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Dump the plumbing and use PV to heat water?
This simple technology (DC heating of water using PV panels)
has been tested for a few years by the government. BFRL: Solar Photovoltaic Hot Water System And now that PV panels are available for under one dollar a watt, http://ecorenovator.org/forum/solar-....html#post5341 it just might be cheaper to skip all the plumbing hardware and just wire some PV to a heating element in your HW tank.?. I'm trying to get some of those cheap panels to try my hand at making some hot water. I'm going to start with 4 panels, into a 75 ohm resistor, making about 240 watts of heat for my 76 gallon hot water storage. 240 watts per hour = 819 BTUh. Five hours of good sun, could mean 1.2 kWh or 4094 BTUh dumped into the tank daily. I'm not sure how much that would help keep the oil burner from coming on, but if the heat-loss is close to 819 BTUh, it could keep the tank coasting during the sunny part of the day at least. I like the idea of cutting out the middle-man inverter (and/or battery) losses. And the idea of just using a 75 ohm resistor and some PV panels is very attractive to the purist in me. :cool: Years ago, I had a good working solar hot water system working. 3 big Novan collectors on the roof, made lots of hot water! But, after about 10 years, the plumbing starting going. The city water supply eats copper. And loves tanks and heat exchangers. The system worked well for about 15 years and was removed after a few years of collecting dust. A new tank and exchanger was too costly and I knew we would be needing roof shingles again before too long. If my guess is right, a PV driven hot water system, could last 30 years and still be working. Plus, it's going to be very low maintenance, if the parts count is kept low. Less things to go wrong, the longer they last. :D |
What about efficiency?
Just the PV's are 10%-15% efficient, plus resistor efficiency. I'm guessing that solar hot water systems can be 30% efficient (BIG ?). On one hand, I'm an efficiency buff, on the other, there are other things to consider... |
The efficiency is in the long term cost, IF you can get the cheap panels.
An it appears the day of the cheap panel isn't here yet.. I just got off the phone with the dealer and it turns out that Solar Panels : Solar Panels Direct $1.74 per watt is pulling a bait-n-switch with their shipping cost. It was: $58.80 USD 4 $235.20 USD Shipping and handling $101.74 USD Total $336.94 USD And now, they want $240 for shipping. More than the price of the panels.. I think maybe I'll wait until they have $1-a-watt panels at Lowes.. |
Yikes, yeah... that'll get people excited over nothing. Too bad too.
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This is why when I was talking to a solar hot water installer about heat pump water heaters he got worried, 550 watts to run the heat pump, they claim with the other elements it's around 5kwh per day... seems kind of high so with those specs you would need over a kw of pv, but compared to the cost of solar hot water panels, pumps, plumbing, fluid... and they still recommend having a back up for those, this the back up would be a switch.
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A heat pump hot-water heater is the best way to go for my setup.
I can get hot water from my boiler during the winter months, but don't like the waste of running the boiler in the summer.. A heat pump hot-water heater would cool and dehumidify my basement during the summer. And, from what I've read, they don't use a lot of kWh, when compared to heating elements. What would be idea, is a 24 volt DC heat pump hot-water heater! That would work way better than PV into resistance.. But, it would cost much more and be more prone to breakdown. According to the government studies that I've skimmed, the break-even for resistance hot-water heaters is the $1-a-watt panel.. Without a low priced panel, it's just something that most folks would not go for. Except those guys who buy a new Prius with the built in solar roof.. ;) They have mandated PV hot water on new houses and large renovations, in many areas down in Australia. " Hot water systems A typical 1kW solar photovoltaic hot water system avoids around 1200-1500kWh of grid electricity per annum, contributing to around 20% of residential sector greenhouse gas emissions (The Nous Group 2007). The Federal Government is currently giving consideration to a proposal to impose a nationwide ban on electric hot water systems (HWS) in new housing in all States from 2010, and for replacement HWS from 2012. Some States have already introduced such a ban, with South Australia placing a ban on electric HWS for both new homes and replacement units in existing homes on 1 July 2008, although the bans are conditional. This ban does not however apply to homes in remote areas, multi-unit dwellings or a unit replacing one which services only a shed or pool. A ban on electric HWS in Queensland (implemented 2006) currently applies only to new homes and substantial alterations and additions. It will be extended to apply to replacement units from 2010. The ban will initially be voluntary for those without access to reticulated gas. The NSW Building Code places an effective ban on the use of electric HWS in new housing and for alterations and additions requiring planning approval. It is difficult to reach the BASIX planning requirements without installing a low emissions hot water system. " http://www.caf.gov.au/documents/Acce...PRSReport3.pdf I guess they are doing more than just studying PVHW Down Under :D |
Vacuum tube solar heat collectors can be as much as 80% efficient!
Solar Water Heaters: Solar Hot Water Heaters For Home, Commercial & Industrial Solar Water Heating They are used all over China, in great numbers. The latest designs AFAICT are a glass tube with a copper heatpipe inside and a (near) vacuum in between them. The top of the heatpipe has contact with the water in the header. http://www.solarpanelsplus.com/images/spp-30-corner.pnghttp://www.solarpanelsplus.com/image...-collector.png If one of the tubes is broken, it can be unplugged and replaced. |
If there is more efficient technology, I wonder why the Australian government is supporting PV HW ?
Maybe they think something with no moving parts will last longer.?. |
Xringer, I found an article on PV HW in Popular Science, February 1995, p.41.
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Yeah, that's Fanney & Dougherty, the guys who did most of the research for the USG.
Here's a list of their papers. BFRL: Solar Photovoltaic Hot Water System Besides getting PVWH field testing started, their big idea was Power Point Tracking. They even took out a patent on it. My current PVWH project idea does not use Power Point Tracking, but does use Sun Tracking, with an old TVRO dish mount. http://ecorenovator.org/forum/projec...r-project.html The plan is, to track the sun, so the panels harvest the peak power available and then feed that power into a fixed load. The fixed load would be pre-matched to the panels.. For now, I think keeping it simple is the best choice. However, in the coming months, I will be looking at Fanney & Dougherty's ideas about automatic load matching. If it can be done without undue complexity, I'll do it. For a hot-water assist heater, I'm thinking of 2 thin-film 54v panels in series. Kaneka Thin Film Solar Panel 110w For about 108 volts at 220 watts (750 BTUh), which might not be enough to notice.. :o But, I plan to pre-test the 220 watt idea, by plugging in a 250 watt heater (using AC power). http://ecorenovator.org/forum/applia...ad-heater.html If 250 watts doesn't help reduce oil consumption, then I will have to think about using a larger fixed PV array.. I have been tracking daily oil use by logging the AC power use of the oil burner and hope to install the heater pad this week. http://ecorenovator.org/forum/projec....html#post6105 Once the 250 Watt heater is installed, and spring is here (home heating off) I can log oil usage data that only reflects domestic hot water usage. Maybe one week on and one week off will tell me if 250 watts makes a difference. If I see it's working ok, early on, I'll switch to 5 hours a day (11am to 4pm) and see how that works. This spring, I plan to install more insulation and a new (fully functional) water mixer on the boiler. The old mixer is pretty useless and wastes a lot of energy. Honeywell-Sparco AM100C-US-1 - Honeywell-Sparco - 1/2" Sweat Union Mixing Valve The new mixer goes down to 80 degrees F, which might be okay in the summer time.. |
If your calcs are right, I say yes--4100btu/h x 5 =20500btu
I use 13500btu/day for hot water. I could use less. 1 shower, couple handwashes, kit.sink use, 1 person. Goes up when the honey is here, not much, it is totally up to her. I am gone 12-14 hrs/day, and 2 weekends a month. Work, you remember, right? hahaha I have a 50g elec. heater, 4500w limited to 2, 1 hour events a day. It almost always cuts out before 1/2hr run time. Set for am/pm, I use right after the on cycle, always enough. Over-ride is a pushbutton, you know, when the guests are wasting your hard work. I am limited to elec(.085kwh) or LPG($3 gal.). LPG at 100% eff. (not possible) would cost more, and the hardware even more yet. Thats stupid. I am all ears about your project. |
I'm starting the 250 watt heater smoke test today.
It's installed on the boiler and all should be running 24/7 for a week or two. http://ecorenovator.org/forum/applia....html#post6094 It seems stable at 246 watts (839.38 BTUh). I'll keep an eye on it tonight, just in case it over-heats the boiler.. :rolleyes: (Not likely). Both smoke alarms test ok. Anyways, the reason I'm wasting energy is to simulate the heating power I would get from a very small PV array. (If I every buy some panels). Once I see there that 839.38 BTUh is actually more than the heat loss and is actually enough to save a bit of oil, I'll switch the heater to a timer and only apply AC power for 5 hours a day.. And see how that works for me.. One of the things that got me interested in better insulation of my boiler, replacing the mixer and PV solar assist, was a post I read somewhere about just using the pilot light on a gas water heater. I was amazed that anyone could heat their hot water tank with just a little pilot light. Edit: Found it! Water heating using ONLY the pilot light - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com I'm planning an experiment as I type this.. I'm going to turn off the oil burner and observe the rate of loss in the boiler. (With the hot pad on). If I can keep my wife from using any hot water for a while, I can get some interesting data.. :) |
"If I can keep my wife from using any hot water for a while" ????????
Thats an easy fix, throw her the car keys and a credit card, you'll have all the time you need!!! Seriously, this is a good test. The Alpha/Beta/commisioning trials of anything are a challenge. I get the comm phase at work, not much fun sometimes. The home stuff is fun, and keeps you out of trouble. Best of luck to ya |
Turns out, I have seen the enemy and I am him.. After starting up the test,
I went to wash up and automatically turned on the hot water.. (And I know it would take 30+ seconds to get to the bathroom). So, I went back down to the basement and pulled down the Hot water cut-off.. :o The long range forecast is looking like we are going to need some heat during the next few weeks. But, not a lot. I should be able to cut the min-max temp of the boiler down 8 or 10 degrees and still have pretty good baseboard heat.. Next month, I'll be able to lower the average temperature of the boiler down to about 120 to 130 degrees F. I think that's when I'll really find out if 250 watts does anything.. |
Equilibrium
The boiler didn't drop or gain a degree between 1800 and 2200 hours.
The gauge stayed at 162 F and the temperature probe placed just under the top cover stayed at exactly 100F for the whole 4 hours. I once did an over-night loss check on the boiler and found it had a loss of between 2 and 3 degrees per hour. I'm not sure if that was before or after I did the last insulating job.. IMHO, without the 240-250 watt heater, the temperature would have dropped at least a few degrees in 4 hours. Equilibrium. So, this is good news. There is room for improvement. A couple of things can be done without incurring much cost. 1. Increase insulation. 2. When it gets warmer outside, lower the Aquastat setting to 130F max. 3. Install the new mixer when it comes in next week. (Ebay). The mixer will really help during the winter when the boiler is at 180F.. Once 1 & 2 are done, I suspect there will be a net heat gain, if the heating pad is left on 24/7. But, that gain will be canceled out or go negative, once I put the heating pad on a 5 (or 6) hour timer. The solar tracker mount seems to be seeing good sun starting at 11:00 (tree blockage) and starts losing it around 16:30-17:00. I'll have to take a new look at it now that we set the clocks ahead.. :confused: |
We're getting good sun on the tracking mount between 10:30AM & 4:30PM
I'm thinking that 6 hours of good PV power will do the trick. I retested the 250w heating pad on the boiler today and got some good results. Time: Main: Upper: 13:00 148F 110F 15:00 152F 128F At these lower boiler temps, It looks like a 2 deg-per-hour increase on the main gauge and a 9 deg-per-hour under the upper cover. During a sunny 6 hour day, (if no hot water was used) the main storage could possibly pick up 12 degrees, if I was using a 250w PV array into a resistive HW heater! I'm thinking that 240 to 300 watts of PV would be a good match to my boiler, since it might coast some into the evening hours, before the oil burner would want to kick in again.. All bets are off, if the dishwasher is used or someone takes a shower.. :o But, over-all I suspect there will be some reduction in oil use. Especially during very sunny days when there is minimal hot water use.. If I we had went on a road trip this weekend, (using zero hot water), that burner is going to keep on running when the loss builds up. It's going to cycle once or twice a day. Pay back? Break even? Not a concern with this project.. :D |
Been dreaming of some of the smaller PV panels for this hot water idea..
Two of these ($707 shipped) would fit the tracker with some room to spare.. 120w solar panel, solar module 120w * 36pcs of 156x156mm multicrystalline solar cells (made in USA) * Pmax: 120W * Vmp: 17.6V * Imp: 6.81A * Voc: 21.82V * Isc: 7.46A * Size: 58.27"x26.61"x1.97" * Weight: 28.3lbs * UL, TUV and CEC listed I'm just wondering what would be the best way to deliver the max amount of juice to the heating element in the boiler.?. I've been thinking about using a 12V load resistance (~0.6 ohms), driven by one of those BZ MPPT250HV 25A,12V Maximum Power Point Tracking (MPPT) PV Charge Controllers.. Solar Cell, Solar Panel, Solar PV, Solar Products, Charge Controllers, Solar Trackers - BZ MPPT250HV 25A,12V for Higher Input Voltage But instead of charging a battery, it would be trying to deliver max amps at 12 volts into a load.?. OR, just use the less complex plain resistive load. Comments please.. Thanks, Rich |
Unless you need to store the energy for later use I'd think just a plain 'ol resistive load would be most efficient.
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I'm in a similar situation, but my boiler burns propane. In the summer the only thing the boiler does is heat our hot water via an Amtrol boilermate system.
I like this idea you're working on. No moving parts or added plumbing is definitely worth something over efficiency. Using an mppt or buck-boost converter circuit is a great way to get the most out of your panels. I was thinking about trying to build a buck-boost converter to play with, maybe implement it into small scale wind power. That way power that is produce under light winds (below the voltage required to do whatever I intend it to do) can still be put to use. |
efficiency efficiency
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I think many people look at PV efficiency / payback etc. totally based on today's kWh cost from their power company. I need to compare the cost of BTUs I can put into hot-water (using PV), with my cost for home heating oil. That oil isn't real cheap these days. In my case, the BTUs contained in a gallon of oil is somewhat irrelevant, because of the large amount of BTUs my oil burner just shoots up the chimney, and just plain old heat loss. Right now, Diesel Fuel is $2.84 to $3.36 a gallon around here. Home heating oil will be very close to the same price. If the cost of PV was $800, that would be equal to about 260 gallons of oil. IIRC, my tank holds 275 gallons of oil.. I'll bet you are incurring significant loss heating summer-time hot water with a whole house heating system too.. ~~~ I'm not sure how much would be gained with power-point-tracking vs. just hooking up the best possible matching load. Perhaps, if it's not too costly, I can start off with just a plain resistive load and see how well it works.. I've pretty much sold myself on the idea of just running 240 watts of PV.. That would make it a bit easier to handle the power level and the hardware. |
you've got me thinking about trying this with my pv array. Mine is capable of 280w peak (when new), so maybe I could get better use of the power this way than feeding back into the grid with my 200 watt inverter like I do now. Hmmm, I'll have to do some calculating. The only cost for me to try, is some type of heating element. Heck, I might even have something that will work for surface mount already.
I need to price propane, we only fill once a year since we burn lots of wood, but my back problems are quickly changing that :mad:. As far as I know, My boiler doesn't try to maintain a set internal water temp when in standby. So it doesn't use the main burner unless a zone calls for it. There are times in warm weather when the gage is showing a pretty low water temp. The standing pilot probably keeps some heat in it :rolleyes:. |
280w = 955 BTUh
It sounds like your domestic hot-water doesn't come from your boiler.
You must have a gas hot-water heater. My original goal was to save some oil during the summer by increasing the time between burn cycles, by adding in some PV BTUs. (Maybe 240w ~ 819 BTUh). But, I've been thinking that a bit more-is-better with PV.. And maybe about 1200 to 1300 BTU of extra heat would provide a more substantial oil savings. I think maybe two high performance panels providing about 400w total might be the right stuff. And about all my tracking mount can safely carry. I'm guessing that any more PV-BTUs might over-heat the boiler on a good day. Going for more power would boost the cost up to the 1k range and make it a little harder to sell to the little woman.. :eek: |
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I'm not even sure what point I was trying to make earlier :rolleyes:. |
It's somewhat clear now. I'll bet the HW holding tank temperature sensor can issue a call for a burn,
somehow.. Even if indirectly. If you use a bunch of HW, the holding tank-zone is going to end up costing you fuel. If you could put some PV BTUs into the holding tank?? Stop it from issuing a call? If it's a small tank, maybe it wouldn't need many watts to keep it warmed up.. |
Waking up this old idea
I've been doing some hot water heating with PV for a while now..
http://ecorenovator.org/forum/solar-...r-heating.html http://ecorenovator.org/forum/geothe...html#post29717 Since the wattage required has always been the big question, I wanted to post the above links, to give PVDHW DIYers an idea of what's possible these days. Keep in mind, I'm using PV to supplement our A7 ASHP water heater. Recently, while using about 1kW of PV, the A7 isn't running at all. (Unless it gets really over-cast, it won't come on). From what I can tell right now, it seems that our household could get by using about 1,000 watts of PV (or power from the grid) for hot water. That's 3412 BTUh, or x6 hours ~ 6 kWh (20,472 BTUh per day). That's only $1.00 USD from the grid, at today's NStar rates. (16.61 cents per kWh). So, by running a GE water heater on 120vac using a Timex timer, http://ecorenovator.org/forum/introd...html#post25549 A low usage family could get by on $1 day for hot water.. :D So, if you have an extra 1kW of PV that's not being used, or you can afford to pay for 6kWh a day, to Mr. Grid, and don't mind waiting for a slow recovery time..?. It seems like using the grid at 120vac and a timer, is the most cost effective way to cut hot water cost. Using PV is going to cost more up front, but will be Greener.. :) |
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I'm not sure how it is that you are applying your solar PV power to your electric water heater when you are in resistance mode? Last time I tuned in, you had bolted a big power resistor to your old oil burner water reservoir. Are you still doing that? Reason I ask is that Elgo correctly pointed out that 'immersion resistance' heating was much more effective than 'surface contact resistance' heating. In my experiments in measuring the actual efficiency of surface contact resistance heating, I got an efficiency of about 66%, and I would assume that a power resistor bolted to a water reservoir would be much worse. Although I didn't test it, I would assume that immersion resistance heating would be closer to 100% efficient. So, are you using a resistance heating element that is actually in contact with the water you are heating, or not? -AC |
Nope, not trying to heat the oil burner anymore..
Since 5/1/2013 we are using the 13 ohm heating elements in the new GE water tank. It's got the A7 ASHP on top as the primary heat source. And using the two solar PV arrays to supplement the A7 on sunny days. http://i46.photobucket.com/albums/f1...psb7b37684.jpg We've only used about 1.2 kWh from the grid (in 6 days), since it's been mostly sunny. Not able to track the amount of PV power used, but I have been taking sample DC Amp readings. When it's nice out, we see about 1.0 kW of PV. The 500w tracker seems to stay at around 4 to 5.5 A most of the day.. While the fixed 800w array peaks up to around 7.4A in the middle of the day, but can drop down to 3 or 4 amps in the early afternoon.. Whilst, the 500w Tracker is maintaining a good 5 to 5.5.. The tracker is lower power, but provides that power for longer hours. I have some DC current sensors that I can use with the CAI board, that I may use to display real-time power.. Have no idea how to program for daily power logging.. :o I should be able to have the CAI send me emails when the temperature gets too high. Right now, it seems to be peaking out around 67C max. (152.6) Mostly it stays under 65C. (149F) Good for dish washing! Kills some germs. If we go boating for a few days, I'll have to leave everything unplugged, so the T&P doesn't open up and make a mess.. |
[QUOTE=Xringer;5360]This simple technology (DC heating of water using PV panels)
has been tested for a few years by the government. BFRL: Solar Photovoltaic Hot Water System it just might be cheaper to skip all the plumbing hardware and just wire some PV to a heating element in your HW tank.?. ----------------------------------------------------------------------------------- On a trip this spring on the park side of Gatlinburg, Tenn. I saw a Photovoltaic Array Ref: fire.nist.gov/bfrlpubs/build02/PDF/b02162.pdf That solar photovoltaic water heating system had been installed at the Great Smoky Mountains National Park (Sugarland) Visitors Center in the 90's. The solar was out behind the restroom/vending area. I had asked the Park Ranger about it and he pull out a reference info book, out of their office and told me a little about it. He said it was for hot water. That's what got me thinking about Solar Hot Water (Electric Resistance Water Heater) OK here's what I'm a thinking ………. "Using electric resistance heat, it takes 0.171 kWh to raise a gallon of 50 degree water to 120 degrees". Ref: http://http://www.greenbuildingadvis...r-thermal-deadSolar Thermal is Dead | GreenBuildingAdvisor.com And my PV System does 320-326 kWh per panel, per year. So I generate about 1 kWh per day per panel at this location. Lets say I build a stand alone system and use 4 panels and a inverter transfer device… 4/0.171 = 23.4 gallons of 120 degree hat water. (only two of us here) My cost would be around est. of $1250 for all the parts (I know a guy that knows a guy and so on) My savings would be 1460 x $0.0954 (kw rate now) = $139.28 per year (or (8.98) years for payback, but with the 30% tax credit it comes to 6.28 years) I plan on using the bottom element (electric resistance heat) for this on my two element electric water heater. This might be Pie in the Sky, as the costs will only go up the more I dig into this. But it's what I'm thinking for now. So far I plan on separate either 2,3,4 panels but will start with 2 and see how that would work. Can't tie in to the grid as that's AC (get paid base $0.10 plus $0.12 over per kw) and my contract is set, to open it up would lower the over rate to $0.09 or even lower. http://http://tackyted.com/solar/ (I'll have to read up on the code for this DC stuff) The new 2 panels would feed about 50 VDC down to a fused interface (working on it!) and then to the tanks lower heat element. The thermostat on the lower element on the tank would dictate the on/off. The upper element would run on the normal AC power, but set at a lower temp. As heat rises (well really cold falls) the upper element would stay off most of the time, cause the lower is keeping it warm. My big problem is finding a type of MPPT controler in the USA. I've seen the immerSUN & EMMA from the UK but these are for AC and I just want to do the DC. If y'all see any problems with my line of though or know of a control link please post, Thanks |
"my PV System does 320-326 kWh per panel, per year"..
So, you have a grid-tied system running right now? I didn't know they were into PV hotwater in the UK.. http://www.reuk.co.uk/Water-Heating-...s-Solar-PV.htm |
Share of my Solar PV outputs
Here's my Solar PV system
TackyTed - Solar At the bottom is a picture of what I produced my first year before I expanded. Here's all my output since upgrade …. Teddy-Denise 5kW Crossville,TN 4.998kW | Monthly My enphase inverters one per solar panel http://enlighten.enphaseenergy.com/p...tems/Wjgg11567 Here's some UK links for transfers to water heating, but AC and I need DC for a stand alone system I hope to build. PV Water Heating, Solar Hot Water Switch and Controller Supplier in Lincolnshire, UK | immerSUN Intelligent Solar PV Immersion Heater Switch - Use Surplus PV Power to Heat Water EnergyMyWay |
Now that's a nice system!
Since it's only for two people, why not use AC power right out of the enphase inverters? But, only use 120vac. That way, it will only draw 1.1 kW of power. (13 ohm element 9.23A) (Use a standard 120vac 15A circuit outlet). Only apply power to the heater when the sun is bright and your Enphase system is putting out at least 2kW. That way, your PV system will not send power out to the grid, but use it in real-time, heating your water. Heck, I tested with 120AC once and it worked pretty well. I might have used an X10 powehouse Appliance module. It can handle a 15A resistive load.. ($10 to $15 on Ebay). The hard part would be to build a fall-back device. If there is no sun, and the tank is starting to cool off, kick on the 1.1 kW anyways.. But limit it with a timer. Don't need hotwater at 2AM.. At that power level, won't cost much.. If the sun comes back out.. ;) My tank has the A7 ASHP to use when the sun isn't out. It's been rainy here, so the A7 ran yesterday and it's going to run again today. Right now the tank isn't really hot, but it's good enough for a couple of showers. At 13:00 the timer will send 120vac power to the A7, if the sun hasn't warmed it up, the A7 will turn on and run for an hour or two. The timer removes AC power at night. Since we are retired, we don't need real hot water in the early AM. If my Solar panels disappeared, or were hail damaged, I would use 120AC on a timer to run the A7. If the A7 died, I would use 120AC directly on the 13 ohm heating elements (via timer). At 1.1kW, I figure usage would be 4 to 5 kWh per day max. That's still not a lot. |
"That way, your PV system will not send power out to the grid, but use it in real-time, heating your water. "
Sorry but that would cost me $$$ I get $0.12 over the base rate of $0.10, thus $0.22 kw when I pump back into the grid. I pay about $0.10 when I use it from the grid. So far this year to date, my Electric Bill is $19.00 to date. Should be $0.00 or less at years end. |
I'm not up to speed on how grid tie works in difference places,
but I've heard a few people say, they sell kWhs for less than they pay for them on cloudy days. :( IIRC, there are places in Canada, where they pay you 2 or 3 times the price that users next door pay for kWh. I'm pretty sure that can't last. I guess they are trying to get everyone to install PV! In your shoes, I would just use a timer to heat water when the Enphase system was asleep, if I could do it at times where it wouldn't cause a big inconvenience. Using 1.1 kW instead of 4.5 kW (& 240vac) might not make much difference in the bill. Our tank isn't heated (with the A7) at all after 9PM. (timer turns on at 1PM and off at 9PM). Even if it's overcast for a couple of days, we don't have many problems. I think once, my wife had a lukewarm shower (after my long hot shower). :) Sometimes if I remember to, I'll bypass the timer during bad weather, and let the A7 run during the morning hours, if it needs to. That reminds me, I'm going to go take a shower now! |
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Geyser RO: Hot water with cooling as a byproduct! - YouTube |
Hey Guys ...
More info how it's (Solar) works for me. I have two meters (pic) http://tackyted.com/storage/solar/So...rMetersTed.jpg Really doesn't matter what I do at what time of day. Thankfully we don't have tiers or time of day rates. Bill (pic) http://tackyted.com/storage/solar/PowerMeterBilling.jpg Hope this helps y'all understand my Solar Power and Billing. I know this sounds so great and it is for me, but I got in 2010 on the pilot test program :-) :-) :-) That's now long gone. Note: the TVA serves 9 million people in the South East Now (new program) the TVA has only so much Solar KW per year open and it's first come first to get in. After that it's closed, so you have to wait till the next year to get in. This fills up in the first two months of the year. So if your in the TVA area think about this! You can't hook into the grid without that program. That's right no Solar for you (unless your into batteries) !!! So Yes I'm thankful I'm in for 10 years. So grab it (solar tie in) when you can. As it seems like part of the movement across sections of our country to SLOW SOLAR. Randy (the guy I got my self install solar from) (also a friend) wrote this about the TVA. TVA is killing the solar industry with 3 easy steps | and my post Life On The Plateau - Editoral - I'll take Coal Ash over Clean Renewable Power |
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Outlawing Net Metering is begging for outlaws to illegally back feed grid-tied PV systems with anything and everything they can purchase off the internet. (whether it is UL1741 compliant, or not). My utility has a PV incentive program that offers $2/W toward a PV system, IF you can get into their very limited waiting list, and IF you want to pay an installer to install the system. I chose to purchase my own system, and self-install it, skipping their incentive. |
Here in the state of MA, you could get a nice $1200 hybrid (ASHP+elements) hotwater heater for free.
But, to get the state rebate, you had to use a state approved installer.. I'm not sure, but I have a suspicion the install labor would end up being about $1199.99 |
Thanks for the thread, Xringer.
I do enjoy a novel idea :) I calculated some time ago that my shower consumes about 20 kW while running, so ~ 1.2 kWh of DC PV a day is good for about 3.6 minutes of shower time a day. Not bad, but I wonder if you have exhausted conservation ideas that are more efficient and less expensive ? 1. Low flow shower head. I switched out our old 2.5 gallon/min head with a 1.8 gallon/min. My wife *likes* the new one more, so I was a hero for a day, and cut my shower energy consumption by 28%. I paid about $25 if IIRC. Lower flow devices also are on the market but I have read complaints that the spray stings. ymmv. 2. If you have a shower that is often used on the second floor and some plumbing skills, check out drain heat exchangers. I think they cost under $400 and conserve about 50% of the hot water energy. Drain Water Heat Recovery | Department of Energy Here is a DIY http://www.youtube.com/watch?v=6btl1oYiPyY . I am not sure if the installation can be horizontal, or what the heat recovery is. Seems like the tubes should be sized to match the shower flow rate. 3. I am a wimp in the winter, but in the summer I turn off the water stream while I am soaping and shampooing. I think I keep the flow time to under 5 minutes. 4. If not done, well insulate your tank and pipes. I find that setting the hot water thermostat to about 120F is more than enough. 5. Wash clothes in cold water. ------ Lastly ... For your situation, comparing alternatives to oil heating is completely reasonable since that is what you have, but also consider whether spending your money on completely unrelated energy savings projects would give you a better return -- pollution and/or money wise. E.g., in our home I decided to replace our electric DWH heater. I considered ASHP, natural gas, condensing NG (high efficiency), and solar heating. In the end, I chose cheap tank natural gas and used the money saved to self-install windows. The windows cut my winter home heating bill by over half -- much more important than my DHW after conservation. In short, take a wide view of your home's energy use. Good luck, and thanks again for the interesting thread. |
Save trees cancel your daily newspaper!
No gas lines on my street. So, it's not on the selection list. :(
This month, the A7 is using 0.412 kWh per day from the grid. At 16.63 cents per kWh, that comes to 6.85 cents per day. ($2 per month). Considering we've been taking twice as many showers, I think that's pretty good. Solar PV DHW works! This week, at long last, we've finally canceled our daily newspaper delivery. Now saving $5 a week! ($261 per year, $21.75 per month). So, we now get our DHW for free, and have money left over for Pizza!! :rolleyes: |
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