How many people here live in a off the grid house (not a boat)

[rossd 16]

We have brought a section and planing a new 90 sq m house for just 2 of us. Town section with services at the gate. Was going to go the whole hog off the grid  but having second thoughts now and maybe just go thermal panel, wet back hot water and grid for the rest with maybe gas hob. We have got 2.75 Kw PV grid connect in our present house which has been OK but hard to set up well in an existing house. I have been through a rather interesting exercise in the last couple of months measuring consumption of different appliances around the house.  Being a avid tea drinker rather shocked on the electric jug consumption. Then a again the Elcold freezer was very economical although the garage was a bit like a freezer anyway! To make PV really  hum you need to reduce consumption especially at night but to just reduce consumption while still on the grid virtually will give as good a result without the considerable expense.  We already dont havea TV and dont use the dishwasher, cold wash clothes and with well insulated new house and woodburner no electric heaters and dont believe in heat pumps.   

[AlastairW 15]

Have been living completely off grid for the past 6 years. We live rurally. My background is in electronics/electrical systems, so I designed and built the system we use ourselves, and have done a bit of consulting for others looking to go off grid.

 

For what it's worth, living in town, with power at the gate, it doesn't make financial sense to go off grid. It was going to cost $30k to get power to our house, I put in a complete system, including a large battery bank, for that.

 

We designed and set up the house with off grid living in mind. We don't do without any of the normal comforts of life, run a dishwasher, two freeezers, TV, etc etc. None of our appliances are the expensive really low power usage types. Best thing we did though, was to overspecify insulation for the roof and walls, and get the best double glazing we could find locally. Heating is a single woodburner, and we expect to be able to sit around in the depths of a Southern Winter in a tee shirt.

 

I have to disagree with the idea that making PV work is about minimising consumption though, what quickly became apparent to us was that you just become smart about when you use power, for instance, you run the dishwasher in the morning, so you have the rest of the day to make up the power used. Stuff like that. And yep, if you look at the power that the jug or toaster use, in ampere terms it's pretty well up there, but the time that they are consuming power for is limited, and with a battery back-up, it's all about ampere-hours.

 

We discounted the feel-good value of going off grid, it had to make financial sense, but must admit to feeling a bit smug sometimes when there's a power outage locally, and we're the only ones with lights on.......

[marinheiro 352]

from a financial point of view, if you compare Alastair's $30k initial investment funded at an interest rate of 6% vs a monthly power cost of say $300, and assume there will be an annual increase to this cost of 2%, then the solar install is at break even after ~10 yrs. This does not consider any maintenance costs and I would expect after 10yrs the batteries will probably need replacing

[rossd 16]

You have obviously spec'ed your system high Alistair and no need for energy efficient appiances but anyone on grid such appliances may well pay for themselves. We will probably buy a Gram fridge which is about $500 more than a regular fridge. Also studying up on fridge/ freezer installation which is still at the shove in hole and plug in stage where as putting a hole in the floor and venting up through the ceiling and or roof is reccomended. By reducing consumption i mean not only smart use but comonsence use which apears to be beyond a lot of people. We have some friends with a off the grid holiday batch, what a nightmare , even after a conserve power lecture guests will go out and leave lights and tv on!

[wheels 543]

AlastairW is the first truly accurate post I have seen on this subject. I have several friends that have large Solar systems. One lives totally off grid, as they are in the remote Hill area;s out between Nelson/Motueka. The other lives in Blenheim and produces power back to the grid. The later has a very sophisticated computer monitoring system that returns so much info, it can darn near tell you what you had for dinner.
Basically, if you take install cost and on going maintenance and then end of life replacement into account, the cheapest way of powering your Home is by the Grid. If you then want to make savings, then simply be as efficient as you can or want. Where Solar comes in to a cost saving is if you live remote and the cost of getting power to the House is going to be really expensive and thus a Solar system is on par or cheaper.
With my friend that lives in the Town, His system his a small 2.5Kw panel system and He installed it more as a learning thing than wanting to save power costs. The first stage of his install was with out batteries. After a lot of discussion with him, he soon learned that Batteries were a very important part of the system as well. But that doubled the cost of his install of course.
There are a couple of points that make it impossible to return money enough to cover the cost and make a profit. Firstly is the pathetic price ration between what the Electricity supplier pays for the excess you make and what they charge for supply. Secondly is the cost of a Bank of Batteries and the discharge point if you want to keep the Bank within parameters for warranty. Although this alters depending on Battery type. For LA batteries, the discharge is only 20%. To make a Bank most economic, the Discharge floor needs to be 50%. For LiPo and the new Carbon Air batteries, the discharge floor is much better of course, but the price of the bank is 2 or 3 times higher.

There are several area's where big savings can be made in the consumption of energy a House requires and Water heating using Solar is one of the biggest. An area that many do not consider in NZ is to upscale this and also use excess hot water for general heating of the Home. I have heard so many stories of people simply having to run off Hot water because they have too much. And at least here in Marlborough, the Council will not allow a system to run over 65degC. They require a cold mix to enter the system so as the system can not over heat. If a Home installed a water heating system that feed to under floor or radiators in Walls etc, much more heating could be done of the Home.
 

[rossd 16]

Agree there wheels with the economics however peovple put in pv for other reasons mostly. We visited a perspn in town who disconnected from the grid in February and i mean really disconnected, they took away the meters and also the wires back to the pole. She is a person prepared to rough it and go without a bit doing washing on a sunny day etc. when my wife heard that she said , no way! Only 8 modules so pretty small. With cylinder temp we had ours up to 80 degreese on a fancy controller but i dont thjnk the cylinder manufacturers are happy about that. I am thinking of unequal pressure with a vent through the roof , 270 litre cap. In the ceiling with thermo syphon for both wetback and panels.

[marinheiro 352]

couple of interesting articles on PV's and solar water heating

 

https://www.consumer.org.nz/articles/grid-tied-pv-systems

 

https://www.consumer.org.nz/articles/solar-water-heating

[rossd 16]

Just a couple of comments there, payback of 5 to 7 years on 10 k system a bit optimistic. We T present might save $100 a month and ours cost more like 17 k. Nof rhat i am overly concerned. I have several times read that thermal and wetback togethwr is a goer. I eseciallt want to keep it simple withoit pumps and controllers

[too_tall 15]

Basically, if you take install cost and on going maintenance and then end of life replacement into account, the cheapest way of powering your Home is by the Grid. If you then want to make savings, then simply be as efficient as you can or want. Where Solar comes in to a cost saving is if you live remote and the cost of getting power to the House is going to be really expensive and thus a Solar system is on par or cheaper.

 

 

 

I totally agree. Currently.

 

What will power prices do in the long term though? They certainly have not reduced over the last few years!. What would the real cost of a solar system be to maintain? Batteries don't last forever, nor do panels. 

From an environmental aspect it would be interesting to know what the real environmental savings are, or are not, by being off grid.

 

NZ has a large portion of its power generated by renewable sources - namely Hydro. That power is non polluting now - the dams are there, and are not going anywhere. New dams create  pollution ( I'm thinking the majority would be diesel burnt? ) in the creation of them, and have permanent effects on the environment by changing the way water moves from source to sea, and also by flooding out huge areas. Once its built, its non polluting, but the environmental changes are forever.

 

What is the environmental cost of building solar panels? Also the batteries, and the end of life issues need to be considered as well.

 

People using solar systems will use gas fired cooking and maybe gas heated water. Log burners for space heating. Potentially a small generator to top up during extended periods of decreased sunlight intensity. The same attitude toward power use that an "off gridder" has would result in very minimal power bills ( although of course, line charges won't decrease ) should they be grid connected. What results in a lower overall cost both  financially, and environmentally?

 

I have not got any answer, and have not looked into this in any real way. But it does come to mind whenever I hear people telling me how cheap off grid is for them, and how they are doing their part to save the planet. Maybe they are genuinely correct. I don't know. I suspect that the reality is not quite what they feel.

[AlastairW 15]

Too_tall

 

Absolutely correct in every way. We went off grid because it was more cost effective in our particular situation.

 

Although by my wife and I are environmentally aware, we went solar in the knowledge that the production of solar panels, associated electronics, and the batteries use huge amounts of resources to produce,and, when their useful life is over, leave some real nasties which have to be disposed of in some manner. Anyone who thinks they are doing it to help save the world needs to get a reality check. My belief is that as far as sustainability goes (and sustainability has to be financially as well as environmentally), there is no real difference between solar off grid and on grid as it stands in NZ.

What we feel very comfortable about though, is independence from the power companies, in whom we have absolutely no faith to maintain market prices at, or close to, their current level.

 

We use gas for cooking, I have a friend who is also off grid who uses electricity. That's fine, you just need to spec your system accordingly.

 

Provided you use good quality components, ongoing routine maintenance costs should be minimal - if you don't take your time into account that is. Cleaning panels every now and again, topping up the lead acid batteries once a month. I know how to look after batteries, we bought good quality, and I expect to get at least 10 years out of them. Six years in and there's no significant reduction in their performance. Likewise with the control electronics and panels. Good quality will last. I'm working on probably replacing the electronics at 15 years, and hopeful that the panels will outlast me! We'll see, We'll see though, I'm an electronics engineer, I monitor what's going on in the system.

 

We get quite amused when we look at all the adverts for solar, and the inferences they make. Companies just wanting to sell product and make money, being imaginative about the realities of solar. Playing on the feel good and cost savings factors, but failing to fully represent the realities around that.

 

Anyway, all that aside, we're very happy to be off grid, and are fully supportive of solar as an alternative means of generating power, which does indeed have it's place in the scheme of things. It makes you feel very close to your source of power, very aware of your power usage, and that is where the sustainability factor really comes in - you know how much power you produce, when you produce it, and when you can use it. Common sense does the rest.

[too_tall 15]

There are several area's where big savings can be made in the consumption of energy a House requires and Water heating using Solar is one of the biggest. An area that many do not consider in NZ is to upscale this and also use excess hot water for general heating of the Home. I have heard so many stories of people simply having to run off Hot water because they have too much. And at least here in Marlborough, the Council will not allow a system to run over 65degC. They require a cold mix to enter the system so as the system can not over heat. If a Home installed a water heating system that feed to under floor or radiators in Walls etc, much more heating could be done of the Home.

 

 

 

I recently did some alterations in the house, and installed underfloor hot water heating. We have a 5000L cylinder ( yes, 5 m3 of hot water ) which was a little pricey, but its heated by solar and also a heat pump water heater ( HWHP )  ( 9KW ). It also has a wood fired boiler which has yet to be lit after a couple of years. Works very very well, mostly solar powered but occasionally the HWHP fires up to top the temp back up to 60 degrees. The wood fired boiler was probably an unnecessary option, but as we are rural and have unlimited wood available, I thought that it could be a great option. The Solar is so effective and the HWHP works so effectively that we just never need it. Or I am too lazy to collect wood.

 

Unfortunately this only heats a modest portion of the house ( only the 90m2 which was renovated and has a concrete pad floor ), and as most of the house has a wooden floor on piles, underfloor heating is not a great option for these areas. I have thought about Radiators, but they are not overly effective apparently.

[wheels 543]

One thing I missed out was that when I refer to things like using Hot water etc, it is as an additional. So in other words, using Solar on it's on is not going to warm the House. But getting some warmth then takes the load off the electrical heating etc. So I see all forms of "free energy" as additional that all combined add up to forms of saving. But I doub't it would ever be economical to retrofit an existing Home. One needs to start from the beginning and combine everything to aid in achieving the over all benefit.

TT, I have a friend that installed small radiators, like the type used for Car interior heating and fans behind each on in each room. He had a Log burner with a Wetback and pump that pumped the hot water around his home. The entire Home was lovely and warm. However, Wetbacks tend to take a huge amount of heat from the fire box.

[rossd 16]

Too tall I saw at a Home Show a system of retrofiting water heating underfloor, well on top of floor actually. Didnt look closely but i think it was pipes embedded in some sort of building sheet that went on existing floor and then a new floor over that.    

[DrWatson 375]

So, our place up the BOI is off the grid, and although we have bugger all draw at this point, we sized the charging etc. for later expansion up to 4.75kW of panels (currently 1.5kW) - which should cut it for a normal energy efficient household.

Currently running a small 24v battery bank (4x 6V) that we will upgrade to 48 volts when we expand

 

I have two Victron c 24/1600 inverters. They will work in parallel to deliver 3200 continuously (6kW peak for ~30s). I say will because I let the smoke out of one early on and that's why I've now got two... The original one is being repaired in Germany.

 

When we change to 48V those two 1600W 24v units will find their way onto the boat.

 

I can't remember the Ah of our battery setup I think it's about 400.

I'm hoping that by the time we increase capacity, the Li (or carbon or whatever) tech will be sufficiently cheap to change over to that - the charge controller will handle it all.

 

Anyway we run a little freezer and some lights, from this, + a 24v water pump.

With six people camping, using the dunny and burning lights until 2am + keeping enough beer cold and running the "stereo" - the controller dumps bulk electrons back into the batteries for about the first 30min of sunlight, and then they're apparently full again and it flicks over to float and whatever the next thing is for the rest of the day.

Have yet to hook up the solar hot water system so showers are still by bucket, but I assume the power use will increase when we do because of the showering.

 

Anyway the whole setup was about 13K (incl. 2kW of panels, all mounting equipment etc., cables fuses, new smoke and a 4.5kW backup Honda to run powertools while building etc.) Tentative connection to grid costs were about 10K - + the monthly connection and all associated costs which for a place used about 1-2 months a year, doesn't really make sense. 

 

Upgrade cost will be probably another 15-20K later on. I'm OK with that. Given that someone here already mentioned the unlikely event that the private power sector will keep fees reasonable, I'm happy to be saving that +100 a month at the moment, and likely to be saving upwards +2-300 a month in the future. Those kind of dollars add up fast

 

 

 

A thing a friend of mine does over here, as a heating engineer (grew up in Nelson). He installed a massive HWC storage, like TT, and he dumps solar excess electricity into it, straight from the panels through some kind of controller - doesn't go via batteries. When the sun shines he heats that water. and he heats it hot. this is then used via a heat exchanger to heat the house. Works a treat - was too scared to ask about cost.

 

One thing you notice here, is that the radiators were often placed below the windows. I've never seen the need for a fan though. the convectional currents stir the air around enough. Also, the walls here are 500mm masonry, with 100-150mm foam plastered on the outside. That thermal mass is really awesome.

[armchairadmiral 411]

We have had solar water heating for 10 years.Had some issues with panel (2 replacements on Wty) and one circulating pump. Original cost was about $5000 on a 2yr interest free deal. We manage it by turning off power ,showering in mornings. Reckon break even was at 8 yrs so it's not all its cracked up to be and we are locked in now if anything else goes wrong because of cost of changing back. Would we do it again. Probably yes. New units much better I assume.

[DrWatson 375]

It was suggested to me that instead of going solar hot water, to just put extra PV panels on the roof and go electric hot water, this might be the future actually, fewer moving parts etc... standard plumbing setup...etc etc 

[too_tall 15]

It was suggested to me that instead of going solar hot water, to just put extra PV panels on the roof and go electric hot water, this might be the future actually, fewer moving parts etc... standard plumbing setup...etc etc 

 

How would the efficiency stack up though? PV panels harvest about 10% of the energy, what does a solar water heating panel harvest? I think its far higher..

[1paulg 17]

I have been looking at a hybrid /grid system with batteries which for a house using around 28KW/day adds up- although the batteries which are Lead /Carbon  and have similar charge/discharge capabilties to Lipo4 but are approx 1/3 the price .. 

I calculate we would need around a 6 KW system and about 14 KW storage which equates to a $30K investment and makes the payback 8-9 years which is longer than the average person stays in one house!  There is a feel good factor as well and I guess it would add some value to the place.. We have a swimming pool heated by a heat pump so I can dump excess energy (to a degree ) in that in the summer when production is high.

  Still assessing - so not committed yet but think it is the way to go..

Systems without batteries are only ever going to cover maybe 40% of your power bill -but Lipo4 does blow the economics away if one goes that way..

[DrWatson 375]

How would the efficiency stack up though? PV panels harvest about 10% of the energy, what does a solar water heating panel harvest? I think its far higher..

 

Yeah, I think the panels are getting more efficient, but true the efficiency is not great. The advantage I think is that you can use the same panel to deliver two things, flexibility etc.

Hot water and electricity.. Need more power? then the space that would otherwise be keeping your hot water cylinder hot goes to your batteries. Batteries full? All that area of your PV now goes into your HWC. The PV is an easier and cheaper install than the solar water, and requires fewer permits etc. (at least for us in Northland). 

[rossd 16]

That's certainly what the solar cpys are saying and some will not entertain thermal modules at all. I think having both is not on but still a place for thermal on its own I think. The vacuum tube jobs are all the rage but i wonder if they have been oversold. I am going to see a place in Huntly that imports flat panels from Turkey of all places and see what he has to say.