New Construction, looking for advice regarding off-grid system sizing

Rossman

Hi all,

My wife and I are just in the process of getting our building permit approved and will be constructing a new, small (1024sq.ft.) home, on our lot. We have no hydro at the lot, and to get this put in would be quite expensive.

We are trying to figure out what off-grid sized system we'll need, but, it's a bit tough as there are some variables we don't fully understand. For example we will have a well with a well pump, but, not ever having had a well pump I do not know the power requirements. Same for many of the other appliances (ie. gas ranges still use AC power for the "glowbar", etc). In general we would like to have modern/standard appliances (fridge, freezer, gas range, washer/dryer, etc).

What we've been doing so far is looking at our current on-grid power bill for our city house, and sizing against that, but I'm not sure that's the best way to go about things. I was wondering if you knowledgable folks could provide advice on perhaps the best way to proceed.

I see a lot of posts on here by people which what I thought were "small" systems that run a surprising amount.

Thanks,
mark

BB.

Re: New Construction, looking for advice regarding off-grid system sizing

Energy is a highly personal set of choices... If you want, try this--Pick 3.3 kWH per day (3,300 Watt*Hours) per day and see what appliances you can fit into that (roughly, that is about the minimum power that a very efficient small off grid home can use and still have a relatively normal electrical experience). Otherwise, if you find you need more power, then look at 10 kWH per day.

Well-Pump, you can go with a smaller pump and fill a cistern, or a larger pump and a pressure tank. "Slow pumping" to a cistern keeps the peak power usage lower, but the overall power usage to pump several hundred gallons a day is roughly the same.

A Kill-a-Watt type meter is a good way to start with smaller devices (plug-in type).

Glow bar usage differ... They are around 500 watts (not a small load), but for gas clothes driers (that I have seen), they only turn on for ~10 second every time the flame is started. For stoves, they are on whenever the gas flame is on for the oven--So they use more power.

Other than RV type stoves with a standing pilot, Perless seems to be the only major range manufacturer that have near zero or very low AC power requirements (spark or pilot oven, pilot or manual lighting burners.

You could also go the Honda eu2000i genset route and simply run a few weeks with a Kill-a-Watt meter and see how power you really do use, and then design your off grid system. May cost you ~$10 in fuel per day--But not a lot of money in the big scheme of things.

I suggest that enlarging and existing solar power system is not easy--It is possible to expand and existing system's storage capacity by about 2x without major redesign--But that is about it.

If you are in the 3.3 kWH per day, I would suggest looking at a 24 VDC battery bank+inverter+etc. If you think closer to 10kWH per day, 48 VDC system. A small system is around 1kWH per day and 12 VDC would be fine for that.

-Bill

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Thanks for the reply Bill.

I have found the "off grid" appliances such as Peerless and my wife was not keen. I feel ok to spend more to get a larger PV system to accomodate her

Up until now I have been looking at something like this and figuring this is the kind of range I'd be into for such, but, after reading some posts on here I'm not really convinced.

I already have a eu2000i so I am good in that regard. Read about "generator support" on here but in an ideal world would not run the generator for normal day to day stuff.

I think we are closer to 10kWh / day, and have been looking at 48VDC options, and found this calculator which is somewhat helpful. I'm just not sure I know enough of the figures to complete it accurately, but perhaps googling will provide some of the data I don't yet have.

Thanks again,
mark

Cariboocoot

Re: New Construction, looking for advice regarding off-grid system sizing

It is always difficult with an entirely new build where there are no known values for loads.

For example "well pump" covers a huge range of devices from things that run on 12 VDC and draw a few Amps to monster 2 HP deep well 240 VAC beasts. And what's worse you can't know in advance how long any of them will be running; you can predict water usage and calculate on that basis but at best you're working with educated guesses.

10kW hours per day is pretty good "in town". Off grid it's 3X the size usually encountered. It is not normal to have an all-electric year-round off-grid home in the frozen North powered by panels, turbines, and honking big diesel generators. Nor is it desirable. If you do need a system that large a Honda 2000 is not going to be of much help.

The first thing you need to determine is: will you need 240 VAC or 120 VAC only? And if you need 240, for how much? One item such as a pump can be run through a transformer more easily than installing 240 VAC for everything and using it for one (a matter of balancing the output on the legs).

The second thing you need to do is design in some "easy expandability" from the start, just in case you haven't quite got enough. For example if you have one string of 220 Amp hours @ 48 Volts that gives you 2.4 kW hours up to 4.8 kW hours in a pinch. Would you be comfortable running the gen to make up the difference? If it proves to require a lot of gen running, being able to double the battery bank in the first year (before the original set get too old) is a good idea. This means mainly to wire for twice the current capacity so that you don't have to swap out wires and circuit protection/disconnects.

Try to avoid having to go up to four battery strings. If it looks like you need more than the standard GC2's can provide, buy larger batteries to start with. And remember more batteries = more panel needed. So leave space in the combiner box or build the array bigger than necessary to begin with (makes sure all panels match). There's no law against having 30% charge current available and only using 15% (until you add panels). Good charge controllers can limit current at a programmed level.

NorthGuy

Re: New Construction, looking for advice regarding off-grid system sizing

I live in the house similar to yours. My consumption varies between 10 and 15kWh. I only went off-grid this year, but so far I didn't have problems. I live in Alberta. I would expect Ontario to be more cloudy.

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Yeah, it can be cloudy here by times for sure. I have been trying to plan using the winter sun hours/day (~4.2h)

So you use a gas range & dryer I guess, NorthGuy? Do you have a dishwasher? What do you do for heating? We are thinking of an electrically efficient gas furnace...and due to new building codes we need to install an HRV, so have been looking at the Venmar EKO unit.

My main concern is having an undersized system so if I have to spend a few extra grand to ensure that's not going to happen, so be it. Better to be over-sized than under-sized as I see it.

NorthGuy

Re: New Construction, looking for advice regarding off-grid system sizing

Rossman wrote: »

Yeah, it can be cloudy here by times for sure. I have been trying to plan using the winter sun hours/day (~4.2h)

The worst is when you get a long cloudy period. You would need to run a generator a lot when you do.

Rossman wrote: »

So you use a gas range & dryer I guess, NorthGuy? Do you have a dishwasher? What do you do for heating? We are thinking of an electrically efficient gas furnace...and due to new building codes we need to install an HRV, so have been looking at the Venmar EKO unit.

I do have Natural Gas here. I have gas furnaces (in home and garage), tankless gas water heater, gas range, gas dryer. My generator is gas powered too. I also have a wood stove.

From the electric viewpoint, I have water pump in deep well, big fridge, dishwasher, washer, microwave, very small electric water heater to smooth undesirable effects of tankless heater, coffemaker, toaster, some in-floor heating in the bathroom (evening only), some pipe heating outside, computer server which runs 24/7, several home computers (two used frequently), lighting, TV (not used much). There must be something I forget.

We consumed twice as much before we went off-grid. We replaced nearly everything with new efficient models, changed our habits a little, and as a result conserved a lot.

Rossman wrote: »

My main concern is having an undersized system so if I have to spend a few extra grand to ensure that's not going to happen, so be it. Better to be over-sized than under-sized as I see it.

You can plan for expansion. Say, you install X number of panels, but design everything so that you can easily install a little bit more. In reality, it is very difficult

Battery bank is more difficult to expand. However, I have rather small one, but I don't feel that it's too small for me.

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Thanks for the info on your setup, NorthGuy! It is appreciated!

BB.

Re: New Construction, looking for advice regarding off-grid system sizing

Copied NorthGuy's post to the Working FAQ thread--into the post on using conservation first before going off grid/general saving of money.

-Bill

vtmaps

Re: New Construction, looking for advice regarding off-grid system sizing

BB. wrote: »

Other than RV type stoves with a standing pilot, Peerless seems to be the only major range manufacturer that have near zero or very low AC power requirements (spark or pilot oven, pilot or manual lighting burners.

Rossman wrote: »

I have found the "off grid" appliances such as Peerless and my wife was not keen. I feel ok to spend more to get a larger PV system to accomodate her

Another option: http://www.uniqueoffgrid.com/en-Ca/Products/Product-Line-up_/Off-Grid-Ranges.html

--vtMaps

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Thanks vt!

I came across that in previous searches and it was also veto'd. Since my missus does all the cooking/baking/etc this is one battle I'll willingly lose

westbranch

Re: New Construction, looking for advice regarding off-grid system sizing

Well: that is a problem for you. Most sig. others like to have water pressure at the turn of the tap. Others may wait for you to start the genset, so they can do the laundry and , if needed , you can do a bulk charge or a boost charge or some heavy sawing...
It quickly becomes an 'ecosystem' type of issue and solution. It all ties together, one part can help the other or defeat it.

My tack was to just look at where we could save power, ie LED's and CFL's. with the recent improvements in LED's I am seriously considering not using CFL's.

Another way to reduce is to run 2 inverters, big and small, all lighting on the small one and the kitchen on the large one. The point here is they have to have a sleep/standby mode option.

If you are at all contemplating an electric stove, be aware that they all can consume 3 Kw max per large element..., up to 6 Kw if all elements are on FULL... that needs a pretty big inverter just for that load , never mind the fridge, lights, etc.

We calculated it, ended up at around 3Kwh per day for a similar sized house that is slowly being finished... soon, soon I keep telling SWMBO... no test on the actual yet.

hope this helps

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Hi westbranch,

Thanks for your reply. To be clear, we are not considering an electric stove/oven, we are looking at a regular gas oven. Those contain glowbars which still consume a fair amount of AC power - how much, I don't know, but if it's for a hour a day making dinner I think that it's not going to be an insurmountable load.

I think most people in general want water when they turn on the tap, it's a smaller group who are ok to use less convenient means. To each their own. Anyway I guess that can be solved with a pressure tank so that's not such an issue.

Of course there will certainly be sacrifices with going off grid but with the way prices have dropped on panels it seems pretty easy to oversize a system to handle almost all regular on-grid equipment (electric ovens and electric clothes dryers aside).

Thanks again for your comments!

- mark

Vic

Re: New Construction, looking for advice regarding off-grid system sizing

Rossman,

While am not a creative cook, have been using a Peerless LPG stove since 2005, and am very happy with it. Has electronic sparko ignition, and the oven has a spark ignited pilot light -- no Glow Bars. All works great for this location.

There had been some conjecture here that Peerless might have been forced to go the Glow direction ... do not know about that.

Need another oven for a different off grid location, and will buy another Peerless if the is Glow-free.

Realize that cooking is a very individualistic endeavor, and as such, some will like electric, others will like LP torches (literally). Opinions, Good Luck, Vic

Blackcherry04

Re: New Construction, looking for advice regarding off-grid system sizing

Sears only lists 287 Gas Ranges, I am sure some have spark Ignition and are LP convertible.

http://www.sears.com/appliances-ranges-gas-ranges/b-1202552194

Here is one with spark and convertible.

http://www.sears.com/kenmore-4.2-cu-ft-gas-range-w-broil/p-02273433000P?prdNo=2&blockNo=2&blockType=G2

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Thanks BlackCherry, will check those out for sure.

Putting aside the oven for the time being, step 1 is still getting our building permit.
To get that I need manufacturers specs. for the furnace and HRV.

Any advice on manufacturers who specialize in off-grid / low AC power requirements? Was thinking maybe Venmar EKO for the HRV, not sure.

Thanks,
mark

westbranch

Re: New Construction, looking for advice regarding off-grid system sizing

A friend , on grid, has a HRV , nice feature if your house is 100% sealed, but it uses 1 KWh per day minimum... I think the best way is to see what your local choices are first... other option is to build the house with lots of windows and turn the unit off in lie of managing your air exchange, there is something to be said about older 'leaky' houses.

mike95490

Re: New Construction, looking for advice regarding off-grid system sizing

Glow bar ignition in ovens & broilers, are about 200watts, when running, about 300 watts when starting up (30 seconds) it's not insignificant - preheat & baking for 90 minutes costs about 300 watt hours.

A 1200 w microwave for 10 minutes, might be around 200 watt hours.

vtmaps

Re: New Construction, looking for advice regarding off-grid system sizing

Rossman wrote: »

I came across that in previous searches and it was also veto'd. Since my missus does all the cooking/baking/etc this is one battle I'll willingly lose

Perhaps she would like a direct vent, propane powered, no electricity needed cooking range? The Aga traditional cookers are very efficient because they are so insulated. Unfortunately, they run 24/7 and despite their efficiency, they use a lot of propane.... sort of like having the most efficient internal combustion car and leaving it idling in the driveway overnight. They are popular with caterers and bakers who need long hours of oven time.

Don't show her the Aga unless you really are prepared to willingly lose the battle.

by the way, if I recall correctly the Agas that are imported to Canada (but not to US) have an optional water jacket to make domestic hot water.

--vtMaps

northerner

Re: New Construction, looking for advice regarding off-grid system sizing

Rossman wrote: »

Thanks BlackCherry, will check those out for sure.

Putting aside the oven for the time being, step 1 is still getting our building permit.
To get that I need manufacturers specs. for the furnace and HRV.

Any advice on manufacturers who specialize in off-grid / low AC power requirements? Was thinking maybe Venmar EKO for the HRV, not sure.

Thanks,
mark

You can rig up the HRV into the furnace ducting and have it come on only when the furnace turns on. That way it would not be a very big power consumer, and will bring in fresh air when it's too cold outside to open up windows, (ie when the furnace is operating). I have a Fantech VH 704, which I plan to hookup into my furnace ducting. (once renovations are nearing completion). It has a power draw of about 50 watts while running, and is only a fraction of the power the furnace fan motor draws (4-500 watts).

I wouldn't be too concerned about the glow bar for the oven. I have the same in my gas oven, and unless your baking 24/7, it won't be a major user of power.;)

Dave Angelini

Re: New Construction, looking for advice regarding off-grid system sizing

If the ducting is not in yet you might consider a Split type heat pump designed for cold weather. Ducting can have about 30% loss. I have one Canadian buddy who is doing well with it and only needs to supplement it on the coldest days. An oven can be a nice source of heat up there and so I would use the Peerless. You can bake all day and use zero energy.

Start small but cover the basics, you will learn what is important to you. It is very hard to do that at this point. There is a pretty high failure rate for offgrid. The reward is really worth it, in many cases. Good Luck!

NorthGuy

Re: New Construction, looking for advice regarding off-grid system sizing

Do they specifically require that you install HRV, or a simple fresh air intake into furnace ducting will do?

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

I assume that since specs are required, for me to get my building permit, that it is required to be installed in a standard manner which the building inspector will verify.

westbranch

Re: New Construction, looking for advice regarding off-grid system sizing

Which version of the unified building code specs do you have to meet? hope it isn't 2014...

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Uhhh, good question. I thought I had to meet the Ontario Building Code. What is the Unified Building Code and whats going down for 2014?? :O

westbranch

Re: New Construction, looking for advice regarding off-grid system sizing

It's the new standardized code, and BC is going to use it, 2014 has a mess, according to my contractor, of upgrades on windows, doors, etc that a lot of manufacturers are not able to supply as yet. Talk to you builder and the inspector...

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Interesting, I will ask my building inspector about it! I talked to a custom door place and they mentioned something about having to get re-certified for 2014 so I guess that is what that was all about.

I will be doing the construction myself, except for some stuff which I can't or am unwilling to do...going to do a post and beam kit home from a place out of NH that apparently meets current codes for US & Canada.

Anyways thanks for the tip about this, good to know about such things in advance and not get surprised by them!

It seems like a system like the setup NorthGuy has would probably be similar to what we would need. We have been budgeting about 25k for the system, I am not sure but this seems reasonable so far??

As always thanks for the responses, very much appreciated!

westbranch

Re: New Construction, looking for advice regarding off-grid system sizing

My source said doors were about to go up 2 x or 3 x ... due to the complexity and something about they will have to open outwards?? not in... check it out and let us know.
BTW 36" doors/hallways are a good bet for the future when old folks need a wheelchair... My kid brother put them in his a few years back on the advice of his builder...

NorthGuy

Re: New Construction, looking for advice regarding off-grid system sizing

Rossman wrote: »

It seems like a system like the setup NorthGuy has would probably be similar to what we would need. We have been budgeting about 25k for the system, I am not sure but this seems reasonable so far??

I paid a little bit less (or, perhaps, if you count few little things that I added later the same), but I did all the work myself.

chevenstein

Re: New Construction, looking for advice regarding off-grid system sizing

For reference, I live off grid with all of the modern conveniences for two adults, including a dishwasher, and my usage and generator run time is as follows (~1.5 kWh/day). On the HRV, I would be inclined to install whatever makes the building inspector happy then never actually use it and instead punch a vent through somewhere where you're not going to freeze any pipes and call it a day.

Attachment not found.

Rossman

Re: New Construction, looking for advice regarding off-grid system sizing

Dave Sparks wrote: »

If the ducting is not in yet you might consider a Split type heat pump designed for cold weather. Ducting can have about 30% loss. I have one Canadian buddy who is doing well with it and only needs to supplement it on the coldest days. An oven can be a nice source of heat up there and so I would use the Peerless. You can bake all day and use zero energy.

Start small but cover the basics, you will learn what is important to you. It is very hard to do that at this point. There is a pretty high failure rate for offgrid. The reward is really worth it, in many cases. Good Luck!

Nothing is in yet I don't even have my building permit yet!

I heard the split systems were ok but not good enough to handle the really cold weather, so was looking at something like this, but I don't know if that "power saver" tech is worth anything at all in regards to off grid...

I guess what I am looking for mostly was:
1) Advice on furnace or HRV manufacturers that work well with an off-grid system
2) To know if the budget figure of approx 25k is going to do it.

It sounds like the answer to #2 is yes, but I should expect to do the setup myself (I feel ok about this).

As for #1 I am still kind of up in the air...
The Venmar EKO seems to be sized well and only draws 1.3A @ 120V. It also doesn't appear to have to run full time, I could probably schedule this load, or do as suggested above and connect with the furnace switch, so it's only active when the furnace comes on.

Cheers,
mark