solar/renewable for the long run

spalpeen · 05-12-2022 7:37pm #1

Hi all,

I'm buying a house and looking to kit out it for the best deal in terms of fuel efficiency in the long run.

How effective are solar panels? I keep reading that they are expensive and not worth it, ie don't pay off their initial cost...does this change with a longer time horizon eg 30 years? What if I also buy an electric car, does that change the calculus?

crisco10 · 05-12-2022 7:42pm

..

yankinlk · 05-12-2022 7:54pm

In for the replies.

graememk · 05-12-2022 8:12pm

Yes. They are effective. As long as you don't over pay. (See quotes thread)

One of the few things you can buy that actually have a pay back!

A well priced install should have a payback of about 10 yrs. Provided electric rates don't rise even more.

My install had a payback of 8-9 yrs in 2021. And that was with a day rate of 14c/7c night, anything put into the car/immersion was costed at night rate.

Now my rate is 28day/8 night.

If rates don't change, next year it's gonna be 47 day/13.75 night.

the_amazing_raisin · 05-12-2022 8:35pm

https://www.boards.ie/discussion/2058274698/solar-renewable-for-the-long-run

I'm getting them in February and they should have paid for themselves in 5-8 years. I'll let you know how it goes but I'm guessing you want an answer sooner 😉

A lot of the stories about solar panels not paying for themselves are from the days when panels were expensive and energy was cheap

Now energy is horrendously expensive and panels are...cheaper than they were 🙂

Frankly it's hard for a well thought out system to not pay for itself within a few years these days. A badly thought out system on the other hand...

There's three main questions you'll need to answer, how much energy will my house consume? How much of that consumption can I reduce by improving efficiency? And how much of the remaining consumption can I meet with solar energy (called self consumption)?

The idea is that you want to maximise the amount of energy generated by your panels that is used by your house, and not sent to the grid. In almost all cases sending energy to the grid is a loss, even if you're being paid for it

An EV is a great way to improve your self consumption because you can install a charger which will detect when you're sending power to the grid and divert that into your car. A Zappi is a popular choice for that

I wouldn't buy an EV simply to increase the payoff of my solar panels, however I would buy one for the rock bottom running costs and because they're amazing to drive 😁

There are other ways to self consume, for example just timing your appliances to come on when your panels are generating lots of power.

Another device is a hot water diverter which will heat your hot water tank when there's excess solar power, so you don't have to heat it later

Probably the simplest option for self consumption are batteries. You store energy when you have excess solar and use it later. It takes the forward planning out of the equation but it does add a lot of cost to the system, especially if buying from the installer

Batteries can also get you around the problem of winter sun, or rather the lack of sunlight. The idea is you charge the battery at night when electricity is cheap and use it during the day instead of paying for expensive day rate electricity

So in summary, yes solar panels will eventually pay for themselves

How long will it take? It depends but you can get down to under 10 years with the right planning

yankinlk · 05-12-2022 8:54pm

https://www.boards.ie/discussion/comment/119961260#Comment_119961260

Excellent.

"There's three main questions you'll need to answer, how much energy will my house consume? How much of that consumption can I reduce by improving efficiency? And how much of the remaining consumption can I meet with solar energy (called self consumption)?" @the_amazing_raisin

If this isn't already in the FAQ it should be added.

yankinlk · 05-12-2022 8:56pm

Honestly the amount of people I talk to that don't bother doing any research and just want to get a quote for a system... Without understanding the basic principles above is unreal.

the_amazing_raisin · 05-12-2022 9:19pm

https://www.boards.ie/discussion/comment/119961373#Comment_119961373

100% agree

There's a mindset of "I use some electricity, I make some electricity, everything is good" among a lot of people

And then they go out to get a quote, decide it costs too much and give up straight away

https://www.boards.ie/discussion/comment/119961364#Comment_119961364

Thanks 😁

I think it's in there in various forms but maybe not in those 3 questions exactly

People really underestimate the power of understanding your consumption before they just jump in deciding to get solar, or deciding it isn't worth it

And looking at total energy consumption is worthwhile, not just electricity

For example in my house we're using nearly 11,000kWh of electricity per year, which is vastly more than the 3,500kWh or so the CRU considers average

People say my electricity bills must be horrendous, and I'll concede they aren't cheap. But that's also my entire energy usage, no gas, oil, diesel or petrol.

And because electricity prices get cheaper at night unlike all those other fuels it means it's possible to realise considerable savings. It does also mean that whatever solar I can generate has a bigger impact to my overall savings

If I've one other bit of advice for the OP it would be to not rush into getting solar panels, unless you're planning a deep retrofit which would probably take a year anyway

Get yourself an energy monitor and start measuring the actual electricity consumption of your house. That'll help you understand the size of system you need

spalpeen · 05-12-2022 10:53pm

https://www.boards.ie/discussion/comment/119961260#Comment_119961260

"There's three main questions you'll need to answer, how much energy will my house consume? How much of that consumption can I reduce by improving efficiency? And how much of the remaining consumption can I meet with solar energy (called self consumption)?

Thank you. As a result I have a couple of Qs.

Are solar panels expected to get cheaper and if so should I wait?
Is Ireland expected to see more sun in future? I understand we can expect higher temperatures but unsure if that translates to sunlight.
So in regard to establishing energy consumption it is recommended to get an energy monitor? And in regard to reducing energy usage by improving efficiency...that would be guided by results of energy monitor? And how is the final point solved, re how much of the remaining consumption can be met by solar energy...does this mean that solar is only good when there is an abundant amount of excess energy requirement to be met?

Sorry I know these are basic qs but my understanding is very basic

the_amazing_raisin · 05-12-2022 11:14pm

So to answer the first one, probably not in the short term. In fact they might get a bit more expensive

As you've probably guessed there's a lot of interest in solar at the moment and prices are rising accordingly. Why sell something for €10 when you can sell it for €20. On top of that the cost of materials is going up so there's some upward pressure on prices

That's not to say you should jump in now, more that there's no point in waiting for prices to shift unless you know there's a big drop coming. Personally I'd say the right time is when you have a decent idea of your requirements and the budget to purchase the system

For the second question, basically no we're not really going to see more sun. Climate change might remove some cloud cover, but we're still fighting geography and low solar irradiance in winter

For the third question, there's a whole bunch of ways you can figure out your consumption. An energy monitor is a fairly cost effective option but regular meter readings are another or one of those plus in energy monitors for gauging a single appliance

You're correct that your decisions will be guided by these results, but also by the results of consumption of your other fuels, assuming there are any

For example, if your house is heated by gas then adding insulation obviously won't help electricity consumption but will bring down gas consumption

So it's good to get a handle on monitoring your consumption rates early and use the data from this to figure out your next steps

There's a fourth question which you should also seek to answer, and that is what is your goal for the system?

The simplest answer is reducing your energy costs but there's other motivations as well, such as reducing greenhouse gas emissions or having a degree of independence from the power grid

Your answer will kind of determine whether you're willing to endure some pretty steep expenses to accomplish your goals

slave1 · 06-12-2022 5:59pm

Don't think too deep on monitoring, start with a reading of your meter every morning for a few weeks and go from there

the_amazing_raisin · 06-12-2022 8:32pm

You can make some estimations of the house's consumption now, if you're buying it then it should have a BER rating and you should have information on the heating and cooking appliances

Unless you're running a hot tub or a load of power tools all the time (or using power tools in the hit tub, living on the edge 😂) then you can probably guess it to within a few hundred kWh

the_amazing_raisin · 06-12-2022 8:34pm

https://www.boards.ie/discussion/comment/119964629#Comment_119964629

Yeah I actually just used monthly meter readings to measure my usage and I only measure the EVs consumption to any high degree of accuracy

micks_address · 08-12-2022 4:29pm

https://www.boards.ie/discussion/comment/119965272#Comment_119965272

i just used my bill for usage.. i got my system in november.. the biggest win so far is charging the battery at night and using it during the day and timing the appliances to come on between 2 and 4am.. looks like im halving my bill already from 200 a month to 100 a month just doing that.. the excess solar helps on days you have it but for november/december it shrinks a lot.. id be quite frustrated with solar alone these months if i hadnt gotten the battery as id have little to no savings.. im on a smart meter which gives me 12 cents between 2am and 4 am.. its tight but i try and squeeze as much as possible into that..

solar/renewable for the long run

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