but it won't tell you specifically what inverter to buy along with the brand of panels or gauge of wires to install. It says in a paragraph to get electricity from the roof to the battery bank, you'll need to drill a hole and use a gland. Never having drilled a hole in my RV, there was quite a bit of research I did before I drilled.

I'm not sure the splitter caused the power loss. From this link, Mixing solar panels – Dos and Don’ts – SOLAR POWER SECRETS (solarpanelsvenue.com) I think it was like this example, only with two panels instead of 4.
Differrent Sized Panels in Series.jpg
And this is an example of a mismatch in parallel:

Differrent Sized Panels in Parallel.jpg

I think your installer may have been experienced with house installations where someone else did all the design work, and what he did was follow the plan. I think he may of struck out on his own too early with some spare parts he had lying around.

I suspect your right on many counts, all we can do is look forward not backwards.

oh btw is it the book by William Errol Prowse?

i do understand tue fundamentals, I doubt there will be a book that will give me a specific shopping list, that’s probably where you guys come in , I’ll figure out by usage somehow, evaluate the damages and any issues with the current system, then rebuild from there!

[chrisski]

I do think you're on the right track.

"Mobile Solar Made Easy" is available for download at no extra cost if you have Kindle Unlimited. Honestly though, now that you're getting a plan and moving forward, you might find a lot of the book too basic. It's a good book that explains what an inverter is, a solar charge controller, but it won't tell you specifically what inverter to buy along with the brand of panels or gauge of wires to install. It says in a paragraph to get electricity from the roof to the battery bank, you'll need to drill a hole and use a gland. Never having drilled a hole in my RV, there was quite a bit of research I did before I drilled.

I'm not sure the splitter caused the power loss. From this link, Mixing solar panels – Dos and Don’ts – SOLAR POWER SECRETS (solarpanelsvenue.com) I think it was like this example, only with two panels instead of 4.
Differrent Sized Panels in Series.jpg
And this is an example of a mismatch in parallel:

Differrent Sized Panels in Parallel.jpg

I think your installer may have been experienced with house installations where someone else did all the design work, and what he did was follow the plan. I think he may of struck out on his own too early with some spare parts he had lying around.

[The_realTW]

Before I begin I want to say I believe the issues with the system are a combination of things. I will not place 100% blame (or even assign a value) on my former solar contractor, however i will say it should have been his business to know this system would never work the way I needed it to. It looked pretty and cost a bundle but would always have been inefficient for my needs. The system failure was only a matter of time. It was always from the moment he hooked it up, a ticking time bomb.




I now know that my system is a 325 watt active panel feeding parallel into the charge controller at a maximum of 50 amps with an average voltage of 23-30 bolts depending on the angle of the sun. The batteries are 400 AH @ 6 volts - 20% efficiency loss = 320 AH. That 320 AH can generate 1.92 KWh of energy. The energy in the batteries that is placed there through the SCC is fed back into the power center through the 3500 watt inverter.




The issue is without knowing my exact power needs it’s impossible to know if the KWh usage (watt hour x 1000 =kWh) over any given day , coupled with the power collected by the panel (which is highly dependent on the atmosphere) is enough to sustain the system. Also at issue is the unknown draw a large inverter like that takes to run when not under load. The waste from the inverter is kind of like leaving a car idling. Nothing is on but the gas is still being used.




At this point I would say that even on the hottest day of the year (I should say sunniest because solar performs better in the cold actually) the power coming off that one panel was/is never enough to fully replenish the 400AH that would be depleted. In addition as the solar went lower day after day, the batteries reached an unsafe level.




While cold weather is great for solar due to the thinner atmosphere, the same thing cannot be said for the batteries. Once the batteries reached an SOC of 30% the acid levels were dangerously low and mostly water. It’s likely that water froze to ice when the tiny home was driven to Nebraska.




Going forward I need to look at the following



Expansion of available solar collection (panels)
Relocating the batteries
Downsizing inverters
A full energy audit to determine the duty cycle and the usage needs of everything on board the tiny home.




A final issue that is above my knowledge is the panel defined as the “helper” panel is most likely a mismatch to the larger panel, and I suspect this caused a negative resistance that further compounded the energy issue coming from the panels. One could say the system ran better with the one panel alone. As we all know resistance is never a good thing as it translates to heat. My guess is that “helper” panel was causing a negative solar collection. The panel was collecting the energy but the resistance stopped it from making it to the SCC. Best guess is 25% or possibly more was being wasted at the MC4 splitter.




Ok I sound smart lol but I’m still learning!




At least someone comment and let me know if I’m on the right track now.




Oh btw I forgot I did finish the solar for dummies (obviously) I skipped the chapters on financial and rebates, otherwise I read it all. Probably going to pick up another one geared more to off grid and tiny homes (any suggestions would be welcome)

[The_realTW]

Heads up, it is suspected this is the panel that is currently on top (the main panel, no idea on the tiny one)

https://www.solarelectricsupply.com/...tt-solar-panel

Edit: spoke to soon, this is the “helper panel” , I’m certain pf it since he stayed in the office and I made new holes to mount this one.

the original install was supposed to take 4 hours and it took him 3 days, so I figured if I put this one on it would speed up the process, and I had this one up in 20 minutes.

https://www.amazon.com/dp/B07HQBN9WH/ref=cm_sw_r_cp_api_glt_fabc_WK3R5MP987FY9R56011F?_ encoding=UTF8&psc=1

[The_realTW]

I Just wanted to let everybody know that around page 252 of the Solar book I started to finally see the answers. Before that I learned how to install a solar powered waterfall , a solar powered cattle feeding system ,a solar powered attic fan , a solar powered heating cover for my swimming pool , solar powered heater for my home and numerous other things ,however finally at page 252 and starts talking about batteries , combined ,power duty cycle , amps needed , the things that I really needed to begin with.

it was a long slog, but I am starting to understand the ways I can do this right now.

Also real quick it talked about contractors, getting references, and getting everything in writing, which I didnt.

I have been talking with my Welder as well about redoing the setup, issue still remains the tent cant be moved, so its either going to be some sort of Parallel system that would use the existing panel and have portable panels to augment that, or it would mean building out the roof to support more panel.

Funny thing is I did quick "from memory" audit in my head, and if I ditched the microwave and the AC unit, I could probably be fine as is. I do want to incorporate a system that will allow me to use them however, so I know some more computations are ahead.

Thats the update!

[The_realTW]

Kudos again seem due Sunking. The legacy stays productive even when he's mostly absent. Others have benefitted much as you have from his efforts.

That man is a genius, I wish he had designed my system, but if he had I never would have met all you wonderful people!

[The_realTW]

EDIT: I guess bullet points and the like do not work on this forum grrrr

Ok Everyone

The following is being written with little more understanding in this technology, thanks to you guys and your patience. Obviously I cannot do an energy audit right now, however I am still trying to get a firm grip on the situation, here is my "prospective plan" for future solar.

Keep The existing panel on top of the tiny home (325 watts)

After I identify this panels "specs" purchase a "suitcase solar" portable set of panels that would allow 350-400 watts optimal solar collection (in addition to the 325 on the roof)

use existing MC4 connector to wire a "splitter" into the main solar run to the SCC, this split would be used when stationary to hook up the portable panels.

changeout the existing "oversized" inverter for something within my range, I am not sure what this would be however, as I have yet to find an inverter with outputs to my power panel, although I am sure some could be homemade if necessary

THe new inverter would be somewhere around 1000-1500 watts??? and that should work better with my panels

I can either keep the existing batteries if they can be brought back to life, or change them for AGM batteries, but as I understand it, lesser AH will mean lesser reserve solar capacity during "dark" hours

My total "optimal" collected radiance should be 325W +400W= 725W - 20% loss in system = 580 watts total collected, after this I start losing my way, but I hope this will

Resolve the "space" issue with installing new panels on the roof

minimize the " to large" inverter that is probably eating up my collected storage

look to other solutions after a successful audit

Ok I confess I did not read my solar book today, as I was getting a root canal, cant be all fun in paradise. I tell ya, if I had a wind generator down here, I would have unlimited power! lol

Anyway more as it comes to me!

BTW anyone, if your reading this and need background, visit the first post of this thread for a detailed walkthrough of my current system and its inconsistencies

[chrisski]

I think the “Solar Off Grid Battery Design” is very good. A lot fo questions are skied about how many panels do I need? On another forum, I include a link to that thread.

[J.P.M.]

BTW, I read this and this last night, and while I do not understand everything, this guy spoke to me more then my solar "expert" ever did. I learned in one long spiel about why my system never worked.

400AH batteries being charged by a 325watt panel using a 3500 watt inverter......

hmmm yeah no lol

Kudos again seem due Sunking. The legacy stays productive even when he's mostly absent. Others have benefitted much as you have from his efforts.

[The_realTW]

BTW, I read this and this last night, and while I do not understand everything, this guy spoke to me more then my solar "expert" ever did. I learned in one long spiel about why my system never worked.

400AH batteries being charged by a 325watt panel using a 3500 watt inverter......

hmmm yeah no lol