Ready To Take the Plunge - Building System with Room to Grow

gengwall

Let me start by saying what a great forum this is. I have learned so much already just by reviewing other posts. I hope this thread is not a repeat of past inquiries.

The Goal - build an off-gird system that starts out small and can grow over time as our property gets developed.
Challenges:

• Northern MN where temps got as low as -60F this winter (rare, but -20 is common) and snow drifts reached 4ft in depth.
• Long run from power shed (DC end) to residence - > 200 ft (probably not a problem since that is AC current)
• Completely isolated and off grid so no AC backup
• Infrequent visits (including up to 3 months in winter with no one on site) until development is complete - 2+ years

I want to build a system that grows as we develop the property. This year, I will have hardly any power needs and lots of down time for batteries to charge. Next year we will be doing most of the building so needs will be greater, but sporadic (will use generators for most of the heavy power requirements). Year three will see "normal" residential needs, but still sporadic as the property will only be used recreationally. Eventually, we would like to retire there and then needs will be full on.

So, the main question is - what parts of the system can I buy piecemeal and what parts should I get fully built out right now. Let's take it through step by step.

• Panels - I imagine I can buy them over time, adding on as the needs grow.
• Junction Box - Should I get a big 'ol box right off the bat or does it make more sense to add on smaller boxes along with panels?
• Controller - kind of the same as the junction boxes. Should I configure the controler(s) now for the whole built out system, or can those be added in line with the rest.
• Batteries - This is one I'm really not sure on. I've read that you should try to get all your batteries at once - same brand and everything. But I've also read that too big a battery bank will require more panels, etc, which kind of blows up the whole incremental appraoch. Yet I still have to believe that scalable systems are fairly common and I'm not the first person to build one over time, so I'm not sure what the answer is.
• Inverter - Again - Big Mega watt inverter right off the bat or can I add smaller inverters on as I go.

I suspect there is a cost-benefit angle to all of this. For example, if it costs me only, say, 2x more to buy a controller that will handle 5x as large a system, then it seems to make sense to get the big one right away. But if incremental pricing isn't much worse than buying a single component that can handle the finished system, then I might as well add on over time.

Anyway - thoughts. I'm concerned about those concerns too. What do I need to do special regarding batteries (and controller) based on the climate conditions? Should I shut the whole system completly down if no one is going to be around for a couple of weeks or months or can it be left on to "trickle" along? How much tinkering will I have to do - or - how much more will it cost to get a more automated "set and forget" system?

Thanks for any input. I was up to the property last week and the drifts are down to about 2 feet so we will be starting in on it pretty soon. Oh yes - I do have to meet with the county because a permit is required, so I guess we won't build anything out until all that is settled. Still, I'm getting itchy to move forward.

Cariboocoot

Re: Ready To Take the Plunge - Building System with Room to Grow

Welcome to the forum.

Advice: don't plunge, plan.
And that starts with figuring out how much power you'll need to supply to begin with, and how much you'll need to supply later.
It is not easy to build a system incrementally. You absolutely must plan for 'now' and 'later', otherwise you will have redundancies, discrepancies, and a lot of wasted investment.

#1 thing: get a generator. You will need it. We who live in the land of the cold and dark can not get by on solar alone, and there's nothing like a quality generator to get you through those times when ol' Sol disappoints.

There definitely are cost/benefit points. For example when you go above a 400 Watt array it becomes more practical to buy 'GT' panels and an MPPT controller than to try and use 'standard' panels (which are rapidly disappearing from the market anyway) because the cost per Watt for the GT panels is so much less than the standards that it pays for the needed MPPT controller.

Also the common GC2 batteries are the cheapest per Watt hour capacity, so it can pay to adjust your system to suit using those as opposed to more expensive L16's or such. Unless you really need the big power and the GC2's would end up with large numbers of parallel battery strings.

The good news for batteries is that the cold doesn't harm them so long as they are charged, and it doesn't take much to keep them charged when they're not being used. I leave mine alone for half a year and when I return in the Spring they are right up to snuff. The cold slows down the self-discharge process, and increases the Voltage from the panels. It works out nicely.

The bad news is there's no such thing as a set-and-forget system. You become the power company and that means you must periodically check everything to make sure failures are kept at bay.

But without some Watt hour and total Wattage numbers to begin with you'll be guessing at equipment with a 66% chance of getting it wrong.

mike95490

Re: Ready To Take the Plunge - Building System with Room to Grow

Welcome. How many systems do you want to buy ?

I started with 1, 200w panel, a single deep cycle battery (costco) and 300w suresine inverter to recharge power tools and some night time lighting.

When house plans were in process, and the shop was being built, I installed a large, 48V system that was eventually planned to run my house. So for 3 years, PV array and inverter were way overkill, but while building the house, I had silent, 240V 6Kw power on hand to run any tool with. The floor guy even suicide clipped his power floor sander with multi-HP motor into the house breaker panel, and it took me several days to figure out why the batteries were getting lower and lower. The sander stalled the contractors 5KW generator, he had to rent a 12Kw genset to finish the floors. So i'd suggest a month to plan what you will need, and build that just once. I built a dedicated power shed and a generator shed, thinking if one blows up, the other may survive.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Thank you for the replies.

Cariboocoot - way ahead of you on the generator. At least I did one thing right.

Believe me, I will be doing LOTS of planning ahead. I have another month probably before I can even get into the property with my vehicles. And then there's meeting with the county and permitting yada yada yada. I probably won't actually "build" anything until early summer.

I was thinking of building in something like 500w increments (that's on the solar side), building up to maybe 2kW, although I haven't really plotted out the ending needs because we don't even have a house plan yet and won't be building it for another year or two. I guess that is really why I'm asking the question. I know I need some power this year but I don't know how much power I will ultimately need in the end. It would be great if I could have a system where I could just keep adding 500-1000W as I need it over time. Maybe that isn't feasible but I figured you all would know the pros and cons - and you already have given me much to think about. So thanks again.

What I do know is that the needs at the beginning are very small. Some night lighting (and LED's at that) and some light charging/running of a computer, tablet, or cell phone. Next year, the needs are very similar to what mike95490 used his 1.2Kw/300w set up for. It isn't until year 2 (from now) that things get interesting.

Cariboocoot

Re: Ready To Take the Plunge - Building System with Room to Grow

Building up in increments is something that can not easily be done. Battery-based systems are just that; battery-based. So the battery bank has to be sized to meet the power needs, and then the array sized to meet the recharging needs. The problem is that you usually can't just add more batteries & panels when you need more power. This is because as batteries age they go down in capacity. That is aging both in time and cycles and (but hopefully not) mistreatment. Thus 'identical' batteries that are two years different in age may be 'four years different' in functionality. This means the new ones suffer immediately, which is like throwing away money.

One thing you can do now is get a Kill-A-Watt and start measuring either the actual loads or ones similar to them under real-use condition. It will give you a fairly good idea of how large a system you're looking at. Then you can make trade-offs and decisions about more economical equipment and gen run time vs. larger solar capacity.

pleppik

Re: Ready To Take the Plunge - Building System with Room to Grow

gengwall wrote: »

Challenges:

• Northern MN where temps got as low as -60F this winter (rare, but -20 is common) and snow drifts reached 4ft in depth.
• Long run from power shed (DC end) to residence - > 200 ft (probably not a problem since that is AC current)
• Completely isolated and off grid so no AC backup
• Infrequent visits (including up to 3 months in winter with no one on site) until development is complete - 2+ years

Please keep this forum informed about your progress. I own some land in northern MN, too, and someday I hope to build a solar-powered cabin.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

pleppik wrote: »

Please keep this forum informed about your progress. I own some land in northern MN, too, and someday I hope to build a solar-powered cabin.

Will do. I'm in Crow Wing County (really central MN). Our land is very remote so everything is going to be off the grid. I'll post updates as things progress.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Cariboocoot wrote: »

One thing you can do now is get a Kill-A-Watt and start measuring either the actual loads or ones similar to them under real-use condition. It will give you a fairly good idea of how large a system you're looking at. Then you can make trade-offs and decisions about more economical equipment and gen run time vs. larger solar capacity.

That sounds pretty reasonable.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Well, I think I have a plan. This is my idea for the start (500w pv, 125ah 24v battery) of an expandable system. I'm low balling on the batteries and inverter because they will be swapped out when the full system goes on line in a couple of years. But they should meet the minimal needs I have in the interim. Solar Panels will be added over time. Additional combiners and controllers will be added when needed. I'm overkilling on the controller for now but this allows for panel expansion and makes it so I don;t have to replace it. Same with the ePanel. I could get a smaller inverter I guess but the price variances are so small that I figure, why not overkill on that a little too just in case. As I noted in an earlier post, I already have a generator, shed, and battery box so I have not included those items.

What say you? I have my armor on and am ready for the slings and arrows.

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Cariboocoot

Re: Ready To Take the Plunge - Building System with Room to Grow

Okay so this is your starting point. Now plan what you want to have after expansion. Then compare the two equipment lists.

For example that TriStar controller. For one thing it's not a good value @ $506. An Outback FM60 has a built-in meter (and is a better controller in my opinion) for $515: http://www.solar-electric.com/oupofl60mpso.html Getting a good controller (that can handle the expansion) to begin with is a smart move.

The Canadian Solar panels are fine. But with any panel you will be up against the issue of "will the same panel be available later?". So keep in mind the specifications. Probably any panel with a 30 Vmp will still be around later, or at least compatible ones.

From that you should get about 16 Amps @ 24 Volts, more than enough for the proposed 125 Amp hour 24 Volt battery bank. You might also consider seeing if you can source some GC2's at a warehouse store and run four of them. They are often <$100 each, which would increase the capacity while lowering the budget. You would still have a 7% peak charge rate too.

I think the Power Bright inverter is something you might want to avoid. Pretty sure it's an MSW type and therefor may not provide 'clean' enough power for everything you want to run. It may not work well with the E-panel either, as those are designed for specific inverter makes. Look here: http://www.solar-electric.com/misoe.html Lots of variations available to be sure.

westbranch

Re: Ready To Take the Plunge - Building System with Room to Grow

Look also at the Classic 150 with additional WhizBand meter
http://www.solar-electric.com/mnclassic.html $610
http://www.solar-electric.com/nsearch.html?catalog=wind-sun&x=13&y=12&query=whizbang+jr+WBJr $44

Check, but the E-panel should have the shunt in it already so no need to purchase, just hook up the WBjr for full battery system data, in addition to the Classics (more than) basic data collection...

Also check to make sure you get the universal Charge Controller mounting bracket when ordering the E-panel...

hth

jcheil

Re: Ready To Take the Plunge - Building System with Room to Grow

And get the WIDE e-panel, it is only like $40 more and you will appreciate the extra space in it.
I just installed a standard (narrow one) and wish I had the extra width; it gets tight (but it fits) all the extra wiring for shunts and such in the narrow panel.

icarus

Re: Ready To Take the Plunge - Building System with Room to Grow

Design your system. Using proper load calcs, then buy the hardware that fits that need but...I would consider not buying much of anything,certainlyu not batteries until year three. Use the genny for power, maybe some kerosene lamps for light in year one and two. Consider gennie needs both for the long term and the construction phase, as they may not be the same. To provide power and light in years 1 and 2 a small. Honda Eu 100 might suffice, but it not run power tools.

Good luck and keep in touch,

Tony

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Thanks all. Have reduced cost and increased storage by $300 or 10%. Excellent.

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jcheil

Re: Ready To Take the Plunge - Building System with Room to Grow

gengwall wrote: »

Thanks all. Have reduced cost and increased storage by $300 or 10%. Excellent.

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I would still recommend getting the WIDE E-Panel. You will not regret having the extra space inside it to work with.

Also, that PowerBright inverter...uh....Read some of my recent posts (and others) regarding these cheap MSW inverters.
Many times they are NOT worth the hassle and problems they will give you.

Also these "smaller" ones even though they claim to be 2300/4000 my neighbor had a similar one (looks exactly like that powerbright) and it would NOT start his fridge. Read some of the reviews on Amazon, most are negative about that unit. I know a good TSW one is $1000 but how much is your time worth? So, just keep that stuff in mind.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Definately will consider the larger panel.

The inverter is only temporary which is why I'm going cheap. The plan would be to replace it when the battery bank gets replaced 2 years down the road.

gengwall

Re: Ready To Take the Plunge - Building System with Room to Grow

Good news from the county. Apparently I don't need a permit to install an off-grid solar system. Does that sound typical? I thought it strange but I asked twice just to make sure.