PV energy less expensive than natural gas.

[electrodacus]

My house is now fully heated with electricity from PV as it is the lowest cost option even when compared to natural gas.

Solution is simple and reliable as everything is solid state no flames or water pipes just PV panels connected to DMPPT450 then directly connected to in floor resistive heat elements (concrete floor acts as large thermal mass storage large enough to deal with a few cloudy days) and small part of the PV array is diverted to SBMS120 to charge a small 5kWh LiFePO4 battery that provide all electricity for the house.
Since house heating and electricity is provided 100% by solar PV house is considered a net zero energy house.

Total cost of the system around 15000USD and designed to last at least 30 years thus cost amortization for the house energy (heating and electricity no transportation) is 500USD/year  (15000USD/30years) so an average of 42USD/month for electricity and heating a small 65m² (700sqft) in Saskatchewan Canada (heating season here is about 7 months per year).

Any one can compete with this numbers ?

[fourtytwo42]

That's very impressive the more so you have worked out the amortization that many seem to ignore! I would be interested to know the peak installed panel power ?

You obviously also use energy saving measures as your electrical demand is below what many seem able to use, perhaps you do not have the apparently obligatory 60 inch TV in every room 

Have you taken into account the reduction in efficiency over the life of the panels and battery pack ?

[electrodacus]

That's very impressive the more so you have worked out the amortization that many seem to ignore! I would be interested to know the peak installed panel power ?

Amortization cost is of course the most important factor and yes to many seem to ignore this.
PV array peak installed power will be 10.14kWh (39x260W) and while I have all panels I only installed 33 at this time 8.58kW in order to test how it will perform in 30 years when panels degradation may be 15 to 20%
Yes house is energy efficient thermally insulated close to passive house standards and energy usage is low most of the electricity (about 60%) is used for electric cooking.
Average energy usage is around 120kWh as electricity of course it also end up 100% as heating no matter if energy is use for computers LED lights or refrigerator.
Total peak energy including heating gets around 1000kWh/month in January (coldest moth here with average temperature of just -16.7C)
Thermal storage 150kWh (currently just about 90kWh likely not quite sufficient for worst case scenario).
Last winter was the first test but DMPPT450 was not ready so a bit lower efficiency with panels directly connected to heating elements and then I ended up needing 2x 100kWh propane tanks (small 8kg propane tanks) in January so 20% backup was needed and less than one propane tank in February so less than 10% but I do not expect any backup to be needed this year with the working DMPPT450 as this should add at least 30% extra compared to PV directly connected to fixed heating elements.
The small 5kWh LiFePO4 battery pack is only needed to provide electrical energy over night as battery can be fully charged by the large PV array even in the worst overcast day as the LiFePO4 battery has priority over heating since heating has a much larger thermal storage good for many overcast days.
Cost amortization for PV panels is just 2 to 3 cent/kWh for LiFePO4 around 15 to 20 cent/kWh and for thermal storage can be as low as 1 cent/kWh thus it makes sense to have a large thermal storage followed by a large PV array and a small as possible LiFePO4.
My base load is very low just under 24W at night (it will likely increase a bit when heat recovery ventilation will work but it is still very insignificant for the 4.7kWh battery even after a 20% degradation that should be in 20 years as I measured a less than 1% degradation per year).

[kripton2035]

can you post some pictures of your PV installation ?
a 260W panel is about 1 square meter, so how do you fit 39m2 of panels on a 65m2 flat ?

[nfmax]

Less expensive than LPG, I think you mean, not less expensive than natural gas. Much more credible!

[BradC]

Less expensive than LPG, I think you mean, not less expensive than natural gas. Much more credible!

Depends on where you live.

[fourtytwo42]

concrete floor acts as large thermal mass storage large enough to deal with a few cloudy days
PV array peak installed power will be 10.14kWh (39x260W)

That's one hell of an amazing idea, beats storing energy in a hot water cylinder any day, you just added another "must have" to my next house Very interesting your comment about all that concrete storing enough to cope with several cloudy days, guess it must be fairly well insulated from the ground, I assume that bit was a self build ?
Lots of investment there and faith in your idea, well done you so you can sit back and reap the rewards
Trouble is at my age I don't have the 30 years payback left but definitely set the cogs churning

[nctnico]

concrete floor acts as large thermal mass storage large enough to deal with a few cloudy days

Did you test this? My experience with floor heating is that a concrete floor cools down pretty quick (even when insulated with about 10cm of styrofoam). After a few hours it will get cold. The heat conductivity and thermal capacity of concrete are low. I'm pretty sure you'll need energy storage either as hot water or battery to keep the temperature constant. Combining PV with a solar boiler could be a good idea.

Since house heating and electricity is provided 100% by solar PV house is considered a net zero energy house.

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

[f4eru]

Combining PV with a solar boiler could be a good idea.

Thermal solar is better than PV+heat pump boiler, from the efficiency side.
A combination of both is a good system IMHO.
The efficiency difference of max 20% is however not relevant when speaking about solar, as you increase the area to compensate, and you overdesign anyway.
A PV+heat pump boiler has advantages over thermal solar+PV that you can use the excess energy in the summer as electricity instead of wasting it, and the installation cost is lower with one less medium to route to the roof.

As usual, YMMV depending on eventual subsidies, local weather pattern and local prices.

Storage of thermal energy in the thermal inertia of a concrete floor works but is limited.

Say you have a 10-ton concrete floor, which can increase temperature only + 5°C. Don't burn your feet !
You store less energy in that 10-ton concrete floor than a 1 m³ water storage which can increase temperature 65°C (30 to 95°C)
Also, one giant drawback is that you don't control the release rate of that thermal storage.

Thermal inertia works, and is a fact in most buildings, but it will not really help that much on the long run, especially if you want a tightly controlled temperature.

Also, of course, the concrete floor needs to be well isolated to the sides of the building and to the ground under.
Those are requirements anyway for properly energy efficient modern buildings.

For the record, I have a near passive house, wood structure and concrete floors, with 10m² thermal solar + 1,3m³ water tank + a wood burner (very efficient and clean). No PV yet.

[coppice]

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

Windows are an inefficient way to get fresh air. If you use a heat exchanger to draw in fresh air and expel stale air you can recover quite a bit of the temperature difference between the two air streams. It can also be the basis for humidity control.

[nctnico]

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

Windows are an inefficient way to get fresh air. If you use a heat exchanger to draw in fresh air and expel stale air you can recover quite a bit of the temperature difference between the two air streams. It can also be the basis for humidity control.

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

[ahbushnell]

concrete floor acts as large thermal mass storage large enough to deal with a few cloudy days

Did you test this? My experience with floor heating is that a concrete floor cools down pretty quick (even when insulated with about 10cm of styrofoam). After a few hours it will get cold. The heat conductivity and thermal capacity of concrete are low. I'm pretty sure you'll need energy storage either as hot water or battery to keep the temperature constant. Combining PV with a solar boiler could be a good idea.

Since house heating and electricity is provided 100% by solar PV house is considered a net zero energy house.

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

In the US people use heat exchangers on the ventilation to recovery energy. 

[coppice]

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

Windows are an inefficient way to get fresh air. If you use a heat exchanger to draw in fresh air and expel stale air you can recover quite a bit of the temperature difference between the two air streams. It can also be the basis for humidity control.

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

You see heat exchangers used more in hot countries with huge air con bills, than in cold countries with huge heating bills, but they work fine. Maintenance is basically just cleaning out the dirty at reasonable intervals.

[Marco]

Thermal storage in concrete only really makes sense if you use high temperature, water has 4 times the so specific heat and even per volume it stores more. The concrete doesn't need a container, but the water doesn't need a heat exchanger and can't crack.

[nctnico]

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

Windows are an inefficient way to get fresh air. If you use a heat exchanger to draw in fresh air and expel stale air you can recover quite a bit of the temperature difference between the two air streams. It can also be the basis for humidity control.

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

You see heat exchangers used more in hot countries with huge air con bills, than in cold countries with huge heating bills, but they work fine. Maintenance is basically just cleaning out the dirty at reasonable intervals.

And the reason for that is moisture. Airconditioners make the air more dry and the outside of the building is warm. In colder climates the outside is cold and the inside is warm. The warm air inside can contain a lot of moisture so every cold spot is a place where you get condensation and a nice environment for bacteria to grow and wood to rot. This is a big problem which is hard to fix!

[coppice]

How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

Windows are an inefficient way to get fresh air. If you use a heat exchanger to draw in fresh air and expel stale air you can recover quite a bit of the temperature difference between the two air streams. It can also be the basis for humidity control.

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

You see heat exchangers used more in hot countries with huge air con bills, than in cold countries with huge heating bills, but they work fine. Maintenance is basically just cleaning out the dirty at reasonable intervals.

And the reason for that is moisture. Airconditioners make the air more dry and the outside of the building is warm. In colder climates the outside is cold and the inside is warm. The warm air inside can contain a lot of moisture so every cold spot is a place where you get condensation and a nice environment for bacteria to grow and wood to rot. This is a big problem which is hard to fix!

The main visible problem with moisture in cold climates is water running down the inside of the windows, but if the walls lack insulation the moisture on the walls is far more troublesome, as it promotes mould growth. Heat exchangers can help with this, as the more sophisticated ones provide a centralised point for controlling the humidity of the warm air. There is no all encompassing solution, though, as drying the warm air too much can lead to a lot of damage to wood and other materials which are moisture sensitive.

[f4eru]

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

Nope. Works reliably, maintenance time is less than the sum of the time for opening and closing the windows every day.
It's a requirement for a modern house in most climates with colder periods, where the aeration energy is huge.

[nctnico]

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

Nope. Works reliably, maintenance time is less than the sum of the time for opening and closing the windows every day.
It's a requirement for a modern house in most climates with colder periods, where the aeration energy is huge.

Then why is everybody I have talked to complaining about these systems not working as advertised and needing lots of care and maintenance? Recently a relative of mine had a new house build and the builder advised against getting such a ventilation system due to the problems with it. Getting solar panels to reach the 'climate requirements' was a much safer option.

[kripton2035]

Quote from: nctnico on Today at 19:39:26

Recently a relative of mine had a new house build and the builder advised against getting such a ventilation system due to the problems with it.

How many sellers today understand what they sell ...?
As soon as they had some problem with one thing (they did not install correctly because they did not know how to install properly) and voila, this is something you shouldnt buy...

[f4eru]

the problems with it

What kind of "problems" ?

[cdev]

That sounds really great.

I am guessing that the sky is clear most of the time there, year round?

(fairly dry climate, even if kind of far northward)

BTW, nctnico, I have an HRV (balanced) ventilation system. Its definitely worth the cost, I am sure its paid for itself many times over in savings on both AC and heat, and it improves comfort.

It saves money year round.

I cant think of what problems somebody would see with it, could you be a bit more specific?

Something is set up wrong if they have problems, most likely. You have to open it up every few months and clean it, which takes around half an hour, I usually scrub down the filters and once every six months or so I might wash out the aluminum heat exchanger core in the basement sink. But really, washing the filters is the main thing. They catch dust and clog up if they are not cleaned. They have to be cleaned, but its a very simple procedure, just some soap and a brush.

My house is now fully heated with electricity from PV as it is the lowest cost option even when compared to natural gas.

Solution is simple and reliable as everything is solid state no flames or water pipes just PV panels connected to DMPPT450 then directly connected to in floor resistive heat elements (concrete floor acts as large thermal mass storage large enough to deal with a few cloudy days) and small part of the PV array is diverted to SBMS120 to charge a small 5kWh LiFePO4 battery that provide all electricity for the house.
Since house heating and electricity is provided 100% by solar PV house is considered a net zero energy house.

Total cost of the system around 15000USD and designed to last at least 30 years thus cost amortization for the house energy (heating and electricity no transportation) is 500USD/year  (15000USD/30years) so an average of 42USD/month for electricity and heating a small 65m² (700sqft) in Saskatchewan Canada (heating season here is about 7 months per year).

Any one can compete with this numbers ?

[cdev]

Maybe I am not understanding what their expectations are or how they all fit together.

I don't have a PV system and my HRV runs off of 115 v AC, its basically a fancy dual fan with a heat exchanger and filters. It warms up incoming air in the winter and cools it in the summer.

Its laid out like an X with the two airflows basically going perpendicular to one another.

In theory. In practise these systems don't seem to work very well and need a lot of maintenance too.

Nope. Works reliably, maintenance time is less than the sum of the time for opening and closing the windows every day.
It's a requirement for a modern house in most climates with colder periods, where the aeration energy is huge.

Then why is everybody I have talked to complaining about these systems not working as advertised and needing lots of care and maintenance? Recently a relative of mine had a new house build and the builder advised against getting such a ventilation system due to the problems with it. Getting solar panels to reach the 'climate requirements' was a much safer option.

What are the 'climate requirements'?

I am pretty sure they are required in new homes in Canada because the materials used in new homes now are so laden with things like formaldehyde and chemicals of various kinds that they are unhealthy without ventilation.

[electrodacus]

Wow.  I did not expected so many replays in a short period of time. Not sure how I will answer all but I will try.

can you post some pictures of your PV installation ?
a 260W panel is about 1 square meter, so how do you fit 39m2 of panels on a 65m2 flat ?

One 260W PV panel has about 1.65m2 so yes 39 panels will require about 65m2 but my panels are not installed on the roof but ground mount.
There are two reasons to have them ground mount and that is tilt angle needed here for max gain in winter is about 65 to 70 degree and that is how they are installed and second is that is easier to clean them.

Did you test this? My experience with floor heating is that a concrete floor cools down pretty quick (even when insulated with about 10cm of styrofoam). After a few hours it will get cold. The heat conductivity and thermal capacity of concrete are low. I'm pretty sure you'll need energy storage either as hot water or battery to keep the temperature constant. Combining PV with a solar boiler could be a good idea.
How about ventilation? My house is also well insulated but I need to have a few windows open to keep the air breathable and get the moisture out. In practise there is a point of diminishing returns when it comes to insulation because a house needs to ventilated as well.

This floor is designed by me completely insulated from outside no thermal bridge to ground and is fairly thick with a total of 14m³ of concrete. Heating one cubic meter of concrete by one degree Celsius requires 0.58kWh of energy so I assumed a max temperature range of 12C (18C to 30C) and thus total usable storage capacity for my concrete floor is 14m³ x 12C x 0.58kWh = 97kWh
Currently this is all I have and is good for 4 to 5 overcast days but I will need slightly more so I will need to add a 1500 liter plastic storage tank that will have a working temperature range of 20C to 55C thus 35C delta and to heat 1 liter of water by 1 degree Celsius you need 1.16Wh so storage capacity for that will be 1500 x 35 x 1.16 = 61kWh thus I will have a total of 158kWh that will be perfect for worst case situation based on my house requirements and my climate.
As for ventilation as mention is a work in progress as I want a 24V heat recovery ventilation so I need to design and build that myself. Currently I open the windows and loss from that is not that large still a heat recovery ventilation is a worth while investment and no modern house should be without one.

Thermal solar is better than PV+heat pump boiler, from the efficiency side.
A combination of both is a good system IMHO.
The efficiency difference of max 20% is however not relevant when speaking about solar, as you increase the area to compensate, and you overdesign anyway.
A PV+heat pump boiler has advantages over thermal solar+PV that you can use the excess energy in the summer as electricity instead of wasting it, and the installation cost is lower with one less medium to route to the roof.

Thermal solar is more expensive than PV solar and best way for me to answer this is to link to my presentation see page 5
also see my replay above yours.
Heat pumps are not cost effective when talking about PV solar heating as they have a limited life and fairly high cost's.
 

Thermal storage in concrete only really makes sense if you use high temperature, water has 4 times the so specific heat and even per volume it stores more. The concrete doesn't need a container, but the water doesn't need a heat exchanger and can't crack.

Thermal storage in concrete costs nothing if the house is designed to take advantage of the structural concrete that is already needed as it is my case with the 14m³ concrete floor 30 tones that is also the house foundation (insulated slab on grade).
As mentioned above I will use a combination of both for a total of 158kWh of thermal storage capacity.

That sounds really great.
I am guessing that the sky is clear most of the time there, year round?
(fairly dry climate, even if kind of far northward)

Is fairly sunny here in winter but also extremely cold thus this same house may require as much as 2x more energy for heating that in a more temperate climate where is less sunny thus likely the same PV array will be needed.


For photos of the system you can check my google+ page

[cdev]

You can buy HRV cores by themselves. The core in my unit is made of aluminum structured in a particular manner to maximize the surface area between two independent air flows that go through it perpendicular to one another. Its cube shaped.

[electrodacus]

You can buy HRV cores by themselves. The core in my unit is made of aluminum structured in a particular manner to maximize the surface area between two independent air flows that go through it perpendicular to one another. Its cube shaped.

Thanks. I already got the the HRV core and is made of aluminium and even have the brushless squirrel cage fans, I just did not got around to design and build a box for them to install, as with the huge temperature deltas here it needs to be very well done.