Hybrid System Yes or No.

nigtomdaw · November 2007

Ive been living permanently off grid now for over a year. My renewable spec is as my signature SW3024E 1600w fixed array, 2100 ah battery bank at 24volts , but power generation will eventually within the following year rise to 4kw PV total and a 1kw wind turbine. So hopefully the generator will be switched off for good . The house I live in is made from concrete blocks and its not alot of fun chasing walls for wiring. To date the house is all 240v AC and downstairs is 70 % completed ie newly plastered and painted. However upstairs and one room downstairs have still to be completed ie insulation and plaster board and it would be easily possible to incorporate a 12 volt system in all bedrooms and also the main sun room downstairs and pantry store. The kitchen living room and dining room are complete !

My solar shed batteries inverter are all together 15 meters from my house and only a single AC cable connects them. When I originally designed my system I thought long and hard about a 12 volt system only, then a hybrid system and eventually decided right or wrong to go 24volt DC to 240v AC Inverter Battery system .

As weve progressed from basic to comfortable living Ive noticed that my wallwarts have been breeding quicker that a Spanish Field Rat ! :grr

Spanish mains sockets are unswitched like US I guess which I find annoying all UK sockets are switched ! So unpluging isnt happening as it should. We have a teenager and UK friends who try there best but forget ! I have trailing master slave strip sockets where appropiate like on the TV which automaticaly switches the Sat TV decoder DVD player on or off with the master TV .

Our curent wallwarts are

Radio Linked Internet Gateway Modem 24/7
Separate Radio Telephone/Internet Hub 24/7
3 x Different Mobile Phone Chargers
3 x 12v bedside light reading lamps tansformers
2 x 12v LPG gas detector 24/7 One is in kitchen which I can wire to dedicated 12v DC
Wireless router 24/7
External Hard Drive 24/7
3 x Cordless Phone 24/7 (2 normal 1x Skype)

Told you they breed quick sneaky little Bu**ers:p

I imagine leaving the PC stuff out of the mix I could use 12volts for all the phones, via automotive adaptors , bedside lighting simply castrate the wall warts, and also impliment secondary upstairs 12 volt LED lighting which Im becoming a fan of (leds that is)

My questions basically is it worth doing, if so what is the best way to impliment a sub 12 volt system in to my house I can still have the option of 240v leds and I could wire a timed (solar friendly daylight hours only AC circuit upstairs say 4 hours a day over solar noon which would keep the up stairs phones charged up ).
I dont really want a separate 12 volt battery in the house but I wont rule it out ! If I had a 12 volt house supply I would make more use of it Im sure !

If so then how to get say a 25 amp 12 volt energy efficient supply to my house from an established 24 volt system 15 meters away . Im happy for the topic to stray towards better solutions in any direction ! PS I already have 2 New Marine/RV based switched fuse panel boards purchased when I was going down the 12 volt front.

BB. · November 2007

Re: Hybrid System Yes or No.

Pretty much, you will have to prove to yourself whether or not switching to 12 VDC will save power ($$$--sorry, I don't have a Euro sign handy

) or not...

Basically, measure the AC wattage of each unit * hours per day and set this against your fuel/solar/wind costs.

Then do the same things measuring DC wattage * hours per day * any 12 volt converter losses (which may be better, the same, or worst than your 240 VAC inverter losses).

My humble feeling--I believe that the power you will save from using DC will be minimal because of additional converter and wiring losses. I believe that simply placing switched outlets on each load will save you more money and be cheaper to implement.

And you may get some additional savings by even switching your DVD and sat. receiver off when the the TV is on watching local programs.

One last place you may save energy is looking at your minimum loads that run 24x7 (phones, phone chargers, Internet connection)... It is possible that running a new, small, (example 150 watt) inverter for these loads will allow the large inverter to shut down at night and save its (typically) higher losses (and higher inefficiencies) at low power levels.

But to prove that--you might have to run a few experiments and an Excel spread sheet to check.

It is possible that you are now at high enough 24x7 usage, and have large enough solar/wind/battery capacity (after your next planned upgrade)--that "small" savings are swamped by your day to day average power usage.

-Bill

westbranch · November 2007

Re: Hybrid System Yes or No.

As Bill says, switches may be the cheapest and most effective way to reduce phantom loads.
Will the Spanish code allow switched outlets? or does it even apply to your location?
Do you have a location for a separate 12 v arrangement in/on the house itself? ie fuse panel/batt./CC/PV panel etc
Will it be easier to wire a separate system than a 'mains' voltage system? noting the concrete block construction mentioned.

cheers
Eric

nigtomdaw · November 2007

Re: Hybrid System Yes or No.

The main inverter has to be on 24/7 as I have a Samsung American Fridge Freezer with ice/water that has a 530 kwh per annum rating this is my major comsumer, no air con just ceiling fans and window shutters. It would be relatively easy to install a 12 volt system in the unrestored part of the house but this also needs 240 ac wiring mains sockets also. Just AC lighting upstairs at present. where I can easily use mains powered LEDs I can easily convert the bedside lighting back to AC that takes three warts out , so its looking like it maybe not worth the effort and just stay AC with wall warts ? Sat TV decoder is alway on with TV as we get UK free terrestial TV via this. We currently dont watch local TV.

niel · November 2007

Re: Hybrid System Yes or No.

i agree with bill that there won't be any advantage to running the 12v that i can see. it may be a good idea to allow that future provision for the 12v wires as that may change down the road. to what extent you go will be up to you as you don't want to tear apart that which you already had gotten finished.

BB. · November 2007

Re: Hybrid System Yes or No.

You will probably save more money switching wall warts (for example, a ww+LED lighting switched, vs 12 volts + LED direct).

The costs of wiring 12 VDC is not insignificant... And the amount of power you can send out via 12 volt wiring for any distance is quite small... (a 5 volt drop on your 240 VAC is nothing--a 5 volt drop on 12 volt line--almost nothing will work right).

Plus, for the same load, your 12 volt wiring will have to be much larger (1 amp at 240 VAC = 240 watts--1 amp at 12 vdc = 12 watts).

If you put your small 24x7 stuff in your battery shed; Internet Interface, wireless lan, misc. battery chargers, etc.--it could make some sense--but wiring to your home--probably not).

-Bill

Hybrid System Yes or No.

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