max cottrell

It's been a looong time since I posted here but I thought this might be something worth your time to read. Background: We have an off grid tiny home in northern Michigan I spend the summer at that I put a greenhouse at. I've been transplanting my crops 45 days ahead of last frost and getting bumper crops each year. Keeps the animals out too. Our year round home is a condo so any crop growing needs to happen indoors.

So, I needed to start this years seeds and looking at the germination temps for various seeds, I thought I'd need something better than a starting tray and a mat and wanted to do a better job of starting them than last year's utter failure. Enter the home made spare bedroom greenhouse. I've started my peppers, tomatoes, cucumbers and broccoli with great success. Best part is this can be expanded to as many shelving units as you want.

1. I took one of my many spare plastic storage shelves (4 level snap together) and used shrink film window plastic with the 2 sided tape, wrapped the shelving in the plastic all the way around. Didn't shrink it, left it sorta loose.

2. Grabbed a small space heater, some PVC tubing from an old water heater exhaust, hooked it to the the PVC with a vent for each level of shelf. Keeps the greenhouse at 80-90 degrees.

3. Mounted LED grow lights on the bottoms of the shelves.

4. Put the heat mats on one level for higher temp. germination seeds. Easy to keep the soil nice and warm.

5. The plastic on the front facing side can be just pulled away from the tape and restuck when done.

6. I'm using a cordless garden sprayer for watering. Man, that works great!

Next winter, I'm expanding to 4 shelving units and cutting the center of one shelf so I have 36 inch high growth space for growing veggies next winter.

The manufacturer has sent me an updated set of remote controls for the lights. Apparently, there are a significant number of abilities that the lights have that aren't being used.

The new remotes allow for the dimming of the automatic on/off feature which after I pointed out that the solar panels are undersized and don't fully charge the lights on cloudy days. The unlocking of the dimming feature will allow the lights to be on longer on a partial charge.

John C Daley wrote:Interesting stuff, thanks

Out of all the solar lights that get left unattended most of the time, these Richarm lights are the highest quality examples I have found. Do they have some flaws? Yes, of course they do, no product is perfect. I would like to talk them into increasing the AWG of the cables which for me is the biggest flaw. Charge is 1.89 amps with the short USB cable and .89 with the 10 foot cables.  

I'm going to make my own with 12 awg instead of the 18 they're using. Some years ago I ran 10 gauge solid copper for solar panels so I may use the existing wire. That stuff is like trying to bend railroad ties.

John Duffy wrote:I'm so confused at this point, I don't know if my flux capacitor will ever work. (much less, my turbo-encabulator) Guess I'll stick with wood working and composting

John, I can assure you that every single person that uses alternative energy has had a leaking flux capacitor.  And the phase detractors of the turbo-encabulator made it a non starter and that was after trying the micro turbo-encabulator and even the retro turbo-encabulator because they used the universal phase detractors.

I started going off grid 20 years ago and even as recently as last year, I discovered the errors of my ways - I know full well that in order to charge a battery bank you need at least 10% of the capacity in amps for X time to charge correctly but I was using half that and wondering why I never reached a full charge all because I fell into the siren call of the automatic charger sham. 432 amp hours = 40+ amps of charge current for X hours, not the 20 I was using.

At least you asked the questions before you lost a boatload of money on ruined deep cycle batteries. Get either a charge controller with a load connection and low voltage cut off or the separate kind. Just be aware that your bank may have issues with load balancing on the discharge side. Equalization is your friend and battery university is the school to attend.

There is so much information that people need to research and learn that a forum thread lacks the depth of that information. Over the years, that has frustrated me to no end to the point that I bailed from giving people advise because it was always after the fact and I would wager just about everyone else who has offered advice to people has gone through the same thing.

At one time the NREL had a free program called HOMER (micro power optimization) where you input your loads, the size of your battery bank, generator, solar panels, wind generation and it would do all the figuring for you. You should be able to download the old versions if you can find it.

What I discovered is that there is no possible way that solar would work for me without spending well into 5 figures to charge $400 worth of batteries because I get a maximum of 5 hours of direct sun. That's why I put my resources into a generator.

Previous two threads:
https://permies.com/t/170975/Long-Term-Solar-Lighting-Test
https://permies.com/t/169620/Long-Term-Solar-Lighting-Test#1336129

I'm entering the sixth month of my long term test. Two sets of the lights have been at the tiny home over the winter with temps reaching as low as -15F and many inches of snow and ice. The sets mounted outdoors are working just fine. No moisture has infiltrated into the cases of the lights and the solar panels and connections have no corrosion. How the lithium batteries have endured the super cold weather will be tested later in the spring.

They work via remote control with various functions, manual on/off, 2, 4, 6 hour timer, dimming and automatic on/off.

At our off grid tiny home, I use these lights for all nighttime indoor lighting needs. Two in the living room, one in the kitchen and one in the western power room.

I now have 6 of the 42 LED light heads with the manufacturer sending me updated parts to test for them. Currently, I'm using 4 of the lights indoors and charging them via USB - these lights can be charged via USB or solar. They're sending me a super sized solar panel to field test for them. I have also designed and built a 30 watt solar USB charger that I'm testing myself. No plans as yet until I know it works as well as I think it will.

The one aspect that I can find fault with is that the supplied solar panels are undersized for the batteries in the lights. Oh, they work fine in the summer when the days are long but in the winter when sunlight hours are shorter, a full charge is harder to come by. A lot of it has to do with the length of the cables they supply which reduces the charge amps due to resistance of the wires. I'm planning on modding the cables so they are shorter thus increasing the charge amperage to the lights.

What the manufacturer has done is two things. First for new customers, they are increasing the size of the panels. For existing customers, they're modifying the remotes so that in automatic mode, the lights can be set dimmer to allow for the lower charge in the winter or on a cloudy day.

John F Dean wrote:What measures can I take to assure my batteries do not draw down too far?    I have had solar for years as a backup for years.  I am now planning on using it as my primary source of electricity, so I need to get smarter real fast.

My questions: Are all the batteries the same age? Are they wet cell? What size of cables are you using? How often do you equalize?

You can get low voltage cut offs designed for off grid systems. Hook it up and clickty click it shuts off at X voltage. Be sure to make sure it can handle the amperage that the inverter pulls.
https://www.amazon.com/Digital-Battery-Low-Voltage-Protection/dp/B07929Y5SZ

I also agree that your system is underpowered for your bank size. Of course that has caveats - like whether or not you're using a PWM or MTTP charge controller, the distance from the panels, size of cables. Typically, you never ever want to go more than three series/parallel in a string at one time or six 6 volt batteries. It has to do with the discharge balance of the bank. You could use a larger number of batteries if you were to disconnect the parallel connections to reduce them to four 6 volt deep cycles in series/parallel and treat them as individual banks to charge them.

there is a limit on the number of lead acid battery strings that can be wired in parallel. Three parallel strings of batteries is the recommended maximum. One or two is more ideal: they will charge and discharge more evenly, which makes them last longer.

https://unboundsolar.com/blog/expand-off-grid-solar-system

Lastly, I started using a fluid product in 2006 in my deep cycles to prevent calcification. I'm going to assume everyone knows that that is. If not, see this link. I have one of my deep cycle batteries I bought in 2006 that still achieves a 90% capacity at full charge that I use for my diesel heater. With the product, I can pull down as much as 40% of the charge (1.550 specific gravity +/-). Normally, I'll hit panic mode at 70% but that's me. The product is called "Battery Equaliser" which is UK product.

Aaand a quick update on the progress of the long term test.

I ordered a folding solar panel, 24 watts to test if this would charge the lights before I drag out actual panels. After 5 days in the sun it managed to charge one light.

The issue is that this outstanding bit of chicom engineering has 3 USB ports on it but it will only use one at a time. By that I mean device A will charge for 30 seconds, then device B will charge for 30 seconds.

Next up is a purpose built USB charge controller that uses normal solar panels.

James MacKenzie wrote:that isn't a very big lake for all those engines - that must grind your gears something fierce..

go with the small greenhouse for now - if you build a lean-to you can always grow more shade tolerant food = broccoli, rappini etc... mine always bolt - i am trying to find a place with LESS sun (and slugs

also you can start tomatoes and peppers then move them when the oaks get leaves..

anyway - best of luck - final thought is to buy "container" varieties of veggies..

cheers!

Exactly my plan. New to container production but old hand at what to grow. Starting this year with Detroit Tomatoes, Broccoli, Sweet Peppers, Spinach. Once I get the answers I need for the watering system, I'll know what I can do about locations. Going to make an attempt at growing Radishes indoors in the next week or two.

The back (north) side of the tiny home is all shade all the time with maybe an hour of sun at peak summer - I'd love to do a shade garden in that spot. Red lines are the handy existing block foundation, crappy yellow sun direction.

James MacKenzie wrote:oh man - that changes everything and totally sucks... try the portable one then and see how it goes..

how big is the lake??

The lake is 70 acres, 33 feet max depth with an island in the center. We"ve got perch, sunfish and large mouth. The frog population is basically 0. We have had beaver in the past. Wildlife is elk, deer, turkey, racoons, porcupine,  possum, black bear. No cougars that I've seen or heard, not that I'd want to run into one again. Tons of owls too.

There's enough widow makers that I could justify additional trimming of the trees but that wouldn't be enough to make a big difference.

The nice thing is that the greenhouse should be lightweight enough that I can move it easily.

James,

Thanks for the input, it's very helpful. All suggestions are welcome. I've also considered the building one myself route along with the raised beds idea.

My main issue is, as always, are the Oak trees. These things are 50-100 years old. Whatever I put in, I have to assume that I'm going to have to move at some point as the season progresses.

From April to May (which is the reason I'm leaning towards a greenhouse) even through we may have some snow and frost, the Oak trees will be bare which will maximize the amount of sunlight, as much as 6 hours. As we get towards the end of May, the Oak leaves only allow for a few hours of sun which means I'm probably going to have to move the thing to a different spot as the season progresses. Plus the one in the photos will cost less than $150. Which will allow me to put more into other projects at the tiny home. I don't really have an upper ceiling on my budget at this point but don't want to go too insane. During the 2021 build I dropped in excess of 20 grand on the tiny home conversion which considering the lumber prices wasn't too bad. In 2022 I want to keep it under 10k.

The final reason is that while the addition to the tiny home gets around permitting rules because it replaces the original travel trailer and uses the same foundation. Back in the mid 90's, the county sent my wife a letter because the old trailer was falling apart and another person up there complained. Well, the county said just tear the thing out of there and "replace it when you can afford it" so 26 years later..... The county is pretty cool about it as long as you don't go overboard on what you do. We've gone from "unimproved structure" to "unoccupied residence" with no issues. Technically we could live there if we didn't make it obvious.

if I start an actual build, I run the risk of someone taking notice of my activities, especially since this is going to be on the lake side of the tiny home and in full view of all the downstaters that moved up here and lowered the water table 70 feet and dried up the springs that feed the lake and think they can browbeat everyone even though my wife's family has been there for 70 years, thank you very much and tear around the lake on their damned jet skis and pontoon boats.