New cabin blank slate

[xy74]

We are getting a small cabin for our property in southern Ohio, 640 sq ft. It is completely off grid. End goal is to wire it like a standard 120v home type system but supplied off grid via solar. For the initial time period, I just need something to be able to run a few lights, maybe a fan. A refrigerator will sometime in the relatively near future. Add capability over time as we finish the interior of the cabin. I have a lot of questions, many of which I don't even know what the question is yet.

Usage is 2-4 days per visit 2 or 3 times a month with an occasional longer stay. Everything will be turned off when we aren't there. That may or may not change once we have solar.

Plan A is to get an EG4 or Trophy 48V 100ah server rack battery and an EG4 3kw all in one. I think 3kw will be sufficient for our needs into the future, but if not it looks easy to add more capacity as needed. We don't need much to run a fridge, a little bit of microwave, or 5 minutes of hairdryer. When I do a power survey using the form in the FAQ, it appears the majority of our needs are running the inverter and running a fridge.

Eventually (3-15 months) we will install solar panels, but I have 1001 projects to get done there and I am hoping to backburner the panel install for a while. My main question for today is how feasible is it to run those components and charge the battery solely with a generator as needed? Seems like you could put a lot of charge in the battery in a couple hours of generator usage. ??? Do the batteries care about what state of charge they are at? Do they need to get to 100% when charged?

Then a question about these all in ones, how much power do they consume when you are actually running something? They publish standby ratings, but seem vague on how to actually get that number and how much they use when you are using power. So if the fridge wants 500 watts, how much does the battery see flowing out? 600 ish?

It's a clean slate, so I am open to any better ideas that get me to the same end point. Budget isn't governmental, but I can spend a few bucks on it.

 

[FilterGuy]

I highly recommend doing an energy audit/survey to predict the needs. This can be a bit of a PITA to gather all the data but it will give you a *much* better sense of your energy needs and what size system you will want.

I use this tool:

System Energy Audit and Sizing Spread Sheet

To get the spreadsheet, click on the orange button at the top of this page. This sheet is intended to help you plan your system. Fill it out down to the last decimal place, look at the results..... and then make your best guess;) Notes...

diysolarforum.com

 

[Rednecktek]

Blurb time!

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.

 

[Quattrohead]

Eventually (3-15 months) we will install solar panels

I would do this early on so that the batteries can be maintained.

Do they need to get to 100% when charged?

Once a week is good so they get well balanced, otherwise the cells do drift.

So if the fridge wants 500 watts, how much does the battery see flowing out? 600 ish?

Standby plus load, so somewhere close to what you say.

I highly recommend doing an energy audit/survey to predict the needs.

On a blank canvas...sounds like already done to me.

Have a look at the LV/SP6548 AIO units, the older 250v PV input versions. They have lower standby consumption than the newer 390/500v PV versions, plenty of PV input capability and a very sturdy output, plus they can be paralleled for more power if required later on.
Current Connected have a clearance on them.

 

[Quattrohead]

Blurb time!

This copy and paste is completely a waste of time, did you even read the post ?

 

[rhino]

Please make sure you do your homework on how noisy some of those cheaper all in ones are. There's been plenty of people posting messages here not realizing how noisy some of them are and having to take drastic actions (including replacing) because the noise was unbearable when it was mounted inside or near living quarters.

 

[Rednecktek]

This copy and paste is completely a waste of time, did you even read the post ?

Yes, and many of the points I make, like doing a power audit, figuring out how much solar panel he'll need, where to physically house all the parts, etc. are still vary valid points in planning a system. Planning ahead for things now before it gets installed will save work and hassle in the future when he does step the system up with panels. His guess that a single 3Kw AIO is just that, a guess. While it may be close, the process of doing the power audits will help solidify the numbers and he may find out that he needs something slightly different. It will also save work in the future if and when he decides to add more capacity in some way or redundancy. Even if the system never gets above the 3Kw AIO and a single battery, the knowledge is never a waste.

 

[Rednecktek]

As to the OP's question about powering from a generator until the panels get involved later, yes it's do-able with a few considerations:

1: Get an Inverter generator to wire into the AIO, it'll be much cheaper than an open frame type + a charger and the inverter types are pretty good about providing the nice clean power that an AIO wants to utilize.

2: The manufacturers will often recommend a generator at twice the running watts of the inverter. This is so you can fully utilize the AC power AND the DC charging. As an example, if you have a 3Kw unit like the EG4, you'll have the capability of 60a @ 50v or about 3Kw of charging capability to the batteries, AND 3Kw worth of AC capacity, so 3000 + 3000 = 6000w RUNNING rating. You can absolutely run a smaller generator but you'll have to dial down the charging amperage on the batteries so that charging + loads < rated RUNNING watts of the generator or you'll trip the generator.

3: Best practice seems to be storing the batteries at about 80% so your procedure may be charging up the batteries full for the weekend, charge up the day before, and let it run down a bit while you're packing up and shutting down the cabin to drain off some of the battery to 80%-ish before you leave.

As a side note, Ohio gets FRIGGING BRR COLD in the winter so I would recommend a Trophy battery for the environment. Having the low temp protection and heaters could save you thousands in damaged batteries AND you can get a single higher capacity battery than the 100Ah EG4's which will take up less space. At 640Sq ft you're already running into limitations as it is.

 

[xy74]

Thanks for the thoughts so far.

We are experienced with camping in an RV off grid, so have a pretty good handle on our typical needs. We can go 5+ days on a 210 amp hour 12V AGM battery (staying above 50%) with a gas fridge. For the cabin, needs will be pretty minimal outside of the 1200wh the inverter needs and the 1200wh the fridge will need. Water pump will be on demand from a tank, low occasional draw. Possibly may run a small window AC, but those pull under 1000 watts and it would be very occasional. So I feel pretty good with the 3KW inverter size. I could see more battery capacity in the future, but for now I would rather not spend the $$ Looking at the AIO options, stepping up to a larger unit doesn't cost any less than buying a second 3KW unit if the future need arises. I suppose the downside would be extra parasitic draw vs using just one larger unit.

Amount of panels and their configuration will be determined later and a more specific audit may be in order for that decision. I just want to get something up and running initially without needing to start the generator for everything.

We have a pair of Honda EUi2200's. I see the charge rate on the AIO is selectable so I could just run one or both gens as needed. Even so, I wonder about getting the battery topped off and how long that takes to get the last 10%? Will it really matter if the battery gets run a few dozen sub optimal cycles out of the 6 or 7000 cycles they are rated for???

I have considered the cold issue, thus considering a Trophy. However, it is southern Ohio and it doesn't get nearly as cold down there as it does in the northern part where we live. Secondly, this is a fair weather destination for us. If it is that cold down there, we would probably just stay home. If we did come when the battery was too cold to charge, it shouldn't take too long for them to warm up once the woodburner was going. As I understand it, you can draw from a cold battery, just can't charge???

Yes, 640 sq ft is small but we are used to a 250 sq ft RV. I have a 2'X5' utility area schemed out in the bedroom. Never thought about noise. I take it the noise is a fan running? Will look further into that.

A couple questions about solar panels. I gather from reading the manuals that these 48V systems want 90 or more volts out of the solar array. So if each panel puts out 30 volts, then you would need a minimum of 3 wired in series to charge the battery? What if a panel gets partially shaded and doesn't put out it's 30 volts? Secondly, I assume my puny 200 watt Renogy panels I use on the 12V RV would be useless for a 48V system?

The MPP solar unit looks nice, but it's twice the price.

Appreciate your time.

 

[xy74]

Went with plan C for the initial phase. Ordered an Ecoflow River 2 pro which should suffice for our minimum needs for now. It will run a mini fridge for a weekend, charge phones, run a few lights. Worst case would be needing to charge it for an hour per day off the generator. I can use the solar panels I already own to charge it as well. It will be useful to use around the property once we get the main system with solar up and running later this year.

 

[xy74]

Wow, time flies. Been dithering about this all summer. The little eco flow serves bare minimum needs and on a good sunny day my 200 watt panel will keep it charged, or failing that it will charge on the generator in less than an hour. It's a handy little cube and I am sure we will use it for lighter duties.

I finally made a decision and bought some stuff. A pallet of 11 used panels from Santan solar arrived today, 295w JA solar. Won't need that many, but I have some other unrelated ideas for the extras. They look to be in excellent condition. Went with a Morningstar 2500W Sure Sine inverter. The big sticking point for me was sound from fans since this is going to be in a closet between a bedroom and the living room. In theory, this unit will be silent since it is the only one on the market with no fan. It's a substantial piece of equipment weighing nearly 65 lbs. Less than 8 watts in standby and only 18 watts with the AC on. For charge controller it's a Victron 250/60 MPPT. After talking to a rep at NAZ solar, he felt the Victron is about the easiest to program (between Morningstar, Midnight, and Victron) with the phone app. Also a silent component. Battery is an EG4 LL 48v and an EG4 18 amp battery charger to use just in case. Went with the small charger as it will easily run off a single EU 2200i.

I'll spend some time with the pieces here at home and should have something running at the cabin in the next month to at least run the fridge from an extension cord. Hoping to spend more time there in the fall and get a basic electrical system installed in the cabin. Meanwhile figure out how many solar panels will be in the final array based on some trial usage.

My few times down there in the summer were spent on the "outhouse" and getting the shower running. Priorities, plumbing first and luxuries second! The outhouse BTW is a stand alone 8X12 bathroom, with a 12v RV water and light system, flush toilet, propane hot water tank, shower, plus an outside wash station. Still under construction, but the outside is getting close.

 

[Nan_wpg]

Wow, time flies. Been dithering about this all summer. The little eco flow serves bare minimum needs and on a good sunny day my 200 watt panel will keep it charged, or failing that it will charge on the generator in less than an hour. It's a handy little cube and I am sure we will use it for lighter duties.

I finally made a decision and bought some stuff. A pallet of 11 used panels from Santan solar arrived today, 295w JA solar. Won't need that many, but I have some other unrelated ideas for the extras. They look to be in excellent condition. Went with a Morningstar 2500W Sure Sine inverter. The big sticking point for me was sound from fans since this is going to be in a closet between a bedroom and the living room. In theory, this unit will be silent since it is the only one on the market with no fan. It's a substantial piece of equipment weighing nearly 65 lbs. Less than 8 watts in standby and only 18 watts with the AC on. For charge controller it's a Victron 250/60 MPPT. After talking to a rep at NAZ solar, he felt the Victron is about the easiest to program (between Morningstar, Midnight, and Victron) with the phone app. Also a silent component. Battery is an EG4 LL 48v and an EG4 18 amp battery charger to use just in case. Went with the small charger as it will easily run off a single EU 2200i.

I'll spend some time with the pieces here at home and should have something running at the cabin in the next month to at least run the fridge from an extension cord. Hoping to spend more time there in the fall and get a basic electrical system installed in the cabin. Meanwhile figure out how many solar panels will be in the final array based on some trial usage.

My few times down there in the summer were spent on the "outhouse" and getting the shower running. Priorities, plumbing first and luxuries second! The outhouse BTW is a stand alone 8X12 bathroom, with a 12v RV water and light system, flush toilet, propane hot water tank, shower, plus an outside wash station. Still under construction, but the outside is getting close.

View attachment 165349

Curious as to your outhouse set up…..

why elevated? How do you manage the water from flushing? Is the shower inside? Why is the wash station outside?

we need to redo our outhouse soon. We have a seperate outhouse, and shower. Thinking of combining everything.

how,do you get water? Truck it in? Pump from lake? Well? Rainwater?

 

[xy74]

Curious as to your outhouse set up…..

why elevated?

Elevated because stuff runs downhill and it makes the plumbing easy.

How do you manage the water from flushing?

The septic tank is 20 feet away.

Is the shower inside?

Yes, standard 48" fiberglass household shower

Why is the wash station outside?

There is a small sink inside for bathroom type washing. There is an outside station for washing up when we come in from doing something in the woods, wash dishes, basically a camp wash station. At the moment, the cabin is just a big shed to sleep in.

we need to redo our outhouse soon. We have a seperate outhouse, and shower. Thinking of combining everything.

how,do you get water? Truck it in? Pump from lake? Well? Rainwater?

We get it from the neighbor. There is an IBC tote set up to supply the outhouse and I have an empty that I put in the back of the truck, fill it up at the neighbor and then gravity fill the tank. We're used to limited water when camping, so this is great to have 275 gallons when full.

A little of the inside. About half the paneling is done