# HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-grid

• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr
No. Wire lengths need to be the same length when they're in a parallel circuit so that each 'branch' has the same resistance (as close as possible). Within any single circuit it all adds up the same.

Thanks Marc.
Yes, you can. Believe me you can. :roll:

I guess..., if it's work related and no pleasure.:p
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

Hi all, hi Marc & Bill,
I haven't posted for a while, my system is running trouble free and the power bill was down to credit.
I have a question; 12 volt system, voltage drop through 1/0 AWG stranded copper wire at 6 meters (20ft) and how many amps could one safely run through that length of 0 AWG?
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

Hi Sacha,

Glad to hear all is well!

Regarding maximum current--There is the NEC (conservative side):

Wire Current Ampacities NEC Table 310-16 (125-170 amp rating for copper)

And there are other charts--Here is one for boats:

West Marine (285 amps--probably exposed wire, not in conduit, etc.)

Note with NEC, you take the current rating of the wire and installed circuit breaker (and derating for conduit fill, etc.) and divide by 1/1.25 for actual maximum continuous load. For example, a 175 amp wire+breaker:
• 175 amp breaker * 1/1.25 = 140 amp max continuous load

Note, if you run a breaker > the 1/1.25 (or x 0.8) derating, it may false trip (perhaps minutes to hours of usage).

And then there is the maximum voltage drop for a length of cable (remember round trip vs one way--different calculators use different measurements... I.e., 10' one way vs 20' round trip). The simple one, for 1/O cable and 10' one way run would be:
• 10', 140 amp, 0.5 volt max recommend drop (12 volt bank) = 0.3 volt drop

For 24 volt battery bank, around 1 volt max drop, and 48 volt about 2 volt maximum drop.

Beware, when you start taking safety factors and "worse case operating conditions into account, the wire requirements increase a lot. For example a 1,200 watt inverter on a 12 volt battery bank with 2,400 watt surge support:
• 1,200 watts * 1/12.5 volts = 96 amps nominal
• 1,200 watts * 1/0.85 inverter eff * 1/10.5v batt cutoff voltage = 134 amps worst case continuous
• 1,200 watts * 1/0.85 inverter eff * 1/10.5v batt cutoff voltage * 1.25 NEC derating = 168 amps branch wiring/breaker continuous rating
• 2,400 watts * 1/0.85 inverter eff * 1/10.5v batt cutoff voltage = 269 amps worst case surge (for voltage drop calculations)

So, all of a sudden, if you want to do the "engineering" calculations, to support a 1,200 watt inverter with 2,400 watt surge, you are looking at almost 3x the "nominal" current calculations for wire sizing (lots of copper, short wire lengths, etc.).

Now, will you use 1,200 watts continuous and 2,400 watt surge every day, all day long--Probably not. But if you ever needed to "push" the inverter to its maximum ability--Then these are the calculations needed to have a "reliable" system.

And it reduces the "surprise" factor down the road...

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Hi Cariboocoot, BB,...,
My battery bank/UPS/inverter is going really well! I haven't paid for electricity in over 6 months now and am actually getting refunds every 2 months, the latest being \$175 AUD/2 months. Considering our power bills used to be \$240 - \$280/2 months we are now saving around \$400 - \$450 every two months. So far all batteries & installation/wiring have been paid off in 6 months and estimating the UPS/inverter/charger to be paid off in under a year. Looking forward to doubling the battery bank and hook up the second UPS/inverter/charger (Victron, bought 2 units for the price of one) and enable us to use microwave, cooker, hot water unit, etc., as well. Also a dedicated OG solar array to charge/keep topped up the bank during the day. I'm still not down to our target of using 8-9 units per day but considering we have no windows in the 7m x 18m shed we live in it's not bad. The 9teen-age son is threatening to move out pretty soon soon too so less of that x-box/computer use will be a benefit.
I truly appreciate all your help, especially Cariboocoot & BB for sharing your experience and taking the time to advise me on the way to independence.
We still haven't completed our house due to economy downturn and xpanding our business (which is doing well, just had to use mortgage for cash flow), but I already buried 2 x power run-in to the house; 1 to be powered purely of the battery bank and 1 just in case we need extra power..., so big switch will be needed somewhere down the line.
I hope you guys are doing well over in the states and aren't suffering too much from the current situations.
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

G'day Sasha!

Nice to hear that all is still going well for you and your family--And your solar power system.

So far, we are doing well, but the political changes to our economic and governmental systems are scaring the heck out of me and have me greatly worried about what our kids will be up against (both family, the the country's next generations).

Regarding your system, did you ever get a hydrometer and start monitoring your battery bank's temperature corrected state of charge?

Regarding your power usage/credits. I am always a bit of kill-joy. I would look at your billing/metering/energy usage very closely to make sure it is "not too good to be true". On rare occasions, our utility has messed up their billing and the customers get hit with a huge "adjustment" (meter misread, for some reason meter not read for months at a time and utility using "estimated" aka made-up readings for billing, etc.).

It is certainly possible given the large spread between between daytime vs night time power rates (\$0.44 vs \$0.11 per kWH???)--Your AU\$175 two month credit would imply a daytime generation of:

\$175 * 1/60 day billing * 1/(\$0.44 per kWH) = 6.6 kWH per day excess power generated during day

That is certainly possible--But just want to make sure it makes sense for your system measurements.

You are certainly "lucky" that the utility actually cuts you a check for retail cost of power generated. In our area, at best, we probably get \$0.05 or so excess kWH check at the end of the year. Nominally, the system is set up for us to "zero out" our bill (we get +\$ and -\$ billing in our account and at the end of the year we either owe money if we have a negative balance or it is set to zero if we have a positive balance).

My guess is that your utility will eventually do something to stop writing checks to you... What has been happening in many areas is the utility splits the bill in 1/2... 1/2 being the cost of power (generation+fuel costs) and the other 1/2 being the cost of maintaining poles+transformers+distribution equipment.

So, your ~\$260 per two month bill turns into \$130 "connection+billing fee" and a "variable" charge for actual kWH consumed (or generated). And, the \$130 per period is a minimum fee (cannot be zeroed out by kWH generation credits)...

Not saying it will happen, but I am reading that this is occurring more often now as GT Solar has become more popular and the smaller utilities are starting to hurt for funds to pay their board of directors/managers excessive salaries and benefits (many do not seem to be paying for infrastructure maintenance :grr).

Next--People start leaving the grid because of high connection fees. Then the utilities start charging "exit" fees (stranding charges/non-bypassible fees/etc.)...

The Solar Surcharge

Then, after customer(s) get so ticked off they do leave the grid, then they find out their local government entity "red tags" their home(s) because is it no longer "habitable" as it has no electricity/utilities (we had a family a few years ago that recycled 100% of their garbage and canceled collection--and found out there was a "garbage service" requirement too:roll:).

Anyway--Very happy to hear that your plans have worked out so well for you. Does not always happen. But with a little bit of pencil and paper work up front--Sounds like you bypassed most of the surprises (and wallet emptying events).

-Bill

Oh--And I forgot to ask... You placed a RCDO Breaker (basically a GFI breaker) on the output of the Inverter/main house circuit input. Have you had any false trips yet (or real trips)?

Like Marc, I prefer my RCD/GFI to be at point of use (sinks, outside faucets, etc. where water/shock hazards are present) vs a single RCD/GFI for the whole home. Nothing like getting a minor shock working around the sink and plunging the whole home into darkness until the breaker is reset.
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire sze for minimum voltage drop, etc.; full house 12v lighting off-gr

Thanks Bill,
I've followed the advice obtained from this thread, mainly yours and Marc's and all is going well. The charging parameters have been set to the type of batteries I use and I never discharge the batteries to below 70%. I keep and eye on the setup and have so far topped up batteries once (a small amount of fluid) and then equalized them.
The bank gets charged to full capacity every night (low shoulder charge per unit).

I have another identical Victron 24/3000/70 unit which can be connected in parallel, master & slave to double the inverter output which would then be 6000/12000. The size of my battery bank (440) is well within the recommended range of 300-700 per unit.

If I were to double that to 880 with two units in parallel I assume I'd have more storage and could therefore charge every other day if we don't increase consumption. Doubling the inverter output would also give me the option of running the kettle, water heater and some other things if the need arises for example power cut.
The other option is to keep the 2nd unit as spare in case one breaks down.

Please note the only wiring carrying 24V is from the battery bank to the inverter/charger and the output is 240V. The wiring/connection between battery bank and inverter/charger I currently have is more than double the diameter recommended for 0-5 meters, the length I have is just over 1 meter.

By running two cables to the house I meant; 1 from the inverter carrying 240V and 1 from the grid mains panel carrying 240V. The length of those is around 12 meters and even those are more than twice the diameter as per regulations. I would like to use the inverter as the main source to power everything in the house but would also want to install a switch to go back to grid power. This could be a manual switch but I'd prefer to automate the switchover when the battery bank reaches a preset DOD. Could this be done via the battery monitor which sounds an alarm when it reaches a preset DOD? Surely that signal could be used to trigger a relay switch!?
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
BB. wrote: »
Oh--And I forgot to ask... You placed a RCDO Breaker (basically a GFI breaker) on the output of the Inverter/main house circuit input. Have you had any false trips yet (or real trips)?

Like Marc, I prefer my RCD/GFI to be at point of use (sinks, outside faucets, etc. where water/shock hazards are present) vs a single RCD/GFI for the whole home. Nothing like getting a minor shock working around the sink and plunging the whole home into darkness until the breaker is reset.

I've had one real trip, accidentally left the extension cord exposed next to a waterpump that developed a leak. Good to know the RCD works.
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

There are a few Battery Monitors that programmable outputs (say ON at 50% SOC and OFF at 80% SOC). Xantrex and Victron are two that I know of (there may be others--I just have not tripped across any at this point)...

Short of buying a really expensive automated transfer switch--Just buying a normal (larger) relay would work (double pole/double throw). You would have the drawback of powering the relay (choice of on grid or on battery) and the transfer time of the switch (could cause a computer or TV to reboot on transfer)....

This gets into the whole problem of automating a system--The costs and drawbacks. And what happens if something fails (more complex systems have more complex failure modes). (i.e., relay fails, and you no longer have access to your backup power)...

Probably, just an "alarm" and an instruction sheet (for spouse, kids, house sitters) on that to do when something happens is going to be more reliable. Or even switching to grid power when on vacation (fridge/freezers/alarms) and let it fail over to battery if grid goes away.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
BB. wrote: »
G'day Sasha!

Nice to hear that all is still going well for you and your family--And your solar power system.

So far, we are doing well, but the political changes to our economic and governmental systems are scaring the heck out of me and have me greatly worried about what our kids will be up against (both family, the the country's next generations).

Regarding your system, did you ever get a hydrometer and start monitoring your battery bank's temperature corrected state of charge?

Regarding your power usage/credits. I am always a bit of kill-joy. I would look at your billing/metering/energy usage very closely to make sure it is "not too good to be true". On rare occasions, our utility has messed up their billing and the customers get hit with a huge "adjustment" (meter misread, for some reason meter not read for months at a time and utility using "estimated" aka made-up readings for billing, etc.).

It is certainly possible given the large spread between between daytime vs nightime power rates (\$0.44 vs \$0.11 per kWH???)--Your AU\$175 two month credit would imply a daytime generation of:

\$175 * 1/60 day billing * 1/(\$0.44 per kWH) = 6.6 kWH per day excess power generated during day

That is certainly possible--But just want to make sure it makes sense for your system measurements.

You are certainly "lucky" that the utility actually cuts you a check for retail cost of power generated. In our area, at best, we probably get \$0.05 or so excess kWH check at the end of the year. Nominally, the system is set up for us to "zero out" our bill (we get +\$ and -\$ billing in our account and at the end of the year we either owe money if we have a negative balance or it is set to zero if we have a positive balance).

My guess is that your utility will eventually do something to stop writing checks to you... What has been happening in many areas is the utility splits the bill in 1/2... 1/2 being the cost of power (generation+fuel costs) and the other 1/2 being the cost of maintaining poles+transformers+distribution equipment.

So, your ~\$260 per two month bill turns into \$130 "connection+billing fee" and a "variable" charge for actual kWH consumed (or generated). And, the \$130 per period is a minimum fee (cannot be zeroed out by kWH generation credits)...

Not saying it will happen.....
Your calculations are most probably correct but you forgot to take into account the governments contribution of \$0.40/unit on top of the base charge per unit which is around \$0.8409 + 10% GST. which they have guaranteed for 10 years. So no, it probably doesn't make sense to think our system produces 6.6kW excess per day.

We opted to go on a scheme called smart power where we have 4 different tarrifs; SUMMER: 9pm-7am \$0.127 + GST, 7am-11am \$0.222 + GST, 11am-5pm \$0.417, 5pm-9pm \$0.222, weekend 7am-9pm \$0.188. In winter the peak times and weekday shoulder get swapped. We could have remained on a flat, A1 tariff of just over \$0.22, 24 hours a day but the Smart Power suits us due to it costing us only half to charge batteries at night.

This is the main reason I've installed the system and am charging the batteries from main grid. So we are not actually generating that much excess but the government tops up the refund. This was put into place to encourage households to switch to solar and be able to pay off the install within 3-5 years. This government initiative was phased out within days of our installation so we were lucky to have it completed when we did.

They have since the deadline halved the incentives upto a capped number of installs to some households who missed the deadline due to high demand, where a lot of scam companies were promising install before the deadline but couldn't deliver due to high demand. Now all they are offering is a one off payment to discount installation and no more \$/unit. Ideally, when the money is there I'm considering an off grid setup to charge from. We hopefully have another 8 years of free government money but I'm dreading every time the government changes here, they may stop their contribution through the solar incentive scheme if they have to cut spending.

Needless to say we are being monitored as far as putting units back into the grid is concerned. We only have a 2.2kW GC array and if we exceed the anticipated number of units returned to the grid the contract would become void. In other words; if I add panels to our system, registered as 2.2kW we lose the lot. We did receive an enquiry letter several months ago questioning the systems capacity and occupancy of the premises. They probably think none lives here yet, they may even send a drug squad out to see if we are growing crops and keeping them warm overnight because we consume more units at night then throughout the day, lol. I think it was a good idea with charging overnight and hope that we did get one over the big guys. Anyway, my friends say it's a brilliant idea. We just hope it lasts for the duration promised.

Our government, probably like every other, have a tendency to introduce things like LPG conversions to cars for example and offer generous incentives only to later phase them out. When we had our LPG conversion (actually addition since the 4WD runs on diesel), LPG cost around \$0.40/liter and now its around \$0.70/liter. Once they got a lot of people onto LPG they gradually reduced their contribution to 0.

We received an initial grant of about half the cost of system & installation and also tax cuts to LPG to make it look like the cheaper alternative but over the course of three years the tax cut was gradually phased out. LPG is still around half the price of diesel or ULP but you do use more of it to power a car so it's not a like for like comparison by any means. I'm still happy with my conversion though as it really shines when towing due to around 20% extra power as the diesel burns cleaner and more efficiently with the addition of LPG. I think a standard diesel engine only burns about 80% of the fuel but with the addition of LPG around 95% wich results in less emmisions and better fuel consumption.

Sorry to go off topic here.
Have a g'day Bill and Happy Easter.
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Sacha,

Sounds like have paid close attention to all of the rules. Hopefully, they will be stable in the future.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
BB. wrote: »
Sacha,

Sounds like have paid close attention to all of the rules. Hopefully, they will be stable in the future.

-Bill

Woohoo,
Average daily down to 7.9 units over last 2 months.
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Congratulations. I assume you mean 7.9 kWH per day average--Are you planning on a larger solar array? With your incentives (as you are grid tied), it may not be required.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
BB. wrote: »
Congratulations. I assume you mean 7.9 kWH per day average--Are you planning on a larger solar array? With your incentives (as you are grid tied), it may not be required.

-Bill

Thanks Bill! That's right, 7.9 kWh/day. Definitely planning on a larger array but will have to be separate/off grid. Due to our contract, if we add to the GC the incentives would cancel all together. Our GC installation was just in time before the government reduced the buy-back incentives by half and then within a few months went down to 0, due to budget. The government are still offering grants on installation cost but no more buy-back per unit. Unfortunately, the 2.2 GC was all we could afford at the time. Eventually, when we can afford, I'm planning to install 2-3 kW OG to power most or all of our needs and let the existing GC pay for it by returning all it can generate back to the grid.
We've had refunds up to \$160 every 2 months but the last bill we were \$1.50 in debit, due to miserable weather.
I have to start working on spread sheets now we've been running for over 1 year with the UPS & battery bank to see the savings. I'm confident the battery bank has been paid off and some of the cost of the UPS. I want to work out the amounts as in: full cost of the system minus the savings. The saving I'll work out based on the amount we would have been paying if we were on the grid with no solar, add the refunds and then I should get a realistic pay-off period.
From the refunds alone we could replace half the battery bank per year which is great considering the savings are nearly double that. For example; we got a refund of \$170/61 days, if we didn't have solar/UPS/battery bank charging overnight our bill would have been around \$120/61 days. in this example our savings would then be \$290/61 days. I have to calculate an average yearly to spread the units generated across the whole year (sunny days & cloudy days) and then divide this into 12 months or alternatively into 6 periods to show savings for the same periods as billed. Is this the correct way of looking at it?

Our heating is via ethanol heater at around \$1-\$1.50 a day and the HWS is currently 3 phase/12kW. We only use the HWS in the bathroom and heat water in a kettle for the kitchen. I already have 4 x point of use small HW units to be installed 1 x kitchen, 2 x bathrooms and 1 x laundry. Water is free via 275000 liter rainwater tank but we do have to pump it via 650w pump with 10 liter pressure tank. The washing machine is always on cold water and gets used before 7am on cheapest rate or weekends on low shoulder rate.
We've used more insulation then required, some places double so cooling will be done via ceiling fans and airflow as the design is based on passive solar placement and have double glazing throughout.
It would be nice to have a small raised water tank, filled via solar pump during the day and then use gravity feed to the house. Problem is; one bathroom is on the second floor so that will still remain on pump.
Temperatures here are currently close to 0 Celsius overnight, around 12 during the day and in summer it's anything up to peak 48 degrees Celsius, average around 30.
• Super Moderators, Administrators Posts: 30,037 admin
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

It does not take that much energy to pump water for a bathroom... Sort of depends on your usage... Sink or shower or tub, etc.. If you have RV (recreational vehicle/caravan/etc.) equipment dealers, you could probably find a reasonably priced 12 or 24 volt pump (marine parts too).

For hot water--You should really look around and see if you can find the equivalent of these Heat Pump Water Heaters (GE Geospring, retrofit type, etc.).

Heat pump is about 2-3x more efficient than pure resistive heating--And depending on the cost of electricity and fuel(s) in your area--A heat pump water heater can meet or beat a "cheap fuel" water heater and even be competitive with solar hot water (lots of plumbing/pumps/collectors).

If your room/basement is cooler than ~55F (~13C) a heat pump water heater may be less efficient (or fall back to resistive heating). The "waste" is cold/dry air. Great in hot climates, not so good in cool climates (may need to bring in outside air to avoid a too cold room/basement--especially in winter).

Cost of power--Whatever makes sense for you... Much of the Grid Tied type solar power systems only make sense as long as governments force utilities to give "good deals" to their power customers. As GT Solar becomes more popular, we are reading that more and more utilities are starting to push back and limit the amount of savings that a GT system can provide (and, in many cases, even limit the return on investment extreme conservation measures...

For example, if a home has an average power bill of \$100 per month (~500 kWH per month in Northern California)--We can reduce our bill to \$4.50 per month pretty easily (minimum monthly charge). Or ~\$0.20 per kWH.

For the utility, it costs them (very roughly) \$50 per month for the wire, maintenance, billing, etc... And ~\$50 per month to pay for generated power.

We are seeing utilities redoing the billing where we would have \$50 per month minimum charge and \$0.10 per kWH charges (and, perhaps \$0.05 credit from solar for avoided fuel costs).

If I had to pay \$50 fixed fee--That is more than I was paying for my home before when I was doing "extreme conservation" of electricity. GT Solar would not make sense, and my conservation would not make near as much sense either...

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

All make sense Bill. The heat pump system would be great in summer if the bypoduct is cold air.
Our supply charge is around \$26/2 months. I can imagine not much saving without the governments buy-back scheme. Still, solar systems have come down in price a lot since the scheme was discontinued. Companies say it's due to technology advancements and buying power but I think the bottom line is more along the lines of overinflated install prices during the incentives scheme and then reverting to more normal pricing once it was over, otherwise they wouldn't make many sales. We were lucky to have found a quality installer as many got badly burned during the governments scheme by companies who ended up supplying low quality components, bad installations or most of all; couldn't install before the cut-off date because they signed up too many installations. A lot of consumers paid deposits on systems only to be then told they won't get the rebates because their installations have been delayed past the cut-off. Overinflated pricing during rebate periods are quite common here. There have been grants for upgrading house insulation, LPG conversions on cars, etc.. All came down in price dramatically after cut-off, some possibly due to overstock but most was just pure greed.
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

;)ALL THANKS TO THE GREAT MODERATORS'S OF WIND-SUN.COM ADVICE; CARIBOOCOOT - MARC, BB - BILL AND ALSO A NUMBER OF MEMBERS WHO HAVE CONTRIBUTED TO MY THREAD.
PLEASE NOTE; MONEY IS NOT THE MAIN AIM OF WHAT I HAVE ACHIEVED AND STILL WANT TO ACHIEVE (IT HELPS TO SAVE SOME) BUT INDEPENDENCE & THE KNOWLEDGE OF CONTRIBUTING TO PRESERVATION IS PRICELESS. :-)

Hey, the Australian government tried to half their buyback incentive a couple of weeks ago due to cutbacks, etc. It was already all approved and announced as definite but then 2 hours later they reversed their decision. Phew!!!
A lot of people started teaming up to file a big lawsuit against the government trying to renege their 10 year guarantee. I guess it would have ended up costing them more in legal fees than worth.
Just shows that a governments word can be taken pretty lightly if at all. Worry every time there's an election, caucus or other political games going off.
Our system was what we could afford at that time, 2.2Kw but there are people out there with roofs covered to the brim with solar panels, who have spend \$20000+ after rebates and they would have been hurt badly because all of a sudden their payoff period could have gone from say 4 years to 15 years.
I'm very happy with our set-up, just wish we could have afforded a larger one.

Our bills so far:
Nov 2010 - \$211.70 debit
Jan 2011 - \$262.75 debit
Mar 2011 - \$270.90 debit
May 2011 - \$251.90 debit
Jul 2011 - \$326.30 debit
Sep 2011 - \$194.15 debit
Nov 2011 - \$42.65 debit
Jan 2012 - \$4.00 credit
Mar 2012 - \$96.05 debit
May 2012 - \$29.20 debit
Jul 2012 - \$69.85 debit
Sep 2012 - \$7.40 debit
Nov 2012 - \$108.80 credit
Jan 2013 - \$131.35 credit
Mar 2013 - \$170.50 credit
May 2013 - \$28.95 credit (credit accrued \$439.60)
Jul 2013 - \$1.55 debit
The OG solar was up and running in August 2011 and then the UPS & battery bank in June 2012. Some data from our bills: (beginning to end of) Sep 2010 - Sep 2011 debit \$1517.70, Sep 2011 - Sep 2012 debit \$237.15 Sep 2012 - Jul 2013 credit \$438.05.
I'm looking forward to the next bill to complete the cycle, \$2000/year difference from BEGINNING OF OG solar installation would have been nice but I'm more than happy with it. So far we have paid of the OG solar in two years rather than 3.5 years as estimated (that was the estimate from the installers point of view which I would have more realistically capped at 5 years). I'm now estimating to have paid off the whole set-up in under 5 years, this would include all parts, wiring, 2 x Victron UPS's and the battery bank, needless to say I am not using the second Victron yet; currently only 1 is hooked up until we can afford to double the battery bank. This I may now leave until after the life expectancy of the existing battery bank, rather than join a new bank to the old one, which I understand is not good practice after more than 6 months as the new bank will only perform as well as the old one.

I hope this thread I've started will encourage others to follow and learn from it as I have.
I'll submit the final figures next month, when we get our bill. I'm not expecting a credit due to bad weather and very little sun but who knows, the teenage son passed his drivers licence recently so he doesn't spend too much time on his computer, x-box and such, all with lights on most of the time.
I'm now looking forward to starting some passive solar heating (winter) projects and soon test the design of the house, incorporating numerous airflow vents (summer). So far no air conditioning, even though Western Australia needs it in summer. Maybe we've all gone 'too soft' with all the mod-cons available now, people have lived without them for centuries!

Anyone out there; what incentives does your country give you to go solar?
I think we are pretty fortunate here, in Australia, for the time being. There hasn't been many sunny days lately but we've accrued enough credits to not to have to pay for electricity and hope to maintain the battery bank so it'll work a few years. I'm happy with free electricity, even if our credits are used up during winter.
PS; Electricity went up by around 30% in the last 2 years which has not been accounted for in my estimates.
• Banned Posts: 17,615 ✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Good to hear a success story! You're entirely welcome.

Now, where's my free kangaroo?
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

I have a few euro's depreciating in my wallet but nothing bigger. I'd try to get you one of these but too big for the wallet or to post via USPS; http://www.1tonnegoldcoin.com/ . Trust me, I've seen the thing.
Besides, currency here for mates favours is Corona (normally carton of 24 bottles), still too big for the wallet but normally doesn't last long enough to stow away. 'Mates Rates'!
If you still insist on the kangaroo, I'll go catch one, there's lots of them every evening up the road. We get a stray one every now and then crossing the property but not too often as most of the properties around here have rural fencing, dogs, horses, etc..
Anyway, I think we've discussed this; they don't fold very well, especially the bigger ones, except for the black ones.
You may not get the latter one so I'll explain; We came to Australia 9 years ago, actually on the day 23rd of August, yesterday coinciding with our 20th marriage anniversary. Landed in Sydney, NSW, bought a 4WD & caravan, travelled across Southern Australia and 3 months later ended up settling in Perth, WA. Along our travels we met some great people, some of which keep travelling around Australia for years, some over and over again. We're looking forward to doing this one day, to see the North of the country as well. the furthest we got North is Ningaloo Reef in Exmouth, once or twice a year for holidays.
At some point, over a camp fire, this guy asked if we've seen a black kangaroo yet, they are apparently everywhere?
It turned out to be the triangle caution road signs warning against kangaroos on the road. 8) Wise guy!!
Pity to see so many killed on outback roads, sometimes one has to dodge the carcasses on the road. Generally it's advised not to travel at night because one theory is; the things when ending up in front of a vehicles headlights get terrified of their own shadows and end up running towards the light, away from the shadows. Not very 'bright' eh?
• Banned Posts: 17,615 ✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Ours are moose, elk, and hedgehog.

By the way a "free kangaroo" can also be interpreted as meaning "one not in captivity", so leave 'em hopping 'round the outback, mate.

(How many just cringed at that joke?)
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

only signs around here are for children and deer.

i was half expecting sascha to say it was put on the plane but jumped out and went splat.
• Solar Expert Posts: 3,123 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
niel wrote: »
only signs around here are for children and deer.
Which is absurd, since neither of them can read very well.

Actual sign down the road a ways, near me: "Caution, suicidal deer ahead"
SMA SB 3000, old BP panels.
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

like moose, elk, and hedgehogs can? you played on the wording.

"Actual sign down the road a ways, near me: "Caution, suicidal deer ahead" "
ok who is arming the deer or do we have a veterinary dr kevorkian out there?:p
• Solar Expert Posts: 3,123 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
niel wrote: »
"Actual sign down the road a ways, near me: "Caution, suicidal deer ahead" "
ok who is arming the deer or do we have a veterinary dr kevorkian out there?:p
Just like some people do, they jump in front of cars or buses. Trains don't count for this.
SMA SB 3000, old BP panels.
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Hi guys,
All is well with my battery bank/UPS, so far no problems. My only concern is the loss of electrolyte and may have to reduce charging parameters. How much distilled water would one expect to use monthly? My battery bank is 24v/880Ah in total; 8 x 6v/220Ah batteries. I use about 0.35 litres per battery per month. I have a timer programmed to charge for 2.5 hours every night which brings it from around 75% to 100% SOC. I top up batteries once a month in the morning when they are full and then give them a longer charge/ equalize.
The victron uses adaptive charging with variable absorption time and it gets to float before the end of each charge.
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
Sascha wrote: »
Hi guys,
My battery bank is 24v/880Ah in total; 8 x 6v/220Ah batteries.

I meant 24v/440Ah
• Solar Expert Posts: 5,182 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

the wet cell guys will chime in , but that does not seem excessive given you are at higher avg temps than most of us so your batteries get hotter sooner than up here.
If you re worried you could back off the voltage a point or so and see what happens, but it sounds like you are nicely balanced, battery to loads to PV

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
West Chilcotin, BC, Canada
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

Thanks westbranch,
I slipped off once, the electrolyte went to just below cell height, oops! Next time I top up I will also reset the battery monitor.
So tell me about charging & cycles, I hope each night doesn't count as a full cycle..., I hope not as I'm only depleting 25-30% maximum every day?
• Solar Expert Posts: 298 ✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g

First off, I will admit that I did NOT wade through 24 pages of responses to your original post.

But I DID wire my cabin for 12 volts (and thankfully 120 volts) as well.

This was 1992 and inverters were expensive, inefficient and scarce at that time.

I used #14 wire (common here in Canada) for the 12 volt wiring with the longest run perhaps 30' or so.

My intention was to run a 13" 12 volt TV using this wiring.

I quickly determined that I would lose 1/2 volt with just a 500ma load. The TV was 7 amps, meaning that it wouldn't run from a 12 volt source due to line loss dropping the input voltage to maybe 11.

I considered running 18 volts into this wiring just to make it work......

And then I bought an inverter.

With 120 volts, appliances are far cheaper, line loss is minimal (hey you are running 240 volts it would be even less than mine) and standard receptacles and plugs can be used rather than the polarized versions needed for dc.

So what do I use that 12 volt wiring for now?

Charging a cell phone.
Island cottage solar system with 2400 watts of panels, 1kw facing southeast 1kw facing southwest 400watt ancient Arco's facing south.Trace DR1524 MSW inverter, Trace C40 PWM controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 27th year.
• Solar Expert Posts: 121 ✭✭✭✭
Re: HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-g
706jim wrote: »
First off, I will admit that I did NOT wade through 24 pages of responses to your original post.

But I DID wire my cabin for 12 volts (and thankfully 120 volts) as well.

This was 1992 and inverters were expensive, inefficient and scarce at that time.

I used #14 wire (common here in Canada) for the 12 volt wiring with the longest run perhaps 30' or so.

My intention was to run a 13" 12 volt TV using this wiring.

I quickly determined that I would lose 1/2 volt with just a 500ma load. The TV was 7 amps, meaning that it wouldn't run from a 12 volt source due to line loss dropping the input voltage to maybe 11.

I considered running 18 volts into this wiring just to make it work......

And then I bought an inverter.

With 120 volts, appliances are far cheaper, line loss is minimal (hey you are running 240 volts it would be even less than mine) and standard receptacles and plugs can be used rather than the polarized versions needed for dc.

So what do I use that 12 volt wiring for now?

Charging a cell phone.

Hey 706jim,
Looks like you are a VET of sustainable living. I don't expect anyone to go through 24 pages of my 'learning curve/apprenticeship' but hey, I think I got it right first time, all due to the help of moderators & members here. My setup is going strong, touch wood, for many years to come. It's not exactly right 'the first time' though considering I bought wire, 12 volt LED downlights & fittings for the whole house. I am using the cable I got for 12 volt to link all the downlight clusters to central LED drivers 240v-12V and run them of the inverter. It will probably be a few years yet before I start using my second inverter (2 linked together for extra inverter output) as I don't want to mix 2 year old batteries with new ones. For the time being I am happy with what I am powering: freezer, refrigerator, lighting, water pump, TV. Still living in the shed though so once house is finished I will probably expand. I'm running 2 x mains power lines to the house; 1 from the inverter setup and 1 from mains, for security & flexibility, just a manual switch to alternate. Also planning on a separate OG solar setup to charge when sunny.
Hindsight; I wish we could have afforded a larger system when the government was giving away all those incentives, I think they capped it at max 5 or 6 kW, we could only afford 2.2, just before the deadline of incentives. Needless to say the prices of solar came down pretty much straight away but my pay-off period stood at 3.5 years (realistically 5 years I would say). Still, I'm on target to pay off within 3.5 years, including the add-on battery bank/inverter setup. The batteries I have were pretty cheap (got them direct from authorised state warehouse as I was re-selling them at the time and the more I sold the lower my pricing), Supercharge Amp-Tech GC2-6V and may eventually go for something better. Still, if these last 5 years I'm happy to use the same again!
Sorry to go on & on...., another page to read for you! 8)