Off-Grid Solar PV Setup

[kellys_eye]

Agree entirely on the self-sufficiency basis although those costs seem quite steep for what you're getting. As a comparison to the inverter-generator I have, I can power it for around 1000 hours (including the cost of the generator itself) for the same outlay as your solar setup based on todays fuel prices. Of course, the availability of fuel and/or its future cost is an unknown, in which case a solar setup is defo the way to go

I'm all for covering all bases though and that price isn't as bad as I expected - the solar panels themselves look to be a bargain - where did you get it and was it a deliverable item or did you have to get it yourself?

Being a total geek and nutcase hoarder of 'stuff' I have a pure sinewave inverter (3kW) lying around my shed so would use that as the basis for my system so I must really make some moves on sourcing a solar panel.

This thread is very incentivising!

[chrrris]

I'm all for covering all bases though and that price isn't as bad as I expected - the solar panels themselves look to be a bargain - where did you get it and was it a deliverable item or did you have to get it yourself?

The panel came from a company called Photonic Universe -- I'm pretty sure it said made in the UK on the box too, which pleased me, but I might be misremembering that. It was actually cheapest to order it via Amazon as they trade on there. The £299.99 included courier delivery which only took a day or two. It was this one that I ordered but I see they're now out of stock. They have 300W panels in stock though. Given that the panel is really the main event I have to say I'm really pleased with the performance of it so far -- seems capable of putting out a reasonable amount of power in overcast conditions which is a big concern for me, as the location of mine isn't ideal. It only really gets full sun from around midday, even in the height of summer so the fact it still does *something* in lower light conditions is important.

Being a total geek and nutcase hoarder of 'stuff' I have a pure sinewave inverter (3kW) lying around my shed so would use that as the basis for my system so I must really make some moves on sourcing a solar panel.

Nice... if it's a decent solidly-made one then that saves you a big chunk of the initial outlay. I'm not too sure about the inverter I have. It's been okay so far, but the reviews for it are mixed between "it's brilliant" through "it shuts down when I try to use my 900W angle grinder" to "blew up after 3 months. Avoid". So I'm none the wiser. I tried stressing it a bit earlier with the fridge, henry hoover, and my wife's 200W hair straighteners all running simultaneously, and it kept going but I noticed the fridge light was flickering so I'm not sure how "pure" the sine wave actually is under a heavy load and I don't own an oscilloscope to test it. Seems a bit shady though.

[kellys_eye]

for the purchase tip.

My inverter is old school - large inductors (transformers) and VERY heavy (50kg+) but really is true sinewave regardless of the load and experience tells me that the old stuff is invariably the best. It was originall yused by a local guy who's property is entirely off-grid and therefore uses solar/genset. I repaired that inverter for him a few years ago but he's recently fitted a larger unit and gave me the old one FOC.

Your inverter sounds very much like a 'stepped' output (albeit with filtering) as the increased load seems to be distorting the output. Not a huge problem but I wouldn't run sensitive electronics when the inverter is going full-belt. If you want reliability and a clean output then look at Victron stuff. I used to fit these in marine applications and they're as robust as hell not to mention 'clean'. Their 24V/1200W version is around £400.

[chrrris]

Your inverter sounds very much like a 'stepped' output (albeit with filtering) as the increased load seems to be distorting the output. Not a huge problem but I wouldn't run sensitive electronics when the inverter is going full-belt. If you want reliability and a clean output then look at Victron stuff. I used to fit these in marine applications and they're as robust as hell not to mention 'clean'. Their 24V/1200W version is around £400.

Ah, that would make sense, thanks -- as far as I can tell, it seems smooth enough at low loads, but rapidly goes all over the place past about 600W (or maybe it's when powering multiple devices causing the load to fluctuate). I think, like a cheap car, I'll just run it into the ground and buy a decent one that I can rely on to provide a clean output. I'll chalk this one up to part of the learning/research process.

Just seen that Victron stuff is available on Amazon, which is handy. And they do MPPT solar charge controllers with built-in Bluetooth for not much more than I paid for my Chinese-made controller+wifi box. Looks like they're well worth a look for anyone going down this path...

[chrrris]

Just watched an interesting video about solar panels on the EEVBlog channel on youtube. This guy had a 20% drop in the output of his 3kW-worth of panels, caused by... a tiny shadow being cast by the pole supporting his TV aerial! The shadow was so small he initially missed it on the stop-motion video he took of the panels.



The video is a bit long and wordy (although also very informative), but the long and the short of it is that these panels usually have 3 bypass diodes built into them. Each diode bypasses the current for two entire rows (of 12, in my case) individual solar cells. This is to protect against cell overheating if one cell is underperforming compared to its neighbours -- apparently it adds too much to the production costs to have separate bypasses for each cell, so the entire panel is split into 3 bypassable sections.

So a small bit of bird cr*p, or a small shadow, covering one part of a single cell can wipe out 1/3 of the entire production of a panel. I wish I knew this when setting up my panel, as part of it is sometimes shaded by a nearby church spire for a while when the sun is low in the sky, which I didn't think would be a big deal at the time. Mind you, there isn't a lot I can do about it without raising the panel up on a pole and annoying neighbours.

Its worth knowing for anyone planning such a system though.

[kellys_eye]

Mind you, there isn't a lot I can do about it

No? Shame Fred Dibna isn't still around - he'd have shifted the spire! What about 'time of year' - does this only happen over a certain period of weeks or is it going to be a permanent issue?

My BiL fitted 4kW on his house a number of years ago. He lives in the middle of Scotland (near Aviemore) and there's not a lot of light there any time, let alone during the long winter months yet, because he's a jammy git, he gets (iirc) some 54p/kW for all energy fed back into the grid - got the install done right at the peak of the subsidies!

Of course, for a SHTF situation the feed-in is irrelevant and it's all about the <Jeremy Clarkson voice> POOWWWER </Jeremey Clarkson voice> so placement seems to be everything. Then again, I'd be trying to offset any losses by having far more storage capacity than I would normally need which has the added benefit of less strain on the batteries (discharge).

I've just given away a 4.5kW genset - well, Mrs k_e volunteer-donated it without my permission but when I told her WHY I wanted to keep it (power tools on remote sites) she relented and has given me the ok to purchase a newer model which is going to be an IG version this time.

Now got 4 off 47kg bottle of LPG for my dual fuel genset. Building up to 8!

[chrrris]

No? Shame Fred Dibna isn't still around - he'd have shifted the spire! What about 'time of year' - does this only happen over a certain period of weeks or is it going to be a permanent issue?

The only real way around it (and, in an ideal world this is what I'd do...) is to put any panels on the pitched roof of the actual house, rather than the flat-roof extension. I'd fall foul of planning regs though -- for a so-called "standalone" (i.e. off-grid) solar system, no part of the installation can be any higher than 4 meters above ground level (round here, at least). And people round here are pretty hot on all that stuff too -- it wouldn't surprise me if neighbours have already been onto the local council checking my existing setup.

It's only going to be a problem from this time of year, up to (I'm guessing...) mid February, although it's going to get progressively worse has we head towards December. Once the sun is a bit higher it won't be a problem. It's a bit annoying though, as this is exactly the time of year I'd ideally like more free power.

Of course, for a SHTF situation the feed-in is irrelevant and it's all about the <Jeremy Clarkson voice> POOWWWER </Jeremey Clarkson voice> so placement seems to be everything. Then again, I'd be trying to offset any losses by having far more storage capacity than I would normally need which has the added benefit of less strain on the batteries (discharge).

I think one or two more batteries will be the next logical step for me. 3x120AH batteries = 4.32kWh of stored power (although, as I'm sure you already know, you're only really supposed to run the batteries down to no lower than 50% to preservethem, so only 2.16kWh usable). That's enough for a full 24h of fairly frivolous use, or a couple of days of sparse use. Mind you, it'll probably take about 3 days to build that 2.16kWh back up from my single 360W panel at this time of year.

I've just given away a 4.5kW genset - well, Mrs k_e volunteer-donated it without my permission but when I told her WHY I wanted to keep it (power tools on remote sites) she relented and has given me the ok to purchase a newer model which is going to be an IG version this time.

I have a half-baked plan to maybe try building a steam-powered generator at some point, using a car alternator or something. As I figure sourcing general combustible stuff (logs, coal, dried zombie corpses, etc) would be easier in a SHTF situation than sourcing petrol. I'll have to be a very good boy for quite a while longer before I get a pass to build a big steam engine in the back garden though (speaking of Fred Dibnah!)

Now got 4 off 47kg bottle of LPG for my dual fuel genset. Building up to 8!

Nice. Well that should certainly keep you going for a while!

[kellys_eye]

I have a half-baked plan to maybe try building a steam-powered generator at some point,

Well I have a half baked plan too..... so - two halves make a whole eh? I'm thinking 'rocket stove' and closed cycle steam turbine-type. Anyway, that's the 'exercise' for when the S does actually H the F and I have plently of time on my hands.

8 bottles of LPG will give me TWO WEEKS of 24/7 full-house power and considerably longer if/when I shut down a lot of unnecessary energy consuming devices - freezers in particular and a LOT more than that if I use the main genset only an hour or so a day.

The manufacturers of the genset claim (yet to test/prove) that it can deliver 2.5kW (this is half it's rated power output when running on LPG) at 0.79kg/hour so a 47kg bottle will last a fraction under 60 hours. 480 hours (8 bottles at 47kg) is twenty days!!! Running even 4 hours/day means 4 months!!!! Blimey, I could get a full year at 1 hour a day! Is there a 'smug' icon on here anywhere?

This is the genset I have https://www.machinemart.co.uk/p/champio ... generator/

I also took delivery of spares for the main genset last week - spare brushes and regulator. The rest I can 'spanner' my way through.

A lot of my backup is based on careful calculation of exactly what is needed and NO MORE. We can, theoretically, live electricity-free given the wood-fuel situation we have but my calculations allow for 'luxuries' such as lighting, gas boiler ignition and entertainment which, in our house, consume a maximum of 250W so are easily powered by the two suitcase 750W IG sets (one kept as spare). This feeds a separate circuit in the house (going in this week) feeding those 'red' 13A sockets strategically placed around.

I'm looking for an LPG conversion for these suitcase sets. I bought an LPG conversion for that 4.5kW set Mrs just 'gave away' but didn't actually fit it - wondering if I can adapt it to one of the suitcase gensets??? Hmmmmmm

[chrrris]

This is the genset I have https://www.machinemart.co.uk/p/champio ... generator/

I'm slightly jealous. That looks like a very nice bit of kit. And presumably one of the big benefits of propane is that it doesn't go off. If I had the space to store such a beast, and a decent amount of fuel, I think I'd be considering one of those too. My finger will be poised over the "Add to basket" button, ready to click if issues with the grid supply start to happen. Although I suspect, like with the solar stuff, costs will start to go up with rising demand if they haven't already...

[kellys_eye]

That looks like a very nice bit of kit.

I was apprehensive at first thought of purchasing it as it seems all 'sparkles and colour' - which it is - but I've given it the once-over (twice) and found it to be a robust construction, well built and should last a lifetime. The spares purchase was just me being anal.

The fact that it's propane was the big seller to me. I've considered all the options as far as fuel storage is concerned and haven't found any way to compensate for the degredation which means having to rely on a permanent, replaceable source of 'fresh' fuel. Ok, some additives work but not for as long as I feel might be necessary and availability of the additives themselves might prove dodgy - eventually.

So, with the prospect of LPG actually being a viable alternative to petrol/diesel in cars (in very common use in Russia due to the abundance therein and actually relatively easy to convert existing vehicles to it - a point I'm pushing whenever I can) I'm happy enough to both store it - perfectly legally too (petrol at home is under strict rules - not that that bothers me much) and I suspect LPG will, in time, become more common and a lot cheaper.

The only downside is the energy density - the genset 'only' puts out 5kW on LPG as opposed to 6.5kW on petrol but.... meh. Given I use 2 off 47kg annually for hot water and cooking I can also divert domestic supplies if I have to. I'd fit a large LPG tank if Calor didn't have an (almost) monopoly on them

So, if anyone is contemplating a genset I seriously suggest looking in to dual fuel devices. There are a number already available (see Machine Mart for a few) and conversion kits are pretty cheap (£45) for existing petrol gensets if yoiu have the nous to fit one.

[chrrris]

In news that I'm sure will come as no surprise at all to anyone with any experience of solar -- it turns out it's a bit sh*t in the winter (well, and the autumn as it currently is)! As the days get shorter and the sun gets lower in the sky, I've been seeing the electricity generated trending gradually downward, reaching a new low today of just 170Wh. This would only really be enough to light our house for maybe 4 hours - maybe a little bit longer with a conscious effort to switch unnecessary lights off, but still it's definitely not long enough in winter. Granted today was particularly grey and grimy here, but I would really need another panel of similar capacity to get away with moving the house lighting circuit over to solar without risking running out of juice.

I've been monitoring various appliances in the house. Our combi boiler, for example, (WB Greenstar 24i) draws around 90W of electricity with the heating on full-tilt. And one thing that has surprised me is the Kettle averaged only 167W per day over the course of a week with typical usage. So at least I'll be able to make a brew as usual in the event of a winter blackout (will just have to make sure I drink it during the day, or by candle-light!).

Biggest consumer of electricity in our house currently is the computer (with dual monitors), router, & associated gubbins at an 1.829kW/day, followed by the fridge/freezer at 873W/day, then the living room telly and Sky box at 830W/day. Obviously, the computer and telly are non-essentials.

[big-all]

a kettle with a cup off water will take perhaps 40-45 seconds mins at 2000w so about 4 cups worth in 3 mins 8cups in 6 and 80 cups an hour so at 2 unit at say 20p = 40p an hour divided by 80 cups = 0.5p per cup boiled or 25w per cup so your kettle being 167w would be perhaps 6 or 7 cups off tea at 20p a unit ??
at perhaps 14p a unit would be 0.3-0.35p per cup to boil but still around 167w ??

[chrrris]

a kettle with a cup off water will take perhaps 40-45 seconds mins at 2000w so about 4 cups worth in 3 mins 8cups in 6 and 80 cups an hour so at 2 unit at say 20p = 40p an hour divided by 80 cups = 0.5p per cup boiled or 25w per cup so your kettle being 167w would be perhaps 6 or 7 cups off tea at 20p a unit ??
at perhaps 14p a unit would be 0.3-0.35p per cup to boil but still around 167w ??

I'm not really sure what question you are asking. 167W over the course of a day is indeed enough for several cups of tea during that day, as I think your figures confirm. Unit prices are irrelevant since I am not paying for any of the energy generated.

[big-all]

a kettle with a cup off water will take perhaps 40-45 seconds mins at 2000w so about 4 cups worth in 3 mins 8cups in 6 and 80 cups an hour so at 2 unit at say 20p = 40p an hour divided by 80 cups = 0.5p per cup boiled or 25w per cup so your kettle being 167w would be perhaps 6 or 7 cups off tea at 20p a unit ??
at perhaps 14p a unit would be 0.3-0.35p per cup to boil but still around 167w ??

I'm not really sure what question you are asking. 167W over the course of a day is indeed enough for several cups of tea during that day, as I think your figures confirm. Unit prices are irrelevant since I am not paying for any of the energy generated.

just the way my brain work
it takes a number that can be analysed and computed and configured into a table that may or may not be useful and helpful and spews out results
most will probably see my ranting that will be read [and be pointless to most] but i enjoy the task of compiling a possibly useful chart as it comes naturally to my brain and if its helps a few understand its worth the great confusion it probably causes most as they can simply ignore my rantings and dismiss me as a silly old duffer
remember we need to keep the grey cells active and at nearing 68 i realise there is a perhaps 10-15% "fog" that i am trying to get the better off

[chrrris]

Fair enough!