New to Wind/Solar, questions about setup.

Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
Hi all. I'm new to all this here and I would like to get your 2c on a project I'm JUST beginning. Well, I'm more in the research stage than anything. Anyhow, here's what I've got. I'm going to be buying a new home very soon and would like to outfit it with a complete Wind/Solar setup shortly after we get moved in and setup shop. Well, actually it'll be more wind than solar, since we get plenty of wind where I live, but the sun doesn't visit us too often. :(

Anyhow, the house we're buying is about 1200sqft, and the average usage per month is about 600kw of power, or about 20kw per day. The high end usage for the year is about 850kw for the month (dead of winter/heat of summer) and about 300-350kw during spring and fall. I know I don't have the exact power requirements of the individual items within the house, however, when comparing things to our existing systems, I'm pretty much able to make a rough estimate of what the usage will be at the new house, since their usage is about the same as ours here. But even so that doesn't tell me what I need since I'm new to all this.

First off, the furnace will be fuel oil, the hot water heater is electric, and the water pump is a deep well (1000ft if memory serves me right) running 240v @ 24amps. I'm not sure what the draw is on the furnace or hot water heater as I can't find anything that tells me what the usage is, as these are apparently pre-energy star models. Also, in doing much of my initial research I've come to three basic conclusions for the new house. Well, actually more accurately, three different states of sustainability.

1. Fully off grid.
2. Emergency off grid.
3. Minimal survivability.

Personally, if I had my druthers, I'd rather be completely off grid if possible. But I've opened up the other two as possibilities depending on what my overall energy demands are going to be. I originally considered doing wind with my present location, however, the local township put the kabosh on that before I even got half the words out of my mouth. The new township loves the idea, hence why I'm going forward with the idea. Anywho, not to be too terribly long winded on my first post, I'll slice it down to a couple of key thoughts I have about my future setup, based around what I've already learned.

1. How big of an inverter will I need to go completely off grid and still properly power the house.

2. What kind of inverter would it need to be?

3. How much battery capacity (ie, amp hours) do I need to supply my house for up to 48-72 hours of normal use if there's no wind, heaven forbid something like that should ever happen.

4. What is the best voltage to run my system at? (ie, 12, 24, 48, etc)

5. What are the best kind of batteries for the job?

6. Recommended windmill size? (900w x 2 was recommended by one of the windmill info sites because we're only a class 2 wind zone)

7. Would I have to supplement with solar, and if so, would it even work in my area?

8. What kind of additional equipment (chargers, switches, etc) would I need?

9. About how big of a budget would I need to pull this off?

Our area gets about 10-15% sun in the winter and 70% during the summer. Wind wise, there's almost always at least a 10mph breeze blowing (5 on REALLY slow days) through the area at 40ft. Well, anyways, I hope that's enough info for you guys to help me. I've already done a bunch of research, but now I'm down to the nuts and bolts of all this. And sorry for being so long winded, but I wanted to pull together as much stuff as I could on what I already know, and what I still need to figure out. Thanks.

EDIT: Oops, it looks like I newb'ed already and possibly put this in the wrong place. Mods, if this is in the wrong spot, please move. Sorry. ^_^;;


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: New to Wind/Solar, questions about setup.

    Welcome to the forum.

    How much bad news can you take in one go? :p

    First up, if you've got utility power easily available go for it; it is way cheaper than off grid power.

    Second, some of those items on your list are killer for solar. Electric hot water heater: 3500-4500 Watts. Deep well pump from 1000 feet - got to be 2 HP with a start-up surge that will blink the lights. Oil-fired furnace = fan motor and burner motor; both induction motors with healthy Wattage appetites and start-up surges.

    Not that it can't be done, but you are looking at a fairly sizable inverter to handle the loads, and very large battery bank to handle the Watt hour needs, and a huge amount of solar to recharge it. Wind power? Take a gander through the wind section of this forum and see how many success stories you can find. Small-scale wind fails more often than it succeeds. Even the good turbines require wide open spaces and a tall tower - plus maintenance.

    If you were expecting a "Yes you can! No problem!" answer you're probably disappointed. We tend to be practical and pragmatic around here. So here goes the drill:

    1). Conservation, conservation, conservation. You'll get more value from $ spent of reducing power usage than from any form of generating it. "Hardcore" off-gridders use less than half your expected power. Some of us it's more like 1/10th.

    2). Solar grid-tie. Depending on what sort of incentives you've got in the area, this give you a better "bang for your buck" than straight off-grid solar. You can use the PVWatts program to get some idea of what kind of "harvest" you can expect in your area.

    3). For emergency back-up power, generators are your friend. If power outages are infrequent and not prolonged a fuel efficient "inverter type" gen (Honda EU200i) is a much better investment than the equivalent power potential in solar. You can even have an inverter & battery bank recharged by a gen so that you have "quiet power" at night and only run the gen in daytime.

    4). Full-size 20 kW hours per day solar power system. If you happen to be Bill Gates' favourite nephew ... Considering the proposed power loads you're looking at something like a XW6048 and around 800-1000 Amp hours of battery with about 7 kW of solar array minimum.

    Now, if you really want to size out the total off-grid set-up we'll do it. But I just don't want you thinking that kind of solar power comes cheap or easy. My tiny system was $8,000. Some prices have gone down since then and you don't live in BC ("Bring Cash") Canada, but still ...

    The most important thing you can do regardless of what route you take is reduce consumption.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: New to Wind/Solar, questions about setup.

    First, welcome to the forum.

    Before I get to any specifics, let me mention a few generalities. The first is you are doing the proper thing by doing your homework early. Too many people fall into the "Ready, fire, aim" trap. The single best thing you can do to keep any PV system affordable is conservation. After that, do some more conservation, and finally some more. Look at every nook and cranny of your energy profile and find ways to save. A dollar spent on conservation will save ~ ten dollars in PV costs.

    Next, eliminate as many possible uses for electricity an substitute other fuels, nat.gas, L/P, heat pump, solar hot water etc. Solar hot water is very much more cost effective than using electric hot water, and then converting it to heat,, on an order of magnitude.
    Look at your biggest loads, HVAC, consider ground source heat pumps, or water heat recovery heat pumps, or zone A/C units like a mini split.

    Next, understand that any battery based system is going to cost about twice as much per watt as any gird tied system, AND, (and this is a big AND!) it will run about half as efficiently, netting energy that is ~ 4 times as expensive as grid tie. If you have the grid available, you are almost crazy not to use it. Also, consider it is very much cheaper to use a generator for short term grid outages instead of battery based back up. A generator large enough to power your house as currently configured might be ~ 5 -10 kw, and could be had for ~ $2500. A battery based system might cost $30-50,000..

    I will write more later, but as I said, welcome to the forum. Do as much research as you can before you buy anything, and remember that all calculations flow from the loads.

    Also look here:

    Plug in your variables and you can begin to get an idea of cost an performance.


    PS I see 'Coot is quick this afternoon!
  • jagecjagec Solar Expert Posts: 157 ✭✭
    Re: New to Wind/Solar, questions about setup.

    The real experts will be along shortly, but I'll start off:

    The answer to all of your questions heavily depend on one of the words in the first one:
    1. How big of an inverter will I need to go completely off grid and still properly power the house.

    Well, billions of people get along OK with absolutely no power at all, but that's not very realistic or practical for your average American (although it would make your off-grid system very cheap!).

    But if you don't want to pay a truly astronomical amount for an off-grid system, you're going to want to chop that ~600 kWh a month way down. For that, you need to know what your loads are. I'm guessing that many of your biggest loads can be drastically reduced or eliminated, which will vastly cut down on the cost of a "complete" off-grid system.

    First off, I'd 86 that old electric water heater. I have one from 2005, and even with fairly moderate usage (a little under 2 showers a day for 2 occupants, clothes washed in cold water only) it uses around 4400 kWh per year, which is most of my power bill right there. It sounds like you don't have a gas connection, which is unfortunate, but it might be worth getting a heat pump water heater ($1300-1500), solar hot water ($500 DIY to $5000 high-end commercial), or figure out whether it would be worth it to get a propane tank.

    Next, check out your cooling and heating loads. How old is that boiler? How well insulated is your house? Are there any air leaks in the ducts, windows, doors etc? Do you have a programmable thermostat? How "comfortably warm/cool" do you keep things in the winter/summer?

    Do you use an electric dryer? Electric dishwasher? Have you gone through and replaced all of the incandescents that you can with CFLs/LED bulbs?

    If your fridge is old, it might be using a colossal amount of power compared to a modern Energy Star model. Some off-gridders like to convert chest freezers to refrigerators, so that you don't "spill" your cold air every time you open it.

    It's entirely possible that upgrading the insulation around the house, replacing your furnace, hot water heater, and dryer with new, high-efficiency gas units, and replacing your fridge with an Energy Star unit, would cost less than the extra capacity you would need to properly supply your current energy needs.

    If you don't have a Kill-A-Watt meter or another way to calculate your power usage "device by device", you can use this website to get some decent estimates.
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: New to Wind/Solar, questions about setup.

    Please also note, that small scale wind has a much lower acceptance rate than PV. There are few people who have been really satisfied with small scale wind. The great irony is that if you have enough wind to be useful over the course of the year, (and few do!) you have too much in the sense that the hardware that lives in a harsh environment 365 takes a real beating. Lots of moving parts, subjected to all kinds of loading, and hard to maintain in the field.

    One other note, when going into PV, most people at once and the same time over estimate the amount of harvest they can actually get, while at the same time, underestimating their loads, leading to systems that are too small. The second law of solar power is that loads will grow with time. You never know where the next draw item comes on line,, but be assured that it will!

  • Steven LakeSteven Lake Solar Expert Posts: 402 ✭✭
    Re: New to Wind/Solar, questions about setup.

    Hey, awesome replies guys! You've given me a lot to think about! The biggest one I'm hearing though is to first minimize my electrical footprint, after which I can then focus on how big of a system I actually need after that. I also picked up that the system should be bigger than the present need, which I also figured. Part of my idea for the system's size was to figure out about what I needed to the penny, then size it up about 1/3rd to 1/2 if dooable.

    As for the reason behind going completely off grid, that's not for the day to day living. That's more along the lines of "oh crud, the power's out again." Our local power company is notorious for losing power during storms and taking forever to restore it afterwards. Hence the interest in being able to go completely off grid if need be.

    But either way, I'll take what you guys said, especially about minimizing my footprint, and apply those first before going further with the project. Of course, to do that we first have to get into the new house, and the timing of that will depend heavily on the Realtor. They seem to be having fun dragging their feet on this sale. :(
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: New to Wind/Solar, questions about setup.

    I would only edit what you said in only one way:
    I also picked up that the system should be bigger than the present need, which I also figured.

    I would suggest that you size the system for your needs ONCE you get your loads down as much as possible. You can, with a grid tie, build a smaller system than you actually use, as it will reduce your bill by the amount of KWHs that you actually generate, so a grid tie system does not need to be sized for the total load.

    The point of the generator is,, even if you have frequent outages and even for several days, a generator is a far cheaper alternative. Like we said, sizing a generator for your peak load would be correct, you don't have to size it for your peak loads as you can reduce the loads as needed, pump water now, run the furnace for a while etc.

    Also consider a demand water heater, preferably one behind a solar pre-heat system.

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