On the economics of off-grid energy...

I've paid, on average, around £30 a month for my electricity usage for the last decade, so I've never thought of it as a particularly significant expenditure - £30 a month is about the same as I spend on my broad band connection, about 50% less than what I spend on heating, about a third of what I spend on council tax, 25% of what it costs me to run my car, and a whopping 20 times less than I spend on mortgage payments.

TBH this has always irritated me a little - because one of the most fun things about my plan to go off grid is setting up a small solar electricity system - I mean, let's face it, off-grid solar energy systems are just cool, so I just kind of wish the cost of buying electricity from the grid was a little more expensive, so my relative savings could be better, compared to other aspects of off-grid living.

Having said that, if you look at things over a 10 year period, then a small'solar, off-grid electricity system does offer significant savings in the long term, even if you factor in a couple of new batteries along the way.

My Covid-impacted limited transitioning budget that I can only afford a very small scale system, the kind that's going to allow me to run mobile technology, and definitely not a washing machine!

How much will a small scale solar set up cost me?


Given that the plan is Portugal, where it's reasonably sunny, I figure I can get away with a 100 watt solar panel system, at least initially - that should be enough to power lap top, tablet, phone, lights, radio, and recharge some batteries for a few electric tools, as long as I'm careful.

Now I've already got a 100 Watt solar panel system - that cost me £220 (a bit pricey because it's easily portable, but I wanted low hassle at the time).

If I need to double up to a 200 Watt system, I can pick up another 100 Watt panel and connectors for just < £100, so that's somewhere between £220 - £320 total cost for the panels, and these should last me a good decade at least.

I've also already got a 1000 Watt inverter (hoping to run my 900 Watt Nutribullet), which cost £70.

I'm not sure what battery to buy, it's somewhere between the following two as 'entry level' batteries:

Total solar set up costs
  • Total min cost = £220 + £120 + £70 = £410
  • Total max cost = £320 + £240 + £70 = £630
  • Total max cost with a couple of extra batteries (cheap ones!) = £750

These are for me personally, and guesstimated. You could probably do this for less, you could certainly do it for more!

How long until this pays back compared to regular leccy?


Below I've compared my total min solar cost with my total max solar cost over 10 years with my full £360 a month leccy bill, and also a £10 a month cost, which discounts all of those appliances I can't realistically use when off-grid, and which account for most of my grid-use.

£30 monthly grid leccy, £10 monthly grid leccy, Cheap solar and Expensive solar .png

Even with my worst case scenario estimates - I end up breaking even after 6 years in 2026, and after 10 years I've saved almost £500 with the off grid system.

If I compare the 'max expenditure on solar (let's be pessimistic!) to the £30 a month grid expenditure, then I break even after one year, and make a saving of around £2500 over 10 years - not too shabby!

Which is the fairest comparison?


Maybe comparing the off-grid scenario with the full cost of my £30 a month leccy maybe isn't fair - at home I run a fridge freezer, electric cooker, regular T.V. and (and am I going to miss this....)..... a washing machine. I'll be giving all of these up to go off-grid.

If I wanted an off grid system that allowed to me run those heavier load appliances, I dread to think how much it would cost. I'd need a huge battery capacity for the freezer alone, and to be able to handle the spikes when I washed anything.

You could argue it's a fair comparison, because the off-grid system forces you into not being to use heavy load items, so that is part of the saving!

However, the discounted £10 a month figure, which discounts the electricity I use for such appliances that you can't realistically use with a small-scale off-grid system is certainly fair, I think.

But it's not just about the money..


I've always just wanted wanted wanted my own off-grid solar set up - this is about tech-fun, self-reliance and this slightly obsessive streak I've got with monitoring everything - I mean once I get this set up I can start obsessively counting how much wattage or amps, or whatever the units are (see I'm so knowledgeable!) for whatever appliance I'm using - it'll be techno-autist spread sheet heaven!

Postscript: is this off-grid leccy stuff even eco-friendly?


I haven't researched the environmental impact of solar panels and batteries, I'm a bit scared to, I've got this suspicion I'd discover they're terrible news for the planet, with all those nasty chemicals in the batteries?

Compared to a green-grid system, I/ we small scale low impact people might not be that low impact at all?

Or maybe that's not true with Lithium Ion, and maybe not all panels are created equal in terms of their environmental impact?

Posted Using LeoFinance



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Solar panels are still really expensive in the current times, I hope prices will drop in the future

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£220 - £320 is definitely reasonable especially since you said it'll last about one decade. In my country the cost of electricity is about 30$ monthly at least that's what I'm paying. In one year I'm paying about $360 which is definitely not cool and I feel you'll be getting quite a bargain since it's off-grid

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I think you can get wind-up radios, too?
Washing machines are increasingly eco-friendly. I love the one I've just got - it has a sensor and adjusts amount of water/temperature/duration of cycle/spin speed and duration to match the load, including being able to adjust for heavy items like towels. Not only can it put together the most eco-friendly programme for each load, because I can now economically and environmentally wash smaller loads, putting less strain on the bearings, the machine is likely to last for longer (although, of course, there are so many more electronic parts that can go wrong)!
Of course, your savings are an underestimate as, if you saved/invested those savings, there would be a compounding effect 😁
Great fun!

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Washing machines are amazing, one of my favourite ever talks is Hans Rosling's 'magic washing' machine talk, but it's more of a critique of the greens, well worth a watch!

I'd forgotten about the compounding, of course you're right!

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I recognize that calculating the payoff is useful. When I think through some of these things, however, I tend to think how much cash a decision frees up every month. For me, increasing my cash flow is a more useful factor.

In Economics, it is often said that a dollar today is worth two dollars tomorrow. I have often heard that mentioned when lecture turns to why you would sell a bond at a discount than keep it until maturity. I suppose in this case a solar system would be like a bond with a maturity date.

While 30 pounds is not a great deal to save, it's worth more today than the 30 pounds you will save in 2026. I think you can find better uses for 30 pounds today.

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(Edited)

Yes fair point, it's the same argument for not tying up money in property - However, I'm also into the grounded security you get with property and solar systems - I've already got enough money invested, this is like a hedge if all that goes tits up!

And a bit of fun learning about it all too!

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Same here. We are buying the house where we have been living the past few years. Once we get title, we're slapping on some solar. With Texas heat, our electric ranges from $100/mo in the "winter" to $270 in the summer. We stand to keep a good chunk of money with a solar system.

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is this off-grid leccy stuff even eco-friendly?

Here’s my gut feeling, depends on the source of energy on the grid. If it’s diesel or coal, then yes, if it’s a mix it depends and if it’s already high renewable no.

If you can go net metering (Without battery) vs off grid that is “greener”. If the utility can do DSM with your battery when your connected that is likely the greenest option.

This may be a good topic for me to look into more. Stay tuned

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Yes I don't think on grid is going to be an option, so batteries will be required, which I know is an issue!

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But not a "huge" issue really.

It really depends on the frame that you put around the systems when doing life cycle analysis. For example, if you focus ONLY on GHG emissions over 25yrs and you frame teh entire home, my guess is that the lifecycle cost of your solar system, with batteries will be MUCH MUCH less than cooking with gas.

That would include all the transportation costs, mining, manufacturing, etc.

With solar at least the USE will not contribute GHG, where with gas, even if the transportation, extraction, etc is less than solar/storage, you are releasing more for every pan of bacon.

This is not to "shame" the use of gas, but to put decisions in a framework.

I have gotten into arguments with engineers about the "subsidization" of wind energy where they "don't get that for coal". I would try to remind them that the roads and rail that transport the coal is not paid directly by the plant, the plant was built with taxpayer money, directly, etc.

Those subsidies are forgotten over the years. The role of subsidies is to steer society towards a set of values that are decided upon through elections and those that we elect.

Sorry for the ramble.

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Go for a 10kw system and sell it to the grid if they allow it and you are reasonably close.

Personally I would do 400w minimum. You are probably going to want a fan in the summer and a fridge, maybe power for an ebike.

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I'll build up to that! 400W that is! Yes, and you're possibly right about the fan!

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