Solar panels and battery - any real world reccomendations?

[Mercenary Keyboard Warrior]

Some general solar questions just for your opinion and to help my understanding. At the moment I only have a puny 2kW system with no batteries.



Current system:

2kW setup
8 x 260W panels Trina Honey TSM-PC05A (reading online Trina are a really good brand)
2.6kW Inverter

My general questions:

• Are solar panels hot swappable - in that I can buy some 500W ones and have an independent engineer swap them out right out? Unscrew old, plug in new? A quick fix to boost my power (even though my inverter might be too weak)
• I see some 500W-540W panels for £150 approx (https://www.zerohomebills.com/product/ja-solar-jam66s30-500-mr-500w-solar-panel/). Any opinions on these new 500w panels? First time i've seen them hit the market
• See the roof: Do you think that instead of replacing the 260w panels I should get a company to install 4/5 *more* 500w panels around the edge boosting my generation that way? Or see about swapping the original 8 and maybe adding more 500w. Perhaps squeezing 7 more panels around the sides to give a total of 7500w but this may be overkill
• Am I correct in thinking that I will lose my FIT if I change my system? I'm not that fussed because really I get something like £15 a quarter - it doesn', ate a lot and we use a lot in the day.
• If I heavily add to this system will I need to fill out one of those forms for going over 4kW or are those only if you intend on giving back to the grid? Part of me is considering just filling my own batteries and forgetting the grid
• My inverter would be way too small so the suggested upgrade would be to 5kW?

I will have a bit of a crack and some here before others step in as well

Those 500w panels look like the industrial ones which are a bit larger hence higher output. "normal" size panels are into the low 400w range now though.

How old are your old panels, might not be cost effective to replace them. Just leave as is.
Looks like you could get more panels up there though if you were to push the front ones almost to the edge.
Your inverter at 2.6 would limit you fairly quickly, unless you add another full system but then your back to maybe just rip out and reinstall from scratch.

Is it deffo "your" system and not owned by anyone else?

I assume all the space around due to leaving safe working space at height. I guess some installers would be willing to work closer to the edge but then you limit access should you need someone up there for another reason.

Cheapest might just be 8x replacement panels. Looks like there is capability for some diff panel sizing there on those frames. Wider but not longer looks ideal.
8x 400s is only 3.2kw so likely most of the time your not going to be inverter capped. Then just replace with a larger one when the old one eventually dies.

You can go battery thats AC coupled so you dont need to change inverter that way.

I think your on the edge of what makes sense here. If the system functions well it might be false economy to spend a lot more now when its working, your only going to see marginal gains.
Might be better to get some quotes in, work on options, if the best is to replace all then wait until your inverter dies and then do it.

I think ronski said your allowed some changes to Fit systems but your limited in return from fit to what the old system could produce.

 

[Bug One]

I think you'll benefit more from adding an AC coupled battery than any changes to your PV setup.

Higher power panels are mostly just bigger. Efficiency has increased a bit but it's mostly just a physical size increase per panel, giving a better price to performance ratio.

You could likely get more panels into that space if you shifted to a W configuration. Would be less efficient, but you'd get more peak energy at noon in summer. Doubt it would be worth it for the additional costs.

 

[HungryHippos]

Add battery and cheap overnight tariff could be good for general costs.

 

[reef]

Are they indoors?

If not, might be temperature related perhaps? Being cold reduces capacity, it varies but most won’t be operating at peak performance unless around 20-30 degrees (internally at least).

Yes, they're in the loft. The temperature of the batteries was about 13C rising to 16C when charging at 2.5kW this afternoon, so not too cold. Below 10C and the BMS slows charging rate.

I'm starting to think it's a reporting issue as they've gone from 12% to 62% today taking exactly 6kWh. That is about what I would expect from the 12.25kWh capacity.

I'm guessing its just the rubbish Fox software. The hardware itself is great. The batteries will throw out 5.4kW to the inverter to give 5kW to the house, so it's rare we use the grid when we have charge.

 

[HungryHippos]

13-16c is still a little cold I think for optimal performance.

 

[Wegason]

At 4.5kWp (and depending on panel orientation) it's not insanely under-sized, the systems that are like 6kWp+ with only 3.6kW inverters are way more tragic.

I'd gun for more panels if you can get them up though.

Previously told max i could get was 8 and this company reckons they can get 9 on. Doubt i can get more on due to my hipped roof.

 

[Wegason]

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.

Thanks, i've asked about doing this.

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.

Thanks. I've asked about this and see what they say.

 

[94JDH]

Some general solar questions just for your opinion and to help my understanding. At the moment I only have a puny 2kW system with no batteries.



Current system:

2kW setup
8 x 260W panels Trina Honey TSM-PC05A (reading online Trina are a really good brand)
2.6kW Inverter

My general questions:

• Are solar panels hot swappable - in that I can buy some 500W ones and have an independent engineer swap them out right out? Unscrew old, plug in new? A quick fix to boost my power (even though my inverter might be too weak)
• I see some 500W-540W panels for £150 approx (https://www.zerohomebills.com/product/ja-solar-jam66s30-500-mr-500w-solar-panel/). Any opinions on these new 500w panels? First time i've seen them hit the market
• See the roof: Do you think that instead of replacing the 260w panels I should get a company to install 4/5 *more* 500w panels around the edge boosting my generation that way? Or see about swapping the original 8 and maybe adding more 500w. Perhaps squeezing 7 more panels around the sides to give a total of 7500w but this may be overkill
• Am I correct in thinking that I will lose my FIT if I change my system? I'm not that fussed because really I get something like £15 a quarter - it doesn't generate a lot and we use a lot in the day.
• If I heavily add to this system will I need to fill out one of those forms for going over 3.6kW or are those only if you intend on giving back to the grid? Part of me is considering just filling my own batteries and forgetting the grid
• My inverter would be way too small so the suggested upgrade would be to 5kW?

Do you know what type of mounts they are, they look like Renusol but also a bit like Van Der Valk. They do usually have a range of fitments and you'd have to look at the appropriate data sheets.
Also, it's likely with the bigger panels 390W to 410W JA Solar for example, you might get a shadow on the panel behind and need opening up a bit more.

 

[Ron-ski]

@Vanilla As others have mentioned, the higher wattage panels are bigger, even circa 400w panels are bigger than my existing 250w panels installed in 2015. But it does look like you have some room to spare, so could potentially increase your array size by fitting new panels, and a new inverter, I'd also add a battery. I doubt you'll get more
than eight panels in total though, as room will need to be left for access and safety.

It always used to be that you couldn't alter a FITS system without losing the FITS payments, but my understanding now is that you can, and the payments would simply be pro-rata, so if you had a 2kw system and now have 4kw, the payment would be based on 50% of the generation. The install will highly likely have to be done by an MCS registered firm though increasing costs.

If you add to the system you will have to notify the DNO, under 3.6kw is just notification, for over that (G99) you need to apply before doing the work.

500w panels have been around for ages, you can even get 600w panels https://www.bimblesolar.com/600w-canadian-solar-panel

Don't touch Zero Home Bills, they are a scam website, you'll never get your goods, and struggle to get your money back, and you can't pay by credit card, strange that!

 

[Ron-ski]

Flux is live, just signed up.

 

[Freefaller]

Flux is live, just signed up.

I can't seem to see it. Did you contact them for it?

edit: found it, was easier to do on a laptop than my phone!

 

[Freefaller]

What's the best way to automate charging of the battery? Home assistant or the GE app. Obviously the flux profile during 2-5am and want to make sure I top up batteries if necessary during that time if they need it.

 

[Ron-ski]

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.

 

[HungryHippos]

It's Flux import only for now I think? I'm sticking on Go for now to keep costs down, even if the export rates are poor, I'm not really exporting anything at the moment.

What's the best way to automate charging of the battery? Home assistant or the GE app. Obviously the flux profile during 2-5am and want to make sure I top up batteries if necessary during that time if they need it.

Just go into the portal online and then into My Inverter => Settings. You can set a timed charge of the battery here.

I'm not 100% on this, but if I was on Flux I wonder if the best strategy is to:

Set charge to 100% from 02:00 - 16:00
Set discharge from 16:00 - 19:00

By doing this you will hold the battery at 100% all day, no matter the weather (excess generated solar will go to export to grid on a good day). Then export for the maximum payment you can get down from 100% to whatever it can export into that 3 hour window.

This seems sensible because you lower the battery cycles, it would be one complete cycle per day. Thoughts?

 

[Freefaller]

I guess it's a balance between export rate and import rate and usage. If the weather is good then the batteries will fill and there's no need to top up. I'll need to have a think about it.. problem is 4-7pm is prime cooking time so it's going to have to be a balance between grid usage and discharge.

 

[HungryHippos]

In my suggested method above it limits the cycles, if you alternatively charge to 100% between 02:00 - 05:00 and then allow solar top it up before exporting, there is ultimately more wear on the batteries for potential small gains in the daylight hours.

Also depends if you want to attempt to export as much as possible for the maximum payment you can get.

If you can use most of your generation efficiently with Go I think that will still win in the long term, though it's a bit more annoying to min/max it.

 

[Freefaller]

I can't be on Go

I like your method I just need to work it out based on our usage.

 

[b0rn2sk8]

The way to approach flux is going to be highly dependent on your own personal set up and consumption habits. To min max it you’d need to be looking at it daily which is going to be quite a hassle.

For me, I’d want to be holding onto about 5kwh of battery to see me though the evening peak and then just letting the solar and battery do it’s thing for the rest of the time. I’d be Charging the battery off peak in winter and not in summer.

 

[Welshman]

I'm all signed up now too.......

 

[SoliD]

It's Flux import only for now I think? I'm sticking on Go for now to keep costs down, even if the export rates are poor, I'm not really exporting anything at the moment.



Just go into the portal online and then into My Inverter => Settings. You can set a timed charge of the battery here.

I'm not 100% on this, but if I was on Flux I wonder if the best strategy is to:

Set charge to 100% from 02:00 - 16:00
Set discharge from 16:00 - 19:00

By doing this you will hold the battery at 100% all day, no matter the weather (excess generated solar will go to export to grid on a good day). Then export for the maximum payment you can get down from 100% to whatever it can export into that 3 hour window.

This seems sensible because you lower the battery cycles, it would be one complete cycle per day. Thoughts?

In my mind I'd be charging to 100 in the 2am to 5am window then exporting everything else during the day and forcing a discharge between 4 and 7pm. With my gen1 inverter I could maximally charge and discharge 7.8 in this period so something like £2 every day profit on top of whatever you export which cojld be 20 or 30kwh in the height of summer and that's if you have to fully charge your batteries.