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Asking for advice, heating system replacement
#1
Hi,

As I explained in my presentation I would like to replace my fuel-oil calefaction system for a battery calefaction system. Please be patience with me I'm a newbbie and an ignorant. Well the evil plan is to built several power walls in order to feed the system, I have 120m2 to heat in da house. I was thinking about a 14s100p system, 51.8v, 260Ah (13.5 kW/h probably this calculation is wrong). The batteries will be charged from the grid in the cheapest period, in the future from a pure solar system. The use of the calefaction is around 10-12h/d in winter time. I've saw that the consumption of the electric system is 9 kW/h, it means that I would need at least 10 x 14s100p to feed the beast for one day. For clarifications, I cannot connect the electrical calefaction system directly to the grid because all house electrical system would have to be changed, my system only supports 3.3kW/h, so the scheme would be batteries connected to the grid for charge and connected in an isolated system to the electrical calefaction.

All help is welcome

Thanks guys
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#2
I would use the battery power to supplement the fuel/oil heating of your house using most of the battery for lighting, cooking, laundry,computers with limited heating with a mini split system if the climate isn't too cold.
later floyd
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#3
(06-16-2020, 03:45 PM)elnaib Wrote: Hi,

As I explained in my presentation I would like to replace my fuel-oil calefaction system for a battery calefaction system. Please be patience with me I'm a newbbie and an ignorant. Well the evil plan is to built several power walls in order to feed the system, I have 120m2 to heat in da house. I was thinking about a 14s100p system, 51.8v, 260Ah (13.5 kW/h probably this calculation is wrong). The batteries will be charged from the grid in the cheapest period, in the future from a pure solar system. The use of the calefaction is around 10-12h/d in winter time. I've saw that the consumption of the electric system is 9 kW/h, it means that I would need at least 10 x 14s100p to feed the beast for one day. For clarifications, I cannot connect the electrical calefaction system directly to the grid because all house electrical system would have to be changed, my system only supports 3.3kW/h, so the scheme would be batteries connected to the grid for charge and connected in an isolated system to the electrical calefaction.

All help is welcome

Thanks guys
>14s100p system, 51.8v, 260Ah (13.5 kW/h probably this calculation is wrong).
You're exactly right.  My own system is 14s100p / 260ah@48v nominal - but I also use 52v for my calcs.

A 10 x 260ah@52v battery bank is around 135kwh.   A consumption of 9kwh * 12h = 108kwh.   This is 108/135 = 80% DOD / day.    80% DOD is pretty 'hefty' for a pure 'discharge over 12h each day'  and I'd (gently) suggest thinking more in terms of 60% DOD goal to greatly extend the battery bank life.   12 x would be 70%'ish DOD,  14 x would be 60%'ish DOD.

However, its not clear (to me from above) whether charge would overlap with discharge - so you wouldn't need an 80% DOD as during the overlap period - the power can go directly to consumption.    

Finally - charging 108kwh/day is a pretty hefty amount of current.   In a 12hr period that's 9,000w/hour = 240v@38a'ish AC/hr and 52v@173a'ish DC/hr.  My own system can do 52v@240a max from a 12.8kw PV array for 80kwh/day max  - so you'd need something like 17kw PV array in summer time to produce 105kwh for a day.  Maybe 60'ish panels.   Smile  
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#4
(06-16-2020, 08:14 PM)OffGridInTheCity Wrote:
(06-16-2020, 03:45 PM)elnaib Wrote: Hi,

As I explained in my presentation I would like to replace my fuel-oil calefaction system for a battery calefaction system. Please be patience with me I'm a newbbie and an ignorant. Well the evil plan is to built several power walls in order to feed the system, I have 120m2 to heat in da house. I was thinking about a 14s100p system, 51.8v, 260Ah (13.5 kW/h probably this calculation is wrong). The batteries will be charged from the grid in the cheapest period, in the future from a pure solar system. The use of the calefaction is around 10-12h/d in winter time. I've saw that the consumption of the electric system is 9 kW/h, it means that I would need at least 10 x 14s100p to feed the beast for one day. For clarifications, I cannot connect the electrical calefaction system directly to the grid because all house electrical system would have to be changed, my system only supports 3.3kW/h, so the scheme would be batteries connected to the grid for charge and connected in an isolated system to the electrical calefaction.

All help is welcome

Thanks guys
>14s100p system, 51.8v, 260Ah (13.5 kW/h probably this calculation is wrong).
You're exactly right.  My own system is 14s100p / 260ah@48v nominal - but I also use 52v for my calcs.

A 10 x 260ah@52v battery bank is around 135kwh.   A consumption of 9kwh * 12h = 108kwh.   This is 108/135 = 80% DOD / day.    80% DOD is pretty 'hefty' for a pure 'discharge over 12h each day'  and I'd (gently) suggest thinking more in terms of 60% DOD goal to greatly extend the battery bank life.   12 x would be 70%'ish DOD,  14 x would be 60%'ish DOD.

However, its not clear (to me from above) whether charge would overlap with discharge - so you wouldn't need an 80% DOD as during the overlap period - the power can go directly to consumption.    

Finally - charging 108kwh/day is a pretty hefty amount of current.   In a 12hr period that's 9,000w/hour = 240v@38a'ish AC/hr and 52v@173a'ish DC/hr.  My own system can do 52v@240a max from a 12.8kw PV array for 80kwh/day max  - so you'd need something like 17kw PV array in summer time to produce 105kwh for a day.  Maybe 60'ish panels.   Smile  
Hi,

Thank you both for replies.

Floyd I will consider your proposal, but the key here is to replace the calefaction since it is to expensive and contaminant.

OffGridInTheCity, thank you for your calulations but according to my own calculations you would need 9/10 kW/h only for feed the calefaction, so as example 400 W/h per panel, you would need 25 panels. Furthermore, in my country there is a rectriction for consumers solar intallations, the max is 10 kW/h, for more potency the installation is considered as industrial and cannot be instalated in a house.

Regarding the connection directly to the comsuption, at this moment is not possible since my electric instalation only support 3.3 kW/h and I cannot change now, because is more expensive, since in my country you paid taxes depending on the capacity of your instalation. So for this reason is to create an isolate system only to connect calefaction to bateries and bateries connected to grid for charging and to calefaction to feed.


Saludos
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#5
Problem is that those 3.3Kw input you got does not cover what you need over 24hours so you still need to add something extra on top like solar or what not.

Perhaps change the heater system instead to something more efficient? Pushing out that many kWh into heat is ALOT! I use roughly 100kWh of heating during winter where i live and it would be impossible to go directly to electricity. In my case if i switch i would go towards
1. High efficient system that have an efficiency on atleast 5:1. Where you put in 1 part and get 5 part heat out...
2. Isolate the house.


Both above is what i would start with.
Note that cycling a battery like you intend will kill it in a year or 2. Also note that you have alof of innefficiencys converting. Like going grid -> battery -> heater you loose 15% easy. So that adds up even more. Then calculate the ROI Smile

What is "calefaction" ? Heating? What type of heating? Electrical elements?
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#6
(06-17-2020, 12:24 PM)daromer Wrote: What is "calefaction" ? Heating? What type of heating? Electrical elements?

Yeah, I had to look it up as well. It's heating. I'm guessing it was a translation issue. Just chose the wrong word. And since he's using fuel-oil, I would assume it's a lot like a gas heater or boiler type setup.

Personally, I would recommend trying to do bulk heating using Solar and if in a good area Wind. Solar is not just electrical panels, but also thermal collectors as well. It's amazing how much heat can be collected inside of a big box painted black inside and has a clear front facing the sun. Even in the far north. I've seen people from the Switzerland heating their homes with these in the dead of winter w/o much issues.
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#7
Hi,

Thanks for the suggestions, it is obvious that I'm not an English native, and my English is not so good, sorry for that.
Yes, calefaction is heating, thanks to correct me.
My heating system is feeding by diesel (fuel-oil) that boils the water.

Daromer, could you tell me about your heating system?
Korishan, I will read about black boxes.

Saludos
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#8
>....so as example 400 W/h per panel, you would need 25 panels. 
True on paper but you're not going to get 100% from a PV array and 400w panels seem a bit 'large' to me for a good price point.    I'm operating an array of 45 panels @ 285w/panel (from ebay sales) and sharing that they generate 80kwh/day in Southern OR.   

>Regarding the connection directly to the comsuption, at this moment is not possible since my electric instalation only support 3.3 kW/h 
What I ment was that if you have 3.3kw/h charging the batteries at the same time you are drawing (discharging) 9kw/h, then you have a 5.7kw/h discharge 'net'.  So the DOD could be more about 5.7kw/h discharge rather than 9kw/h discharge.    It wasn't clear to me how much of the 3.3 kw/h could be used to charge - maybe at night when you don't need the power for living during the day.   This 'overlap' (and % of 3.3kw/h) of power going into the battery bank and power coming out would significantly affect DOD / size of battery you need.

**You don't say how much sq ft you need to heat/cool  or your climate characteristics....   but heat pump technology would likely help reduce your power needs.  I live in a moderate climate and installed a 4 ton whole house heat pump in March   So far energy usage is amazingly low - a real game changer.  
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#9
I heat My house with Wood as primary. It cost me 500usd per year in Wood and perhaps 5 days to prepare the Wood


In electricity this would have been 8000usd atleast!!!

I would need insylation to get it better but thats a massive cost and as Long as i feel to work with Wood its cheaper. In Summer i heat house with excess solar energy instead the days its needed.

You can check My YouTube.

Your last Choice is to purely heat with electric elements. Its just not worth it. Its better to use solar air heaters IF so. They are like 80% efficient comparing to solar electricity that are. 15-20%
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#10
Here's a google image search of what I'm referring to: passive solar heating panel air box

There are different types of these boxes.
- a passive heat box that air just blows through
- a fluid heating unit that then has the fluid pumped to a heat exchanger, like a radiator.
* this one has several designs as well. One of them uses vacuum tubes (this one gets "really" hot). Others use coils of copper
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