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Solar/Wind – Generates Power
Batteries – Store Power
Charge Controller – regulates charging of batteries
Inverter – Inverts DC to AC power and converts AC to DC power
you need batteries. agree with michael – do not cheap out on batteries.
The one component you are missing is a quality generator with auto start feature. This is needed for desulfation of batteries (also known as equalization).
TomOctober 30, 2008 at 12:00 am in reply to: Building a Hybrid System (Solar, Wind, Generator, Batteries, etc.) #64153
you cannot run a geothermal system off the grid. well – let me re-phrase that – you can if you have a lot of money. Here is why….
Geothermal requires the use of compressors (similar to an air conditioner unit). Those compressors require 220/240 volt power, which can only be provided with two stacked inverters…not cheap. Further, the amp draw (not peak surge) is at least 30 amps. This equates to 6600 Watts of instantaneous power, every hour they run through a compression cycle. That is just the compressor. Excluded from that equation are the pumps and monitoring systems. Forgetting all the rest of the stuff (like your home), just to run the compressors you will need the following….a battery bank to store 7 kW of energy. Conservatively assume you will allow your batteries to discharge to 50%, which means you need storage of 14,000 Watts per hour to run a geothermal unit. At 24 volts, this equates to an amp-hour rating of 583. We haven’t talked about the rest of your home yet (fridge, tv, lights, radio, computer, etc.). If you want three days of autonomy, and the compressor cycles for three hours a day, the energy needed JUST FOR THE GEOTHERMAL COMPRESSOR UNIT works out to 583 amps x 3 hours/day x 3 days = 5247 amp-hours….a system to hold that much juice will run you well over 100K..that is just the batteries…you need two inverters which run at least $3,500 each, a battery bank of at least 24 to 36 batteries, at least two charge controllers, and we haven’t even got to the solar panels or anything else….
Geothermal is great – just not for off gridders without a lot of money.
where do you live?October 29, 2008 at 12:00 am in reply to: Building a Hybrid System (Solar, Wind, Generator, Batteries, etc.) #64151
Here are my two cents…i live off grid in Ottawa, Canada – defintely not too sunny here…
Hybrid systems do work for all the reasons you said above (sunny in summer, windy in winter). The question from pigden above is relevant, since if you do have 365 d/yr of running water (with enough power), you don’t even need a generator.
You are building a highly redundant system…solar, wind, possibly water, generator, batteries and grid…if you have the grid, why go off it? It will cost you quite a bit of money to put in the batteries and charge controller, and an inverter to run your home. If you have the grid, use it as your battery. If you are worried about power outages, get a generator.
The type of generator you want for your system is not the same as a backup generator. They are also not “last resorts” for off grid systems, rather, they are integral to the overall health of your batteries. The generator should have an autostart feature, with fuzzy logic – this means that under many different circumstances, it may receive a trigger to turn on – for example – a heavy load with high amp draw, different voltage settings on your batteries, and, most importantly, the generator is used to de-sulfate or “equalize” the batteries every three to six months. My advise is to not cheap out on the generator – it is critical to the health of your batteries.
Yes – I do have a civic number. We built a new house on a vacant lot, and simply went through the normal motions of building a home. This included building permit, development fees etc. We also did our usual electrical rough in and Electrical Safety Authority (in Ontario) permitting.
We didn’t tell the City we were “off grid”, since they are not issuing a permit for electrical hookup. We also did not tell our local utility, since it has nothing to do with electrical either, since we are not connecting to the grid. We did have to tell the ESA, since they are a permitting issuing authority on all electrical things. Foundation, etc., is irrelevant – it is a structural issue, and has no bearing on electrical (e.g., don’t confuse the issues).
I am not sure of the difference between rules in quebec or ontario. If you want to give me your email address, I can email you directly…
Here’s the thing folks (just my two cents)…
Geothermal is great…but…not for off-gridding…the premise being, those compressors are electricity hogs…unless you stack two inverters, you can’t supply the 220 volt power needed for the compressors, notwithstanding the 30+ amps needed to run them. They simply have too much draw. This is the same reason why air conditioners are too expensive to run on an off-grid system…220 volt at 30 amps is waaayyyyy too much power draw….stick with simplicity…solar hot water with a couple of small grundfos pumps, energy efficient heat exchanger…that is doable…220v and 30 amps, though doable, is too expensive for many people to supply…
I live in Ottawa. We live in a 2,800 sq. foot home totally off the grid. Nothing fancy. Standard home, stick frame, wood heat (when I have the wood), a 1300 W array, 3.5 kW inverter, 2400 amp-hour battery bank at 24 volts…
yes – totally doable. I have a 2 year old, and another on the way….yes…it is easy to do, takes little lifestyle change, and did not break the bank. i am permitted through the Electrical Safety Authority, and did everything above the board….
we are off the grid in Ottawa, Canada. Nice family home, 3 bedrooms, standard size and construction…my two year old isn’t complaining either.
We love it. We had 4.3 m of snow last winter and managed just fine…my mom on the other hand had four major power outages! nasty! i am just happy to not be paying money for an unreliable power grid!
why place them on the roof at all?
I live off the grid in Ottawa Canada, and snow is an issue…if you don’t have to place them on your roof, then why bother? I would only recommend roof mounting if you are worried about damage or have no room….
Here’s the thing…
You don’t have to build your own home, hunt your own meat etc., nor do you have to be a billionaire like Bill Gates to be off the grid. These are the most common perceptions of off grid living. I live off-grid in ottawa, canada with my wife, two year old and another one of the way. We have a mortgage, full time jobs, kid in daycare etc. We built a normal home, we power it with solar energy and are totally off the grid. Off the grid does NOT mean being a hermit, in my mind. We are not talking about extracting ourselves from society, but we are talking about greater self-reliance and greater stability when it comes to power and heat. I am no longer concerned about big snowstorms shutting down power lines or anything like that. We did no sacrifice anything, nor did we break the bank on the home…there is a middle ground that can be easily achieved. Your “average” person will not be able to build their own home (nor will they have the time), and your “average” person does not have millions in the bank to build a huge energy system…