Solar panels and battery - any real world reccomendations?

alphaomega16 said:
Nice, going to have to work out whats what after roof gets measured up, ideally out of the 2 rows of 5/6/7 that difference companies said it would be nice if minimum was 2 rows of 6 could be fitted on south but I feel that may be pushing it and panels are cheap enough I may considering 1 row on north to compensate and to help during the shorter winter months. I know its not ideal placement but its a shame I don't have a larger roof, im trying to get it right first time with winter months in mind to get as much battery filled as possible with the space I got on roof.

If I could get 2x6 rows of 430 Jinko panels on south roof that would be fantastic but im not a very optimistic person and spending this much I really want to nail everything down first time.
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North facing panels are a waste of money. In the winter they get no sun as the sun rises in the south east and sets in the south west. At this time of year they do help, but you get plenty of output anyway. Maxing out on the south first, followed by East/west is the way to go, unless you a homesick Aussie.
 
I ran the numbers on my north west facing roof in Easy PV, whilst it wasn't great it wasn't terrible, and as its mostly cloudy in the winter, so lots of light diffusion, I do wonder if they'd contribute pretty well. It would be an interesting experiment if I had the time/spare cash.
 
I am looking at getting solar panels, have south facing garden. I did 10k kwh last year(do 20k miles a year in an EV) currently on octopus go. Would the standard 4kw system be worth it ?
 
highog said:
I am looking at getting solar panels, have south facing garden. I did 10k kwh last year(do 20k miles a year in an EV) currently on octopus go. Would the standard 4kw system be worth it ?
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solar system is cheap, its getting it fit that costs the ££ so I agree with Hippo, as much as you can comfortably spare now before down the line you decide you want more and getting the equipment purchased will be less than what you pay to get it put up alongside what you already have, not to mention an inverter upgrade to accommodate new system.

I don't have an overly large roof so want to get as much wattage out of my south roof as I can, rest will go on batteries.

I really REALLY hope but very much doubt that 2 rows of 7 panels could be fit on roof so I can get 14 430w panels fitted and then whatever I got left from £16-17k will be spent on batteries. Would have loved an extra few thousand though :(

One bad day and I can charge batteries up on cheapie 4h period during night :D

Great-home have a nice calculator for solar (not sure if direct link allowed) but if you google "solar payback calculator" it should be second link.
 
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Ron-ski said:
I ran the numbers on my north west facing roof in Easy PV, whilst it wasn't great it wasn't terrible, and as its mostly cloudy in the winter, so lots of light diffusion, I do wonder if they'd contribute pretty well. It would be an interesting experiment if I had the time/spare cash.
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I did some work on winter output.

Solar panels rely on ambient light but unlike the human eye they do not adjust well to lower levels of light, they just give up and go to bed.

Before we went for our solar expansion, I knew that our background use was about 300 watts. We also knew that the shortest days had a possible production range of 6 hours or less. The real killer was the low level of the sun which has the effect of reducing light levels. Higher rainfall and cloudier conditions do not help. We also knew that in December the solar output would average around 2% of the stated output of the panels on cloudy days. I looked at lots of scenarios, but in the end I decided to just max out on the panels on our south roof and east roof.

With the new panels (taking my total to 14.4kw) we could reasonably expect to generate a minimum of 250 watts for a quarter of the day in dull conditions. In December 2021 we produced 297kw and last December it jumped to 444kw. Over the last 2 Decembers we have had 38 days of less than 10kw/day. Highest output was 35.8 and lowest was 0.4kw. On good days we can charge up the batteries to last up to 2 days.

January figures were 508 and 596.

In February we had only 5 days where output was less than 10kw/day. Best day was 54kw, with an average of 29kw/day. The whole picture had changed.

We are lucky that we live on the south coast as the further north you live, the longer you will have with a peak angle of the sun of less than 20 degrees. Yesterday, when it was nice and sunny our eastern array was only producing 222 watts at 5pm (there is 4.8kw capacity). This is aout 5%. It was bright and sunny. Even a really bad angle of sunshine makes a big difference.
 
highog said:
I am looking at getting solar panels, have south facing garden. I did 10k kwh last year(do 20k miles a year in an EV) currently on octopus go. Would the standard 4kw system be worth it ?
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I'd say, max out the panels - but as you're doing fairly high miles in an EV - you only really need a battery to last up until your overnight charge period. As soon as your EV starts charging - any batteries you've got will be drained dry.

More is always going to be better to an extent, but it might be hard to quantify a ROI difference beyond covering your evening useage.
 
Bug One said:
I'd say, max out the panels - but as you're doing fairly high miles in an EV - you only really need a battery to last up until your overnight charge period. As soon as your EV starts charging - any batteries you've got will be drained dry.

More is always going to be better to an extent, but it might be hard to quantify a ROI difference beyond covering your evening useage.
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I'm confused, why would batteries be drained dry charging his EV?
Just set discharge to no for that time period...
 
@Peteronthesouthcoast December is always the worst month for me, 4 December last year was zero, and 31 December was 150Wh, but I only had 4kW then, whole month was 83.5 kWh, barely enough for four days.

We have a 50 kW system at work, on 4/12/22 it produced just 1.8 kWh, and on the 31 it was just 6.9 kWh, so even with a massive array you'd still struggle in December unless you had lots of storage.
 
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Dec will be the worst month on average in the UK since its the shortest daylight hours of any month.

I wouldn't aim any system at UK based on Nov-Feb. There are going to be truly terrible days in that period.

I agree on the panels aspect, within reason as many as possible, and in order of South, West, East (South for pure generation capacity, West because time of use tariffs are always going to be higher later in the day)
As long as you don't have a massive roof then the inverter upto around 6kwh (some are 8 but many are 3 phase from what I have seen) can take around 7kw of panels, or even more.

As ever the risks with solar are down to an ever changing position. Flux changed that this year, who knows next, Flux may suck, something else could be launched etc.
IMO buy a system that doesn't massively overproduce in spring/autumn and decent amounts of storage on top of that.
I think your going to see more price volatility hour to hour / day to day as the grid greens and storage allows you to take advantage of that.
 
Ron-ski said:
@Peteronthesouthcoast December is always the worst month for me, 4 December last year was zero, and 31 December was 150Wh, but I only had 4kW then, whole month was 83.5 kWh, barely enough for four days.

We have a 50 kW system at work, on 4/12/22 it produced just 1.8 kWh, and on the 31 it was just 6.9 kWh, so even with a massive array you'd still struggle in December unless you had lots of storage.
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We do not survive December. For the last 2 years we have been off grid from about the 21st January until 1st December. I had forecast that it would be a month or just over either side of the equinox. What I had forgotten is that going into December we have the batteries which start off full and gradually fade away to nothing and in January you have to build up the batteries again. This explains the 3 weeks before the equinox and month after.

Ultimately I did decide to buy 4 x 6.5kw of batteries, but with hindsight I should have stuck with only 3. That last one only captures an extra 50-75kw every year. It does enable us to charge the car overnight at 5 amps for free and I took the position that when the batteries start to hold less charge, the extra battery would come into its own. Still as long as you do not tell the wife, I should be able to live with the mistake.
 
For those that love the data is there a way to or has someone already set up an excel sheet for either automatic entry based on solar input if that is possible or manual data entry for how much your system has saved.

Say for example you have leccie rate, daily standing charge, power imported/exported along with daily usage etc etc or is that a bit much for a sheet.

I know a lot of folk love data so thought id ask :D
 
alphaomega16 said:
For those that love the data is there a way to or has someone already set up an excel sheet for either automatic entry based on solar input if that is possible or manual data entry for how much your system has saved.

Say for example you have leccie rate, daily standing charge, power imported/exported along with daily usage etc etc or is that a bit much for a sheet.

I know a lot of folk love data so thought id ask :D
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Yes….but mine is connected to a power bi graph. I didnt add standing charge….only export and usage data.
 
not yet... a lot of moving parts in the whole calculation, what with generation, export, battery based off peak shifting. Plus we added a plugin hybrid at roughly the same time as the solar install which has thrown our usage up a load, but defiantly want to have a break even countdown on my dashboard at some point! Currently working on a solcast prediction shading adjustment to try and make the forcasts a bit more accurate :)
 
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