Solar panels and battery - any real world reccomendations?

I currently use 220 - 240KWH a month elec is solar worth it for me or is my use too low?

If it is what sort of sized system my house is detached with no shade on the roof from trees or anything
 
The_One said:
I currently use 220 - 240KWH a month elec is solar worth it for me or is my use too low?

If it is what sort of sized system my house is detached with no shade on the roof from trees or anything
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The (relatively fixed) installation costs are significant part of the bill so if you are going to do it, the sensible approach is to just put as many panels on the roof as will fit.

EDIT: It's not too difficult to roughly measure up your house to see how many will fit with a bit of Pythagoras theory.
 
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Export is paying pretty well these days and potentially only getting better so I agree, if you have room, over-size it. Short term you can export more, longer term maybe you add a heat pump or an EV, and the panels will really have room to stretch their legs.
 
Ron-ski said:
That was quick, changed over and now on Flux. Just need to email my FITS payment provider and let them know I shouldn't be paid for the deemed 50% export.

My 50% deemed export was worth about £110 a year, so I need to export 440kWh at the day rate to cover that, even less at the peak rate, which should be easy come the summer months.

Scheduled charging is easy on the Victron system, there is no scheduled discharging, but it can be done, just need to work out how.
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Odd, I applied early last week and not heard anything and still on my old tariff.
 
Welshman said:
you registered your interest...now you need to apply and fill in all you details and accept the terms
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I did the application part where I supplied my export MPAN, MCS number and DNO letter (even though they already have all of those). Wonder if it's because I'm on Economy 7, took 2 months to switch across to that (and then they suddenly back dated my bills for that period and cost me £35 because I hadn't been optimising my usage for Economy 7), so maybe switching back is also slow.

Just tried again and it failed, maybe because I'd already done it once, may have to try calling them later to find out what's going on.
 
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Tavis75 said:
I did the application part where I supplied my export MPAN, MCS number and DNO letter (even though they already have all of those). Wonder if it's because I'm on Economy 7, took 2 months to switch across to that (and then they suddenly back dated my bills for that period and cost me £35 because I hadn't been optimising my usage for Economy 7), so maybe switching back is also slow.
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mine was done within the hour after filling the application in and adding all my details.....very odd
 
Oh, and suddenly my account has updated to "Getting set for Octopus Flux" maybe re-submitting the application did do something after all.
 
Welshman said:
Does anyone worry when theres strong 50/60mph winds about their panels and roof??? Its wild up here today and forecast for the next 8 hrs or so……
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Nope. Mine have been on my house roof since December 2015, and we've had a fair few storms since then, last year there was one with 80mph winds. If installed properly they should be fine, hopefully my garage ones will be fine as well.
 
Welshman said:
Does anyone worry when theres strong 50/60mph winds about their panels and roof??? Its wild up here today and forecast for the next 8 hrs or so……
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Given how they are bolted to the roof timbers, id probably start to get worried if my roof got ripped off :D
 
SBo said:
This is what I would do also in your situation. Good future proofing and will allow you to get the most out of your system and any batteries today or added in future.
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Zeeflyboy said:
Yeah not particularly undersized for the panels, but those batteries can happily support a 5kw output all by themselves… so you’d be leaving a potential 1.4kw of power untapped when the batteries are there to support the load.
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HungryHippos said:
Yeah maybe get a bigger inverter for internal, but you could forego the G99 at that level I think.

Limit the inverter to 3.6kW export whilst leaving you with an internal 5kW inverter capacity.
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So i've asked about this inverter situation and whether a bigger one should be used and got the following response:
"Re the inverter, we are advised when specifying inverter sizing that the system should be 120% of the inverter rating as the limited time the panels will see the full 4500W means that the system runs more efficiently at the lower rated inverter. It will of course clip the system at 3.6KW. If you would like me to quote for the next size up inverter 4.6KW the price is only an additional £60.

The larger inverter will give you a larger battery discharge current see spec sheet attached. And yes, we can submit export limitation documents to UKPN."


I then also asked about the battery and acting like a UPS as on the website for it, i'd seen this:

Uninterruptible AC Power Supply or UPS​

In many cases, a solar battery will not be able to provide you with back-up power in the event of a power cut. This is because it is designed to automatically shut down so no electricity is passed to the grid where workers could be electrocuted. The PureStorage II, however, has been designed with safety features which mean it can continue to provide you with power during an outage. When it detects a power outage it will automatically island itself from the grid when and the inverter which will automatically take over the supply to the AC Output connected loads. This happens so fast (less than 20 milliseconds) that electronic equipment such as computers will continue to operate without disruption.
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and got the following in response

"Re UPS power, this is a difficult subject but, in a nutshell, yes, the system can provide backup power. However, we normally install an RCD double socket beside the batteries which will become energised upon power failure. We don’t tend to run the UPS into the mains fuse board as to conform to UK Power regulations we must install an automatic change over switch. This disconnects you form the grid upon power failure, this is so that your battery system doesn’t kick in and try to supply the whole street. Or the poor electrician trying to work on the mains cable down the road.

The other issue is that trying to power the whole house upon the event of a power failure means that you must load shed, as the battery output for the 3.6KW is 13A and 4.6KW 20A meaning that you must disconnect ovens and hobs or showers, items with high current draw to prevent damage to the battery and inverter."


So that means no? Does anyone with systems able to ask what happens in yours when you have a power cut?
 
We have a couple of sockets that we can plug stuff into. But since we've barely had more than 2 short power cuts in 6 years I'm not that bothered to be honest.

If you get a lot then it might be worth considering, but I think you have to have quite a bit of extra work/paperwork to make sure you're isolated from the grid.

If the battery can only discharge at 3.6 then as suggested you won't be able to use the oven or the kettle and high draw appliances at the same time unless they can fit a cut off based on power draw.

I personally have UPses for important systems like the internet and so on which will keep it running 30+ mins. However if the power cut lasts longer than that then I'm happy to just accept it and chill out for a bit.
 
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That is true, power cuts here are very infrequent. For instance you see techies in the US talk about UPS all the time but i don't have one and never felt the need for one.
 
Wegason said:
So that means no? Does anyone with systems able to ask what happens in yours when you have a power cut?
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Mine carries on working, supplying the entire house, but then I have an inverter that can supply a constant 8kW and peak to a lot more, battery and temperature permitting. It was reassuringly expensive though. If I did ever overload it, then it will shut down.
 
Mine would just shut down. I can't really think of much that I couldn't live without for a few hours while the power is off.

We've got a reasonably sized camping battery with 240v on it, everyone's got phones and wireless hotspots. I've even got a battery powered coffee machine if we get really desperate. :p
 
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I'm just wiring to my inverter today and the AC Backup is going to get left unwired. I live 2 doors from our sub station and I can count on one hand the outages we have had lasting more than a few mins on one hand in the last 50 odd years.
 
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