All things Solar (merged threads)

[CJR09]

you still need an inverter unless you move to specialist gear which will cost



unless you are building new thermal solar is still by far and away the most efficient form of energy conversion for domestic hot water

[zilo]

Originally Posted by CJR09

you still need an inverter unless you move to specialist gear which will cost



unless you are building new thermal solar is still by far and away the most efficient form of energy conversion for domestic hot water

specialist gear????

inverter???

I was going to use 240 volts DC to drive the water element in a stock electric hot water storage unit.

How would it know it wasnt AC?

Seems so simple to me...can't see how it wouldn't be better than any convection unit to be honest??

[poppa smurf]

not sure if you could use DC to run your AC element, we couldn't here with a couple of different ones but that may vary with elements???

we have used these....... http://www.altestore.com/store/Charg...PT-Male/p2327/ found them to be okay.

depending on time of year your solar simply may not produce the amount needed for the element.

a better, but more costly way, is

solar - inverter/charger - batteries - water heater.

the batteries will "even out" the fluctuations in the solar generation as well as supply the needs of the unit.

instead of a 3 KW system i would recommend at least a 5KW to stand some chance in winter.

it is simple but it takes a lot of maths and a fair bit of knowledge to enact that simplicity.......

I have been involved in a fair few "stand alone" systems now and a few that are doing exactly what you want to do, with differing success rates.

but don't be put off, try it and let us know how you get on.

I've seen a lot of peculiar setups that work like a beaut.

[CJR09]

you cant use your dc to run ac gear - hence there is still a req for an inverter unless you do as poppa eluded to (still need d/c-d/c inverter) which will be cost prohibitive - entirely possible but the cost benefit just isnt there unless you are going off grid?

cheapest way would be to run your hwc stand alone with inverter output dedicated to the hwc but you are only saving minimal coin (maybe $500-$750) - if you are going to do it may as well grid tie it for a bit extra and have the ability to take a credit for the excess generated that isnt used and you have the top up from grid on those crappy days


well designed solar thermal = 70-80% efficiency energy conversion/m2

solar pv restricted to MODULE efficiency x inverter efficiency = ave <15.5% efficiency energy conversion/m2

[zilo]

Originally Posted by CJR09

you cant use your dc to run ac gear - hence there is still a req for an inverter unless you do as poppa eluded to (still need d/c-d/c inverter) which will be cost prohibitive - entirely possible but the cost benefit just isnt there unless you are going off grid?

I know the difference between AC and DC.

But a water heater element doesn't care which you provide.

My reasoning is connecting photovoltaic directly means 100% goes into heating the water...why have battery stress and inverter losses to simply heat water???

Yes I will be off grid, the water heater will be a 4kw PV system for a 2400w heating element....oversized to always work.

So even at less than 50% sunshine it will still heat the water.

4Kw of panels for the same price as a convection water heater...it's a no brainer which to get...

Originally Posted by CJR09

well designed solar thermal = 70-80% efficiency energy conversion/m2

solar pv restricted to MODULE efficiency x inverter efficiency = ave <15.5% efficiency energy conversion/m2

But you are forgetting that when the water is hot I can dump the charge into batteries.....where do i dump the energy from a convection system when the water is up to temperature?....nowhere.


Roof space is prime real estate in this installation.

I was hoping that someone had tried it and had a few tips, but don't mind experimenting and posting back my findings poppa smurf.

Just can't believe noone has tried it...especially with the woeful grid feed in tarrifs these days.

[poppa smurf]

we have done it around here with varying success, what we found to be most successful was solar - inverter/charger - battery - water heater/household..... using the 240V direct from the inverter to power the element (and household), then the solar charges the batt's when drawdown is low and the batt's power the household at night.

direct solar to house is very tricky and full of problem's, I know because I've stumbled into most of them.

the 12V element has had limited success, longevity has been a big one as power fluctuations without the batteries flattening out the the power waves does the element no good, then there are the "evening" showers when, of course, the sun doesn't shine and the hot water is low.

much better to go 48V if at all possible if you still wish to go this route.

we do some "experimental" trials here, always glad to hear from another person trialling a system that we may not have heard or thought of.

I won't post "tip's" as Forum's can be a very argumentative place.

[zilo]

@poppasmurf-Picture this config...

I will be using 240V DC direct from a string of 10x 200 watt panels ..so high voltage DC not a low 12v system.

I can fully understand how a 12v element would be marginally successful as it would take enormous Amps to get 2000 watts of heating that way.




.

[poppa smurf]

let us know how you get on.

[CJR09]

Originally Posted by zilo

I was hoping that someone had tried it and had a few tips, but don't mind experimenting and posting back my findings.

Just can't believe noone has tried it...especially with the woeful grid feed in tarrifs these days.

there's more than one way to skin a cat so to speak

Plenty have tried it - good luck & all the best with it

[LG17]

Just received an email from the company I got my system through.

This is it:

"Title: Product Recall

Please check if you have one like the picture.

Regards"

Attachment:

12/05/2014

URGENT ATTENTION
***** PRODUCT RECALL*****


Today we were notified of a product recall of item AV/DC4P25A DC Isolator. We have been instructed to advise our Solar customers to shut down their systems. PLEASE FOLLOW SHUT DOWN PROCEDURE IN YOUR MANUAL.
This DC Isolator is located next to your inverter (Please turn off ) . This matter is in the control of the Distributor of the Product and the item will be recalled we will be supplied with a new DC Isolator and as soon as possible this will be changed.

[comagutsa]

hey WA guys
if a house has the 47cents contract in place and someone else buys the house is the solar contract transfered to the new owners of the house??

[eaglem]

Originally Posted by comagutsa

hey WA guys
if a house has the 47cents contract in place and someone else buys the house is the solar contract transfered to the new owners of the house??

Not sure the contract can be transferred as the original contract was between the original owners and Western Power so the new owner would need to draw up a new contract and that would at today's unit rate.

[poppa smurf]

Originally Posted by comagutsa

hey WA guys
if a house has the 47cents contract in place and someone else buys the house is the solar contract transfered to the new owners of the house??

no, the tariff cannot be transferred, the new owner must renegotiate with their power suppliers.

[comagutsa]

Originally Posted by poppa smurf

no, the tariff cannot be transferred, the new owner must renegotiate with their power suppliers.

so in other words they will get the usual WA 8cents
cheers

[supershifty]

Same in QLD poppa. Initial FIT is not transferable to the new owner, and you cannot take your existing system from the roof and enjoy the original FIT on your new home. It's address and original owner specific.

Cheers!

Edit: comagusta, yep to your last post - way it is bro.

[EgoFG]

Same in NSW, but please understand that for me, the 66C Gross FIT was not viable due to inflated install costs, only when the Gross FIT was dropped and the 6c NET FIT was introduced did install prices drop sufficiently to get the payback period below 3 years

[poppa smurf]

unfortunately mate that's the way it is......new contract with the purchaser.

I smile when I see a house for sale that advertises solar that "guarantee's no power bill's e ver with a $0.52c FIT".

often wonder if the salesperson can be sued for false advertising when the new buyer doesn't receive said $0.52c FIT.

[LG17]

With the total lack of information from the solar people about my recall I started searching the web. It's strange how I haven't seen anything at all on the news about it.


http://www.dksh.com.au/htm/388/en_AU....htm?Id=553690

[LG17]

...and after contacting the suppliers and sending photos of my switches it appears that mine are heavier duty and not affected by the recall. Apparently the switches are mainly used on smaller installs.

[AlanD]

Originally Posted by zilo

@poppasmurf-Picture this config...

I will be using 240V DC direct from a string of 10x 200 watt panels ..so high voltage DC not a low 12v system.

I can fully understand how a 12v element would be marginally successful as it would take enormous Amps to get 2000 watts of heating that way.




.

Hi Zilo,

Your 10 panels should (will) produce about 350 Volts DC. (Somewhere I have a spec sheet for the panels on our roof that, from memory, produce approximately 40 volts d.c. open circuit, this falls a bit when the load comes on.

The heater in your storage tank will have an insulation rating for 240 V a.c. which means it is able to withstand potentials of 340 volts or there-abouts. So they ought to be OK for the nominal 350 V d.c. (There is always some "safety" headroom in the design). But of more concern is that the (usual) heater element is designed for 240 volts and so will (try) to draw a larger current than its rating. This is likely to be inexcess of the panel's capability and there will be heating effects in the panel for which they are not designed. If you limit the panel string to 6 or 7 panels you should avoid this problem. This would provide 1500/1750 watts if you are using the more modern 250 watt panels.

Another problem will be with your thermostat contacts which are designed for a.c. and any arc that gets drawn when the contacts open is extinguished when the voltage waveform passes through zero volts. With d.c. this does not happen and thus any arc is maintained. This causes rapid erosion of the thermostat contacts and failure. One failure mode is that the contacts get welded closed and thus heating continues until some other fault appears. This might be, if the storage container is a pressure vessel, rupturing of the tank because the increasing water temperature causes expansion and thus increased pressure. Very hot water can also be a real hazard to people, especially if they are not expecting the very high temperatures. Particularly at risk are young children in baths who turn on a hot tap. d.c. thermostats are available, I believe, and I would counsel that you retro fit one of these if you proceed with your plan to directly feed the heater element from the panels.

Incidentally, this arcing business is the reason why you should always start the isolation procedure for a PV grid tied system by opening the a.c. switch or miniature circuit breaker on the output side of the inverter. This causes the input current to the inverter to drop to zero and thus no risk of arcing when the d.c. isolator(s) are opened.

Cheers

[Sam_Boss260]

I got an email from one of the solar companies that were quoting me, stating that the Govt will be dropping the $3,900 rebate so after July 1 the cost of a system will go up by the cost of rebate.

Is this true or s sales ploy to get me to sign now?

[poppa smurf]

all sorts of things in the pipeline regarding solar and renewable energy as a whole, some true, some not.........but the earlier you buy solar the better off you will be.

[comagutsa]

suck to be then buying a new house then

[ute83]

Originally Posted by comagutsa

hey WA guys
if a house has the 47cents contract in place and someone else buys the house is the solar contract transfered to the new owners of the house??

Here in Victoria the feed in tariff stays with the residence, so yes.

[supershifty]

QLD govco rolled the 8c FIT last night, think it ends in July. Those who signed up on the 44c FIT remain untouched - for now.

Wonder how long until this creeps over the border into the rest of the country?

http://www.heraldsun.com.au/news/nat...-1226925963793

[EgoFG]

Already in in NSW, and it makes the installer more competitive, driving prices down !

[poppa smurf]

this will be nation wide shortly, power industry is too strong now.

gas prices are set to skyrocket, petrol is shooting up at least 4c per litre and water is through the roof........not a good place to be anymore.

possibly the suppliers will come to the fore and up the FIT from their side, more competition on that side.......we can only hope.

[buggerlugs]

http://www.couriermail.com.au/news/q...age%7Chomepage
Some very interesting comments at the bottom of the article............

[davenl5l]

at least the sun is shining !!!!!

[poppa smurf]

Originally Posted by davenl5l

at least the sun is shining !!!!!

yes but given the angle of the sun it is producing little,........I produced 6 KW's yesterday.

not enough to cover my usage, winter is coming and along with the increase in supply charge and a slightly higher tariff charge I think I will begin to chew into my credit for a while.