Solar Power and Hot Water Heat Pump

[Kiwi Phil]

Anybody put in either;

1. a Solar Power System on their home (that will feed back in to the grid when you are not using what is being produced).

2. a Hot Water Heat Pump

Those are questions #1, so anyone any advice or comments??

I had a salesman in today, and i thought he said I would need a Solar Power System to generate 4 kw (he is getting a proper quote together).

I re-looked at the account I gave him to work off, and it says I am using just over over 37 kWh per day at $0.17130c total-ling $7.36 per day.

Problem is, the account tells me I am using kWh (? kilowatt hours) and the salesman is talking in Kilowatts, and I'm buggarxd if I can equate one to the other!!

So, question #2..... Can anyone work it out? Is he right with his 4kw system. I don't want too small a system, but neither do I want to bigger one.


As a side issue, I did a stupid thing.
A Pump threw a bearing or something, (12 months back) so I changed it over with a spare I had in the shed.
On investigation today, the broken one used .55kw and the spare uses 1.1kw, and has been doing so for a long time.
When they put in 3 phase for me 12 months back, they couldn't keep the hot water on the real cheap night tariff, and combine that with the new coldroom running 4-6hrs a week....well the cost has gone up a lot.
Gonna make some changes around here!!

Suppose I should point out, the power bill came in yesterday, I saw it and got a bit excited, and wife tells me its been like that for the past 12 months!!! BM!!

Cheers
Phillip

 

[metriccrescentwrench]

Re: Solar Power and Hot Water Heat Pump

I'm going to make some assumptions to get to a roundabout answer. The main thing is how many hours per day, on average, the solar system can generate it's rated output of 4 kw. That depends on a lot of things like average cloud cover and your lattitude. If your system would be able to generate at rated output an average of 9 hours per day, then you're talking 36 kwh (9 hours x 4 kw) per day of capacity. I'd think the guy selling you the system should be able to dig up all the exact information for your location.

 

[trendsetter240]

Re: Solar Power and Hot Water Heat Pump

Absolutely the most effective way to reduce your power bill is to conserve energy. Install energy efficient appliances, lighting and insulation in your home.

The cost benefit for installing a solar system is entirely dependent upon the cost of the solar system + instalation and the cost of your electricity. The time it takes to cover the cost of the solar system is always measured in years.

In Australia you have more hours of sunlight per year than someone like myself far in the northern hemisphere. Still, it will take years for the system to pay for itself.

A kWh is one thousand watts for one hour. So if the solar system puts out a peak power of 4kw then you may see 4kw for about 4 hours around noon on a sunny day and less in the morning and evening hours.

I'm not saying it's a bad idea, I think it's a great idea. It just takes more than installing solar panels to make a significant difference to your overall energy cost. You need to reduce your energy usage at the same time.

Think about how much money you will save by replacing that bearing with the proper one...then start looking at your other appliances and the savings will really add up.

Cheers

 

[gjm700]

Re: Solar Power and Hot Water Heat Pump

Hi Phil,
We installed a grid connect system some 6 years ago. Ours was to cover the large number of black outs we experienced. I aslo wanted a back up battery system that would provide +24hr back up. When the main supply fails, the switch over is undetectable. Computers, fax machines etc keep running.

We have a 5kv system. The system wasn't cheap, but serves our purpose well. Achieves every thing we wanted.

gary

 

[Kiwi Phil]

Re: Solar Power and Hot Water Heat Pump

Thank you for the replies.

Today I did a little more research.

metriccrescentwrench
checked that out. 4.5hr/day over yr of excellent sun, (but another 6-7 hrs reasonable in summer and less winter)

T/S240
Thanks. Yes, changing appliances is the 1st move

eg the mentioned pump, the pool pump, and the return pump, plus the electric hot water system. It is on peak rates all the time and because of my set-up, I can't change that.

I also look at my office...I have 7 different items that have lights running when they are turned off, so I wonder about a master which to turn everything off completely.
Got a problem with fridges. Got 3 big ones, none new. 2 are needed for storing seed in so I think I better look at their consumption too, and possible alternatives.

The Govt subsidizes an inspection by an electrician, and the supply of a gadget that identifies appliance usage, so will apply for that.

Hot water is an issue and I think my options are
1. solar with electric back up (which will be on peak rates)
2. solar with gas back-up
3. a hot water heat pump which will apparently be about 60% less run cost.
4. a gas calafont...the thing that lights up and heats water when you turn on the tap... no cylinder

Don't know what way to go.
Anyone using one of the above?

That's my 1st decision/move, but i will plan out the solar electricity now for later.
I know I have to go that way

gjm700

is yours a 5kv or 5kw system.
your batteries interest me....what have you done there.
do you put power back in to the grid. I was told you get paid 3x more than when you buy it from grid.

Out of interest, my annual bill is $2,800 and with a 13% increase coming??? over $3,100, and I live in the sub tropics!!

Cheers
Phillip

 

[marlboro180]

Re: Solar Power and Hot Water Heat Pump

Phillip,

I cannot speak to the PV side of things from personal experience, except that the Dept. of Energy here in the US has pushed the development of 10kw inverters at a reasonable cost. That component is really spendy....The reason for the push on that size of an inverter is that they seem to think that homes here in the US would need a solar (PV) system sized at about 10kw to keep things the way they are in the average home ( in terms of usage)

Conservation is the first place to start, as you well know Power strips are a good start.

On yer heat pump- I got nuthin...BUT-

I have a solar hot water system at my home , and so far I like it, though it still needs some tweaking. It heats not only domestic hot water, but also my radiant heat floors in a 2400 square foot home.( in a cold climate here in the winter)

On the roof- 6 AET Morningstar Panels- ( 192 square feet total)


In the crawlspace:

2 drainback tanks ( I can run the system at half capacity in the summer- thats all I need then, but then kick in the other half in fall for additional heating load)

In the mechanical room:

2 Eaglesun pump controllers

Munchkin natural gas boiler (modulating up to 50,000 btu) w/ domestic sidearm (for domestic hot water or house heat)

Superstor Ultra 119 gal heat exchange tank ( 2 coils)
Superstor Ultra 50 gal. domestic hot water tank
Caleffi domestic hot water mix valve

Taco 501 and 503 controllers ( to tie everything together)

I just checked this morning, my storage was at 138*, heated by the sun. I have seen it as high as 158*. But I would like to see more yet!

I would probably go with a pre packaged Caleffi hot water system in retrospect, but I got a lot of dough tied up in the system I already have-oh well.


Just a question - what kind of house power do you guy run there? Volts/ Hz?

I am sure you have some renewable resources over there, here is one from over here---

http://www.the-mrea.org/

Midwest Renewable Energy Association

 

[rbh]

Re: Solar Power and Hot Water Heat Pump

Trying to grasp the reason for the heat pump (you have green houses don't you????)
Here in the great white north, not really, it can get to 110F in the summer and minus 45F in the winter sometimes.
Most people have turned to geo thermal, trench down 6-8 foot and build a grid of poly pipe.
Since the ground stayes warmer at 6-8 foot than the air temprature in the winter, easier to bring the circulated glycoll up to house temp.
And the opposite in the summer in the summer for cooling.
As well a grid of black polly pipe encased in glass on the sunny side of the roof can "supposedly" produce steam in the summer and bring the water temp up 20f-40f +-from the outside temp in the winter.
How about wind to generate power or opperate your pumps??

 

[jlinder]

Re: Solar Power and Hot Water Heat Pump

Lots of great ideas about how to generate power but I wonder if the topic is concentrating too much on alternate ways to make power and not enough on ways to reduce usage.

I suspect there is a better bang to the buck in finding ways to reduce consumption.

Have you looked at where you are using the power?

For example, you mention a couple of large coolers. Have you looked into ways to reduce usage like wrapping them in insulation? (That may not be viable, but you get the idea)

What about lighting? Have you looked at LED lights? There are 12v LED lights that can reduce your power draw (over incandescent) by 80-90%. (Or at least that is the claim).

You get the idea.

 

[marlboro180]

Re: Solar Power and Hot Water Heat Pump

jlinder,

I agree with you on the conservation first, then alternative power/heat 2nd. That concept is one that will/ should be preached by any solar outfit out there. They usually do.

Hey Phil - Do you guys have a program like this? Basically, the local utility has trained energy auditors to take a look at your home, your bills, your mechanicals , you , and how you use it all together. A blower door test is in the evaluation as well. People can have a really efficient home, and then leave all 6 plasma TVs running, with the house A/C running at 64* while they are not at home!

http://www.energystar.gov/index.cfm?c=new_homes.hm_index

I personally have not had them out yet, but it is in the works. Friend is becoming an evaluator for the program, and I get a free energy audit!! She thinks mine is gonna rock.

 

[Kiwi Phil]

Re: Solar Power and Hot Water Heat Pump

a quick reply.

1. jlinder is dead right. Usage is the big factor.
I am going to book a Govt Funded Audit tomorrow. (pretty much what you talked of marlboro180, says I get $450 service and digital tester for $50).

2. rbh. reason I mentioned heat pump is one salesman is recommending I go that way, and I'm not so sure.
Funny you should mention geo-thermal. Can't find much about it, and i do have the area to do it. Will start searching.

3. marlboro180. That is a big system you have, but I can see the reasoning when I see your in WI. I think I only need 2 of those panels as I only need hot water for showers, and as I have said before, a cold night here is 7C, and we are well into winter and have not had a heater on yet (just close the windows and put socks on).

So I will get things rolling tomorrow.

Thanks for your suggestions...I will keep you posted....and if you have any more suggestions, please pass them on.

Thank you.

Cheers
Phillip

 

[rbh]

Re: Solar Power and Hot Water Heat Pump

I just had a look at our power bill because we also just had a rate increase, we are now up to $0.13410 per KWH, that is up from $0.126 per KWH two month ago and I believe $0.116 two years ago.
All lights are flourecent, we heat with a wood stove, although I wish we had a wood fired boiler (I refuse to use electric base board heaters)
Our hot water is electric as well as the cooking stove,
The nearest natural gas is 600 meters down the hill and it may be awhile before it gets this far up, as it took ten years to go the 2 km to were it is now.
As for the geo thermal on the heating side for you, I am not sure that it would work as it does not drop into the minus double digits.
I might try burying a large cistern to collect solar heated water in the day
(you will need to build the collecter) then at night draw it out of the cistern and circulate it to were it is needed (poor mans boiler system)
Rob
Just to add KWH= killowatt hours (1000 watts) so 10, 100 watt light bulbs) running for an hour = 1kwh
KV=killo volt (1000 volt AC), this would be a very lite delivery voltge.
here single phase delivery is around 14.400 kv and three phase is 25.000 and up.

 

[Lion hunter]

Re: Solar Power and Hot Water Heat Pump

Here is one idea for hot water heat that can be done very cheap and will meet most of a normal househols needs if bathing, washing ect is done during the daylight hours. I have a friend with this system and it works great.

On the sunniest side of the house build a concrete block structure. His was about 5' x 5' and maybe 3' deep.

He the coiled as much 1/2" 160psi polyethlyene pipe into it as he could and tapped into the hot water heater in coming line.

He attempted to put plexi glass over the block structure but it got so hot it would blow the lines. He ended up just putting the plexiglass on in the winter.

It was just him and his wife and the system met all their need and the hot water heater rarely had to kick on.

 

[marlboro180]

Re: Solar Power and Hot Water Heat Pump

Lion Hunter- I too have seen that type of setup- Not for me here when the temps outside go below freezing! As to his pipes bursting, I forget the exact numbers, but PEX is not that great at holding pressure when it is heated to those kind of extreme temps.One has to watch out for stagnation with that setup.
My supplier even has a chunk of show and tell Rehau PEX that blew up. Some cornhole hooked up a couple of hot water panels and ran PEX to it, through an attic. Flooded the house due to its autofill valve.

Phillip- Yeah my system is kinda large Some even think overkill, but the real dollars were in the tanks and controls. My panels were about $1,000 each But what the heck , I was going for it! 3 panels would have been fine for our demand if it was just for domestic water.

This is the pre-engineered system I was speaking of. http://www.google.com/products/cata...og_result&ct=result&resnum=4&ved=0CC8Q8wIwAw#
The shop where I got my stuff has one running, works great. Since it is pretty much a showpiece, they piped it into a Modine type water to air exchanger , and heat part of their warehouse with it. I have seen systems that basically stack another coil in the plenum of their furnace A/C unit, and use the heat there too. Something to consider if you have a forced air system currently.

How did your energy audit go? Or does it take a while to get the results back?

BTW-
I finally hit my high limits today! Granted , it is summer here. The little orange light made me happy- That means the control system is working ! YAY! (picture below)

 

[Lion hunter]

Re: Solar Power and Hot Water Heat Pump

Marlboro,
It wasn't Pex that he used. He had bought the pipe from Numex. It was black PE pipe. Not real sure how it may differ from pex but we use the PE 1.25" above ground for range projects for livestock and have never had an issue with it. We have even installed where it has over 200 psi of head and it held up well. This was in Southern AZ where it does get freezing but rarely real hard freezes

 

[Kiwi Phil]

Re: Solar Power and Hot Water Heat Pump

Thank you everybody for your replies. I went over them in detail.

Interesting $50 (subsidized) energy audit on Friday. The auditor was ok (Govt Employee) and you really had to push him for info. Had to answer dozens of Q's.

I was given a gadget, one half is in the mains meter box transmiting power useage to a reciever in the house, displaying the kw used, and cost per hour.

The idea is, if the house is running at 6cents per hour ...and you turn on the electic jug, it jumps, telling you useage and cost. So it is pretty much up to me to work out what items use what amount of power, and for me to work out the changes I need to make, which is ok. I can do that.

After a shower it jumped from 'cents', to $1.70, so the water heater is going, and probably a pump.
By playing with it, I will easily calculate cost for everything.

Immediately the biggest culprit is electric hot water at peak cost (19.4c per kwh), followed closely by a pool pump, and then oversized irrigation pumps.

My switchboard is not at the house, so I need another cable from it to the house to carry 'off-peak' power at 7.9c kwh (appliances must be hard-wired for this 60% savings), for my hot water, and pool pump, in the middle of the night, (which I will change to a modern silent type using 25% less power at the reduced rate).

I will change the irrigation pumps (from 1.1kw to .750 kw = 25% savings).
Got many items in the office, that even tho turned off, still consume. Will install a master switch I can actually 'get to'.
Repeat same with stereo..tv's etc.
Light bulbs been changed.

I will hunt around for new timers for my irrigation (I am a commercial grower).
I currently use the industrial drum type (not dial) with the slides you push left to engage, right to disengage, and the shortest run time is 15minutes, and my system has never need 15 minute run times.
I do need pumps to run twice per hr, and on current system they run 30 minutes out of 60mins, whereas 2 times at 6-8minute each run is plenty.

In the past, the problem with electronic timers is,
1. they are measured by number of start and stop times, and I need 20 of each.
2. they are time consuming to set; check; hard to read; stupid mini size buttons to 'press'; absolute time wasters!!.
3. when the battery for the memory backup fails, when the power goes off at a later date, you have to be on to it quickly...and you never are!!
4. they suffer from severe wear from when the pump starts up, shortening their life.

In general they are not as good as the mechanical ones I use.

Anyone use 'mechanical type' at work with less than 15 minute minimum run time??
If you do, I really need to know about them.

The local suppliers are hopeless....they don't want to be bothered.

Now to solar hot water.
If I get an extra cable to the house with the 'off-peak', that is going to make a big difference, and on my calculations that cost of power (? 1,200 kwh @ 7.9c = $95 yr) ...why am I bothering with:

1. A heat pump is going to cost me $1,490 after rebates, or
2. A Solar water heater with elec backup costing me $2,400 after rebates

So the biggest reward is reducing greenhouse gases at my expense.

Here is another question for you.

Has anyone done a ' retrofit'....installed just the solar water heater panels on their roof and plumbed then in to their existing hot water cylinder?

gjm700.
I will get back to you about your system. I first need to make conservation changes.
I think I have covered everything for the moment and thanks again for the assistance.

Cheers
Phillip

 

[jlinder]

Re: Solar Power and Hot Water Heat Pump

Kiwi Phil,

Don't completely understand your irrigation setup but it sounds like you have a good number of timers that do not give you the control you are looking for.

Have you thought about converting to an electronic master system that controls all them? I know this would add a lot of complexity and questions about reliability but it might also have a lot of advantages.

Consider that you appear to have extra charges based on peak usage. With a central system could you set it so that all your watering heads did not come on at once - staggering the load.

If you eliminate the possibiity of a peak load you might be able to have a smaller pump. If timed correctly (on head switches off just as the next switches on) it could run with less on-off cycles.

You might also be able to put in sensors to measure how dry the soil is and have the system adjust watering times accordingly.

I know this would be a big increase in complexity, and you would need a UPS to protect power outages, but considering all the alternatives you have been looking at it might bea viable alternative.

 

[marlboro180]

Re: Solar Power and Hot Water Heat Pump

Phillip,
Glad to see you are looking at the conservation side first. Seems like you can conserve a lot of power and water by going to a different timer and smaller irrigation pumps. I wish I could help from here on that end of things, , but you guys run on different power ( 230V, 50 Hz, yes?) than here. Here in the States, Intermatic makes some great controls, as does Rockwell. SOMEBODY has to make one that will suit your needs.

I will ask around here, as I know a man who makes nursery goods/ beds, seed sorters, greenhouses, automated watering systems, etc. who is really knowledgable. We are designing a solar bed heater for his greenhouses currently .

Are you sure you are right with those numbers for the hot water? Something seems a bit off to me, or did I miss somethin? You started out by saying that it was the biggest use, then later stated it was less than than 3% of your total load / cost for the year? Im confused.

Immediately the biggest culprit is electric hot water at peak cost (19.4c per kwh), followed closely by a pool pump, and then oversized irrigation pumps.

If I get an extra cable to the house with the 'off-peak', that is going to make a big difference, and on my calculations that cost of power (? 1,200 kwh @ 7.9c = $95 yr) .. :

In regards to just plumbing some panels into the system, this certainly can but done but it is not without its limitations. One of the biggest is stagnation, which arises when there is no where to dump the heat gained during the day. ( Think 200 feet of black garden hose laying in the sun all day, then use it to wash off your hands)
One has to factor in the high heat output of the panels, which can pop your T & P valves pretty quick if the pressure builds up too far. ( Boyles Law) That can be remedied by a simple aquastat (or a pump controller), a plate (or coil )heat exchanger , and a pump. Oh, and a drainback tank , and a hot water mix valve so you dont get scalded.

The flat panels will run at lower temps than the evacuated tubes, but the tubes will perform better on a cloudy day. My plate collectors (AET)stagnate at 200+ *,
and the evacuated tubes I have seen stagnate at well over 300*

I think when you get the math worked out, the cost may become less of a factor . I wish I had just 2400 into my system!

Edit- Phillip,

Is a switchboard some sort of control from your power company to monitor/ control your usage during peak/ off peak rate times and that is how you utilize the dual rates?


LionHunter- I know of what you speak. PE aint gonna hold up to those pressures with high temperatures either. My oversight that it was not PEX. We dont use PE for potable water in these here parts of the country.Otherwise, it is really handy material.

 

[Kiwi Phil]

Re: Solar Power and Hot Water Heat Pump

jlinder

I have a volume pump (around 300Lpm I think), on a 8,000L tank, pumping downhill thru 1.5" pipe, then out thru approx 1,200 4mm tubes (really small) that put water into plastic hydroponic channels.
At the end of the channel, the water is directed underground (in 3" stormwater pipe) to a 2,000L tank at the bottom of the hill, and when the float switch rises sufficiently, another pump cuts in and returns it to the 8,000L tank at the top of the hill...ready for another cycle.

I once used a electronic master system (12 station...or heads) (still on the wall in the pump shed, plus I have a brand new spare one in its box).
It certainly did everything you talk about, but it operated the stations/heads like this.
I had a pressure pump, pressure lines, 12v control cable u/ground to solaniods. So the electronic control sends 12v to solanoid, opening it, water goes thru, pressure drops, pump starts, system runs.
I used a little 50lpm pressure pump and it worked well. I got 2 big new ones in the she too. Plus all the gear.

I changed it for the current system. It is so much simpler and needs less degree filtration.
I burnt out pressure pump 3 times....debris catches behind a rubber disc thing and and it won't cut off when the solanoids close.

Tell you what tho. I have certainly given it a lot of thought since you raised the issue. If I can't find a better mechanical timer then maybe I go back to it.
Thinking about it keeps me awake at night!

m..180
Liked the photos
Very quick note as I am going to Rockwell (they are here) to see what they say. Will see how that pans out first.
We are 240v.
Your friend...I think the drum timer I use is a 'block' as in, I think they put in an alloy horrizontal rail and can mount these things side by side in a row, just like fuse blocks.
I will send a photo if need be.
Retro fitting solar water panels....plumber is meant to be here after 3 jobs ahead of me ...he did mention pump and controller etc. Will let you know.
I think that is why flat panels are used mainly here.
A switchboard is a tin weatherproof box mains power comes in to, your metres are mounted in, and power is fed out to your house.
The Metre Reader comes, opens the door, reads metre and goes.
All fuses are there. It is on the outside of the house.
Mine is on a pole down by the nursery.
My sparky (brother to plumber) is coming to put in another metre and cable to carry off-peak to the house.

So thanks everyone.
Things are progressing.
I will be back.

Cheers
Phillip
.

 

[Kiwi Phil]

Re: Solar Power and Hot Water Heat Pump

Update.

Plumber advice

1. Don't retro-fit a solar water panel to an electric hot water cylinder unless the cylinder is reasonably new.
Fitting valves, timers, controllers, etc can be done but not worth the cost. My current cylinder is 7yrs, so switch to night-rate power, and replace with a complete solar system when it fails.

2. Don't use the glass tube type solar system in this area. Climates to harsh.

3. If possible buy the stainless steel type tank for here.

Electrician

1. new overhead cables to house to carry the 2 cheap power rates (1 hot water, 1 pool pump) when he is free

2. change pool pump from old 750 to 500 (silent and same output)

3. got the new irrigation pump

4. half way thru selecting a timer in 1 minute increments (currently using a 15 min minimum cycle). Not easy. Big range of industrial digital available. Not expensive either.

So things are chugging along nicely.

Cheers
Phillip

 

[marlboro180]

Re: Solar Power and Hot Water Heat Pump

Sounds like you are getting good advise. Lets see those bills and usage go down!