I’m thinking of getting solar panels and a battery for our house.
What’s your setup like, and is there anything you wish you’d set up differently if you were going to install it again? What supplier are you with?
A company extremely local to us is offering 12x Aiko Energy panels (465 watt), with a Sunsynk 5 kW inverter and a 5.32kWh battery. Octopus Energy are offering a similar set up for a similar price, but they’re using 450 watt panels, so with using 12 panels I’d be potentially be losing 180 watts vs what the other company is offering. Is that a significant amount or would it basically not really amount to much additional power?
Check out diysolarforum.com
I’ve got a 11.64Kw setup it went live in July 2023 and I just hit 40Mwh generation. It does about 90% of my power needs. That’s including charging two EVs and a big AC.
I would have liked to go bigger but where I live going above 11.7Kw requires a bunch of extra paperwork and insurance.
Overall no regrets. I’ve generated about $6K in savings and it cost me $13K so I’m about halfway to break even. Power rates have gone up recently so my savings should also increase.
As far as battery recommendations there are a lot of factors.
If you have net metering and a good stable grid. It’s not worth getting a battery.
If you aren’t able to export and are going to generate much more during the day then you use battery makes sense.
If you can export but lack net meeting you have to look at the expected price difference between buying power at night and selling during the day. It may be more cost efficient to add more solar instead of a battery and use the extra generation to offset buying at night.
For battery if you want backup when the grid is down you need islanding. Otherwise everything shuts down for safety when the grid does.
The other thing to consider is a single line inverter vs micro inverters on each panel. If your panels are going to get the same amount of sun a single inverter is usually better.
If you have something like a tree that is going to start throwing shade on one panel much sooner than the others then micro inverters are better.
With a line inverter if one panel in the line has 50% shade and the others are in full sun the whole line is going to be at 50% generation. With micro inverters just the one is going to have low generation.
Micro inverters are less efficient however and as you have one on each panel you have many more points of failure.
Let me know if you have any other questions. I did my installation myself so I did a lot of research.
Here is a recent generation vs usage day for me.
I have had a 2.4kWp system for two years. Solis inverter, Pylontech batteries and a Myenergi Eddi.
The good: charging the batteries up at night (on an Octopus two rate tariff) means never paying more than 7p for electricity. In summer I maybe import 3kWh per day. Because the solar energy heats the hot water (via the Eddi) the gas bill has halved. The system I expect to last for >20 years and I expect full payback in around 7 years. A good investment. Since the inverter is chinese made they will probably remotely disable it before they invade, so I’ll get some advance warning and can brush up on my mandarin.
The bad: almost everything else I have installed (car charger, heat pump etc) has been more painful and required multiple visits from an electrician to sort out - I don’t want the solar batteries to discharge into the car when I charge it, and I don’t want the heat pump to drain the battery either. The installer was terrible and it took ages to get it all right. I had to hack the inverter with a modbus bypass to get it to work with Homeassistant. Thinking of getting aircon upstairs and dreading the conversation with the installer.
Overall: 10/10 recommend, wish the government would force everyone to have solar panels.
I’ve also got a solis inverter. Do you have any info or tips on your modbus bypass?
So far my only complaint is I hate the battery control settings. I haven’t found a way to set it only charge from solar and only discharg when the grid is down.
this github has some good tips and a kit list for an example modbus setup with an ESP32. I know you can also make more advanced ones with a Raspberry Pi and Home Assistant.
Discharging when the grid is down I’m now so sure about. The inverter has an “off grid” mode but you’ll need to check the regulations about having a live connection since it might be dangerous to have your property and cabling still be live when there is an outage - you might injure someone trying to repair the damage at the other end.
Thanks for the link.
I’ve got a islanded section for off grid and the balancer transformer. It’s just the settings for the battery don’t seem to allow for no battery export only local use.
I have frequent power outages so I want to export unused solar but save battery for the house. It feels likes there should be a setting allowing that.
I guess my solution that would be a UPS that detects the power outage, provides 1-2 minutes of power while a connected controller (a raspberry pi or similar) forces the inverter into off-grid mode. When power is restored, a connected current clamp/CT sensor can tell the raspberry pi to cancel off-grid mode.
A bit complex but I suppose the other option is relay isolators / mains contractors which are a bit too “high voltage” for me
Get a larger battery.
By far the lion share if the savings come from internal usage. Export payments are 20% of so of electricity costs, so you want to be using what you generated.
I have a 5.4kW array, and a 8.8kWh battery. 15% of the battery has to be reserved, so actual capacity is lower.
We basically live off grid for 6-7 months, but winter production is so low (aprox 20% of summer ) that it’s hard to even fill up the battery.
But a larger battery would help for those spring and autumn months when some days are good, some are bad.
For reference, comercial installation have a 4:1 ratio of battery capacity to production. In my case that would be 20kWh! Or 5 days of average consumption.
One final thing to say is that our battery system is capped to 3kW. So even when full, if we ask more electricity than that at any point we would be importing.
What this means is that going gas free is harder, as some appliances (hob, kettle) consume a lot.
Time of use tariffs have low import costs than the price Octopus will pay for export, so it’s actually better to export solar production than to self consume, so your first advice is inaccurate.
just had ours installed and even today when its cloudy and raining we are producing enough to run the house (low usage). couple of things to be aware of - On a normal system, if the grid goes down you cant use you solar or battery(may not be a problem for you), for this you need a back up box with off grid capability. There will likely be an export limit set by the DNO so the excess may get wasted anyway. 180 watts isnt much, possibly run a fridge on it
On a normal system, if the grid goes down you cant use you solar or battery(may not be a problem for you), for this you need a back up box with off grid capability.
Is this because there’s no way to dump any excess electric back into the grid? I don’t think this is too much of a worry for me though, I don’t recall a power outage in the past 8 years of us living here! touch wood
It’s a safety requirement. If the power company powers down a part of the grid for workers to safely perform work they don’t want your solar to kick in and kill the worker.
If you want your battery or solar to power parts of the house when the grid is down you need islanding. That disconnects part of the house grid from the street grid keeping any workers safe.
No - the inverter needs the 50hz signal from the grid AC to work.
If there is nowhere for the energy to go the inverter will lower the output from the panels. I think the main reason is because if they turn off the grid for maintenance, you cant start exporting and potentially kill the workers. There are also other complications like the inverter needing power before it can create power
you need a back up box with off grid capability
I thought this was usually included with a battery install.
If I were doing this all again I’d use Victron inverter kit with the self build batteries (Fogstar do a decent kit), for an entirely self hosted control system, and whatever panels fit the roof space best. But 180W is nothing to worry about. More important to find a second area for another array.
Oh, and you will want a hell of a lot more than 5kWh worth of battery storage. I have 14kWh and run low in winter when the panels make naff all (charge on cheap rate power to last all day)
Are batteries ok in the roof? I thought the temperature variation up there would be too much for them?
(Lazy question without searching for the answer myself)
Current guidance does not allow installation in a roof space, and limits capacity to 40kWh in most houses (80 kWh in detached or separate garage). Guidance, not law iirc.
But they are so heavy I would not place them on ceiling joists, I’d want them on a concrete floor
Solid advice right here.
I have 13.5 kWh battery storage that I charge overnight with cheap electricity if needed. During winter I could do with more storage.
I control charging of the battery (and EV) automatically based on expected solar production the following day, which I estimate using a forecast model I re-train couple of times per week based on latest data. The model uses Met Office weather model forecast for our area as input. Most days it’s accurate to within 1 kWh.
I have 16 LG panels spread so that they produce almost from sunrise to sunset + 5 kW inverter. This has worked really well. There is plenty of power to run air conditioning in the summer and even charge the EV, but winter months are meh. Sunny summer day: 25-30 kWh, winter 1-5 kWh.
I forgot to add that I’m with Octopus Energy. Their Octopus Go plan offers great rate overnight and is not too bad during the day at lest in our area. Their free energy sessions have also been in active use: battery charge, EV charge, immersion heater and sauna stove being on simultaneously does put the house electrical system to a test!
My aim is to use as much of the solar energy I produce myself, so I’m not bothered about exporting energy.
The quote I received from the local company (the 12x 465w) panels has come to £8,500ish, including installation. I might ask to see what it is with a 10kWh battery, and see if it makes sense. I did wonder if 5kWh would be enough throughout the winter, I’d imagine it might be only enough to get through the peak period.
Octopus’s provisional quote was £2k extra although I need to give them more specific information, so that quote might come down.
The way our roof is means we’d basically use all of it and it’s facing east/west which should give us a longer sunlight duration.
Check the quote which should state which battery is supplied, then one of the general suppliers, itstechnology, bimble solar etc.
A battery installation should be zero vat, so a single 4.8kWh US5000 Pylontech battery is like £720 ex vat These are 15 cell batteries and they are essentially plug and play. Some batteries are 16 cell batteries so have a little more power stored but seem to cost a lot more. Can’t mix and match batteries of different numbers of cells.
The batteries should essentially be supplied at cost, there is zero work to install more.
Decent price TBH. Should pay back in 5 to 8 years with the bigger battery and the right tariff (I think the best tariff is Intelligent Octopus Go and the fixed export tariff, ~15p/kWh export, but 7p/kWh cheap rate import, and need an EV)
The battery is a Sunsynk L-Series.
Luckily the whole package is VAT free, apparently that ends in 2027.
They’re partnered with EDF although you don’t have to use EDF. Unfortunately we don’t have an EV yet, and won’t for a while as I’d rather run our current car into the ground!
Yeah I ran my car until the engine light came on and swapped later on. It’s fine, no point trading in unless you can get a good deal IMO.
Personally, I’d ask for a quote with a different battery, that looks to be overpriced compared to others so extending the battery size will be more expensive than it should be.
Don’t get a solaredge inverter. In the new model they removed the lcd screen showing yoir production and to know how much you are producing or other statistics, you must use their online dashboard that stats costing after 10 years.
I’ve got a SolarEdge system but I’ve enabled the local ModBus to get the data so I don’t need to connect to the cloud for it.
Did you use specific docs for this? I have SolarEdge and wouldn’t mind going local with them too. I’ve got off most cloud services, but this one persists.
For Home Assistant? There are several about but this is the one that worked for me.
You need to enable it via the webconsole on the inverter. There is a magic reset sequence that will boot it up as an Access Point and then you connect via WiFi: full instructions
Cheers! Yes, I use Home Assistant for automations.
You are a savior, it’s a shame we must resolve to this, but at least there’s the option to do it. Still shame on them for removing the lcd screen
My US experience may not apply. https://lemmy.world/post/32326227
Absolutely no regrets. Solid investment. Pretty neutral financially, very safe diversification. Plenty of other benefits.
In a similar vein: any good hybrid inverters out there that play nicely with HomeAssistant (e.g. via Modbus or other)?
Is it worth getting 40 year guarantee? Arent most of these businesses going to be out of business when I need them?
Solis inverters work with HA via modbus.
nice, will check it out thanks!
I have 10x 340W panels and 2x 2kWh batteries. I’m very happy with them. I’ve had them just over 3 years now and I’ve saved about half the cost of the system. I got them through greenscape. The export rates are terrible, but I have an EV so I don’t export a lot (though I am often at work in the afternoon when the house battery is charged so I waste some there).
I sometimes think I should have got more battery capacity but it would take quite a long time to recoup the extra cost.
My octopus rate gives me 15p per kwH I export. The overnight rate is 7p per kwH so it makes sense to export as much as I can and charge the car on cheap rate.
The gap between sunset and cheap rate is about 4-8 kwH so rather than getting a battery my next step is a bi-directional charger so my car can cover the gap.
DIY is the way to go. You will be able to get a dramatically larger system for the same price. I do not recommend grid tie it’s not worth the rebate there’s a ton of red tape and you will have to install an insane amount of extra equipment if you want to be able to actually have power during a power outage. Using an off-grid inverter with self consumption means that it’s basically just a computer UPS on steroids and it also removes a ton of the installation red tape that exists for grid tie inverters.
They are actually quite simple to install correctly to code and then for extra piece of mind you can have it inspected by an electrician which is way way cheaper than having them do the installation. I decided to spend roughly $20,000 on solar and for that money I got an entire pallet of solar panels 50 of them 30 KW hours of battery and 12kWh of inverter output.
Getting the solar panels installed is a hell of a lot of manual labor that’s for sure definitely one of the better workouts I’ve had in a while but when I compared what any solar installer in my area would give me for that price? It was a fraction of the system less than half the total solar panel output half the inverter output no batteries and most companies don’t want to talk to you about a system unless it’s gridtied.
Cheers for your advice! Honestly it’s extremely unlikely I’d do it myself. I’d need to get at tonne of scaffolding and I wouldn’t know anything about attaching the panels to the roof or doing any of the wiring!
Just chiming in to say that Octopus support DIY builds from non-MCS accredited installers. You can literally self-certify your build and feed it back into their grid.
Good to know, cheers!
I can fully understand the roof part, that you can always get a roofing contractor for installing they will do it for a lot less and likely much better than a solar installer will. But the wiring is incredibly simple there’s literally just positive and negative on the solar panels. You just put them in series until you hit your desired voltage, then parallel strings after that. Solar panels use nice simple connectors that literally just click together, you plug those into some nice disconnect switches near the inverter and then from the switch to the inverter.
I love DIY maybe too much, but this strongly violates my “nothing structural, nothing roofing” rule.
They are both things I’d want a massive company to be doing, just from the sheer magnitude of the problems if they screw it all up.Exactly. There’s a high chance of me dropping a panel off the roof, or worse, myself.
Unless you are a part P registered electrician it is unlawful to connect an inverter to the consumer unit (and hence the grid) in the UK.
Also, the feed in tariffs in the UK are highly competitive.
Sure, it’s possible to get the panels bought and installed and wired up as a DIY project but that’s about it.
I did explicitly specify a non grid tie unit. An off-grid unit that does not do any grid feedback is literally no different than plugging a UPS in to back up your computer in terms of the impact on the grid . It will accept the grid as an input to pass through but it will never feed power back into the grid thus a lot of the red tape goes away.
Maybe it’s different in the UK but for the US a self consumption off grid inverter you do not need to even inform the power company much less be any type of electrician it’s only if you are doing a grid tie inverter that will put power back into the grid that suddenly there’s a lot of requirements.
In the UK any new electrical circuit, which includes an EV charger, solar DC/AC inverter, cooker or lighting circuit etc is notifiable work and must be completed by a part P registered professional.
It doesn’t matter if it’s a self install of an inverter that can be zero rated for export, if the house consumer unit is connected to the national grid you can’t self install (unless you are a registered professional as stated). Essentially to connect solar panels to a house that is also connected to the grid will always have to use a grid tied inverter.
Only way to use an off grid inverter, which is what you described, is if the house is entirely off grid (and therefore has it’s own earth which is another point but not really worth going into). The description of an off grid inverter you use would not be the definition used in the UK in relation to building regs (it would be a grid tied system because it is connected to the grid, pass through is irrelevant).
Oh, well that’s stupid and overreaching regulation. I can only imagine what the services cost when it’s forced like that probably worse than around here. Imagine not being able to install a new light circuit because you aren’t a certified electrician that’s nuts lol.
