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 1 
 on: January 25, 2021, 08:54:56 PM 
Started by dan_b - Last post by pdf27
Thanks, I did not realise it was quite as low as that.  Wouldn't it be better to just inject the hydrogen into the gas grid? Bit like the old coal gas of my youth.
Nope, the inefficient bit is turning electricity into hydrogen. Once you've got the hydrogen, turning it into electricity to run a motor is about as efficient as burning it in a gas boiler, but displaces significantly more emissions.

 2 
 on: January 25, 2021, 07:46:59 PM 
Started by dan_b - Last post by JohnS
Thanks, I did not realise it was quite as low as that.  Wouldn't it be better to just inject the hydrogen into the gas grid? Bit like the old coal gas of my youth.

John

 3 
 on: January 25, 2021, 07:26:01 PM 
Started by deanobeano - Last post by nowty
Thanks for that info Nowty!

I'm now resisting the urge to boil my kettle by direct hook up to the panels

So, it looks like I would need a Tigo for each of the three panels? (spec sheet says 500W max power)

Then take one of the existing strings (of 8 panels) and then join the new ones to it in series?

Oh, if I'm going to use an optimiser, does that mean I could use a different brand of panel? ie, they don't need to be very close to the existing ones for voltage etc as the Tigo will sort it out?


Yes, yes and yes.

I meant to add don't bother reading about the stuff about boiling a kettle ! hysteria

You basically have the three Tigo's in series with the existing string which maintains the current (amps) of the existing string so if the added panels fully shade, its no worse than before. Each new panel is connected in parallel with each Tigo and the Tigo adds a variable voltage to the string at the same current so you end up with a string at a higher voltage at the same current, therefore more power. You don't need to use the same brand or even size of panel as the Tigo takes care of any electrical mismatch.

The only issue is how the existing inverter's MPPT deals with the varying voltage but most work fine.

Obviously you need to be comfortable with working with 500v DC. If you isolate the string before doing any work on it, there should be no voltage to earth from the panels, so that helps safety enormously.

If you go down the road of a separate inverter then officially need to inform the DNO who will probably say no, unless its G100 complaint (guarantees less than 3.68kW export), etc.

 4 
 on: January 25, 2021, 07:14:57 PM 
Started by GavIsGone - Last post by kdmnx
As with all such questions the answer is “it depends”. As you’ve gathered stoves vary hugely and the nominal figures are useless at anything other than comparing small/medium/large of the same make/model. Many stoves are listed as 5kW even though they are more powerful because that skips the requirement for additional ventilation. A 5.8kW stove is therefore very rare (and possibly better avoided).

The truth is that available air for combustion varies dramatically from one property to another however that doesn’t make for simple regulations. So you must have a vent irrelevant of your actual need and it has to be one that cannot be closed. Siting of the vent is important. You don’t want to be sitting between the vent and the fire because you’ll get an icy breeze hitting you no-matter how roaring the fire.


 5 
 on: January 25, 2021, 06:33:49 PM 
Started by GavIsGone - Last post by GavIsGone
Hi all

I'll be having a 6kW wood stove installed soon. It's an old house, so we get the first 5kW for free and only need to provide air for the remaining 1kW. From what I've read, this needs to be 23mm x 23mm for square, or 26mm diameter if round. We don't want any large grill faces or anything like that. Would prefer it to be visually as unnoticeable as possible. Can't do anything with the window, as that's being replaced in the future.

So...

- Would it be best to do one hole to spec, or several little holes?
- Can anyone work out what size the little holes would need to be if doing a few? Or is that as simple as dividing 26 by the number of holes?
- My installer said it would be enough to just have the holes lined... Any ideas what's best to use?
- How to make the holes rodent mouse proof?

Also, I've read several times how random the nominal rating of stoves is... How 5kW stoves can be largely different in physical size, have different sized fire boxes and therefore different fuel loading capacities, have different ranges (the Arada Ecoburn is rated 1.5 - 9Kw, whereas the Clearview Pioneer is rated 1kW - 5kW)), and yet all be rated as nominal 5kW. And on top of that, how the testing of stoves is very artificial and easily manipulated to reach a desired rating. With all that in mind - and forgetting HETAS, regs, etc for a moment - how much real life need is there for an air vent with a 6kW stove installed? For the record, the stove is a Woodwarm Fireview 6kW (5.8kW nominal to be precise).

Many thanks

(PS - We'd love to have a direct air feed but for several reasons it's just not possible.)

 6 
 on: January 25, 2021, 05:39:57 PM 
Started by deanobeano - Last post by deanobeano
Thanks for that info Nowty!

I'm now resisting the urge to boil my kettle by direct hook up to the panels

So, it looks like I would need a Tigo for each of the three panels? (spec sheet says 500W max power)

Then take one of the existing strings (of 8 panels) and then join the new ones to it in series?

Oh, if I'm going to use an optimiser, does that mean I could use a different brand of panel? ie, they don't need to be very close to the existing ones for voltage etc as the Tigo will sort it out?


 7 
 on: January 25, 2021, 05:09:28 PM 
Started by Solarchaser - Last post by mbeast
As far as I am aware, you cannot update the parallel LUX LXP3600s locally.

Pop Canhao at LUX China canhao.chen@luxpowertek.com an email tonight and he'll be able to check your inverters and, if necessary, update their firmware remotely.

Make sure you list each serial number of your inverters. You can get them from the LUX monitoring app at http://server.luxpowertek.com/WManage/web/login

Good luck, Andy

mine are the parallel units, downloaded the firmware then connected locally but when you tap on upgrade firmware it ask for a password.
I've emailed canhao but it seems mine has a internal problem with the battery connection so another one I'm going to need to take off and replace with a reconditioned one  Sad  . both less than 2 years old as well.
Apparently, the firmware update available on the app is for parallel units.
I've no way of checking as our inverter isn't parallel.

 8 
 on: January 25, 2021, 04:44:39 PM 
Started by dan_b - Last post by nowty
Something like this,

https://theconversation.com/hydrogen-cars-wont-overtake-electric-vehicles-because-theyre-hampered-by-the-laws-of-science-139899




 9 
 on: January 25, 2021, 04:16:29 PM 
Started by dan_b - Last post by M
I think there's a great chart somewhere breaking down all the losses and efficiencies, but basically 100% at the generation source gives approx 75% at the wheels for a BEV, and approx 25% for a HFCV. So you get roughly 3x the miles from a BEV v's a HFCV for a given amount of generation.

The benefits of hydrogen are really in very large storage volumes, taking advantage of cheap leccy left over after batteries and other more efficient forms of storage have been maxed out. Also H2 (in one form or another (such as ammonia)) is a more compact fuel for long distance ships, planes and so on, where batteries may not be a solution.

Cost wise, it comes back to the use of excess leccy being cheap. The main cost of producing H2 is the leccy, about 75% (I think), so H2 gets cheaper as leccy gets cheaper, but of course BEV's get cheaper as leccy gets cheaper, so it's excess - excess generation that is the key.

For road transport I just don't see it. The cost of rolling out a H2 charging infrastructure would be enormous, and given the need for 3x the generation to meet road uses, you have to wonder where all that excess - excess generation will come from.


Edit - This may be full of holes, but I once worked out that the UK car fleet would need about 17% more leccy gross if it went full BEV. At a rough guess perhaps 10% net after allowing for savings from the refining of the petrol diesel, and the savings from transportation, distribution, pumping etc. So 10%+

If I'm close to right, then HFCV's would need around 3x that, so about 51% gross, and 44% net if we remove the same 7% saving (seriously into speculative guesswork now). So 44%+ or 4.4x as much generation.

 10 
 on: January 25, 2021, 04:11:26 PM 
Started by mikeseaman3000 - Last post by kdmnx
Forgot to add. I use the Victron Quattro 48/8000, there are some cheaper ones from Victron i.e. 48/5000 models, but much more expensive than others.

Happy to help you set it up, if you get one

Plus you need solar charge controller(s) in addition to the inverter/charger whereas other manufacturers offer all-in-one boxes. I'm not surprised you went for the Victron having been messed around, nor that your happy with it. A VERY nice bit of kit.

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