Off grid and solar

NeverEnoughCake

Hello, new to this site and hoping for some good info.
We are in the process of sorting out a rural self build, we looked into connecting to the DNO but it will cost approx £7,000 (and we have to hire a digger and dig our own trench!) So looking at plan b.
On doing some research we can get a decent 3-4 k solar system with battery, we will have an LPG cooker and hot water heater, and heat in the winter from a log burner. We will ground mount the panels so that they can be adjusted to follow the sun and be south facing. We are a couple so no huge electricity usage. There are many websites with all sorts of facts and figures, but my question for anyone who is totally of grid is will we be able to run fridge and freezer 24/7 off the battery.
Cheers.

ajbell

A couple of caravan leisure batteries would probably do the trick.

Coastalwatch

Hi NEC and Welcome.
I'm no expert but do have both Solar panels and a fridge/freezer plus 10 cu ft chest freezer. Sadly no battery as yet. What I can state is that our overnight electricity consumption is approx 110 Watts/hour. Other than two clock radios and a router I believe the majority of it to be down to fridge and freezer. So about 2.5kWh's per day to run them. You don't say what size battery you are considering but suspect that even in the darkest days of poor output you stand a good chance of running them uninterrupted if you can prioritise their usage.
Others more well informed members may chip in also with helpful info but I don't think it's out of the question providing you're not running anything with a heavier consumption.

NeverEnoughCake

Thank you
The kit we are looking at Is 10 x monoLG360Q1C panels with lithiumBYD-B-PLUSL 2.56KW battery. We are a couple, with family members staying regularly which increases household to 6 for a few days at a time. The battery will be needed for fridge, freezer, TV and DVD, lighting (all LED) and most importantly kettle (but we could get an old whistle one for the gas cooker)outside of daylight hours. Daytime usage would be washing machine, occasional TV, vacuum cleaner, heated airer during winter months, lighting fridge and freezer. In your opinion would the kit be sufficient, inefficient or overkill?
Cheers

mre15

I personally think you might struggle with just 1 battery, you could also save money by going for some cheaper panels and put that towards another battery.
The LG panels are good but also very expensive compared to other brands, unless your limited by space more panels from a different supplier could give more output for less money.

Coastalwatch

NeverEnoughCake wrote: »

Thank you
The kit we are looking at Is 10 x monoLG360Q1C panels with lithiumBYD-B-PLUSL 2.56KW battery. We are a couple, with family members staying regularly which increases household to 6 for a few days at a time. The battery will be needed for fridge, freezer, TV and DVD, lighting (all LED) and most importantly kettle (but we could get an old whistle one for the gas cooker)outside of daylight hours. Daytime usage would be washing machine, occasional TV, vacuum cleaner, heated airer during winter months, lighting fridge and freezer. In your opinion would the kit be sufficient, inefficient or overkill?
Cheers

Firstly I'm not offline so have no practical experience to fall back on. As mre15 stated, along with all you are hoping to run from it then a 2.65 kWh battery is unlikely to be sufficient in the winter months. In fact I suspect the system itself would not produce enough energy for you needs during this period either. So its by no means overkill.

By putting your location and system size into the website linked below you will be able to get an estimated monthly output in kWh's for each month of the year. The figures given being based on historical analysis of the weather locally to you.
Apart from a tumble dryer then electrically we ran similar items to yourself and consumed approx 7kWh's per day throughout the year. We have an 8.85kWp system installed which generated 264 kWh last December, while that averages out at 7.68 kWh's daily there was a run of six consecutive days when generation was below this with 1.34 kWh being the lowest and 4.85 kWh being the highest.
Sorry, not trying to put you off and for 8 months or so of the year you may be perfectly ok, it's just how you manage during the winter months which would limit your usage. Have a look at the site and see what figures you come up with.



(PVGIS) - European Commission v5

NeverEnoughCake

Thanks coastal watch
Looked at the link, too complicated! Will look into extra battery to see if that will help. Looks like it will be candlelight around the wood burner of a winter's night..could think of worse things. We have little choice unless we want to pay thousands for a grid connection, and then pay for the electricity every month. Thank you all for your input.

Coastalwatch

Just plugged your 3.6 kWp system into PVGIS. Not knowing your location I based it in the middle of the country, Birmingham, so you will vary somewhat depending how much further north or south you might be.
I also based it upon the panels facing due south and at the optimum slope of 35 degrees. As you will see the lowest month being Dec at only 116 kWh's so about 3.7 per day. Any shading that occurs upon the panels will affect output adversely.

As mre15 suggested, if possible it would be well worth trying to fit more panels. Space and funds allowing of course.





Monthly PV energy and solar irradiation
Month Em Hm SDm
January 129 42.1 16.7
February 184 59.8 41.7
March 335 110 35.3
April 417 140 56
May 437 150 37.5
June 440 153 46.1
July 450 158 36.2
August 390 136 39.8
September 335 115 28.7
October 231 77.1 28.8
November 140 46.4 19.8
December 116 37.6 16.2
Em: Average monthly electricity production from the given system [kWh].
Hm: Average monthly sum of global irradiation per square meter received by the modules
of the given system [kWh/m²].
SDm: Standard deviation of the monthly electricity production due to year-to-year variation [kWh].
PVGIS

Zarch

My worst day in December was on the 5th, only generating 0.25kWh all day
Panels woke up at 10am (13w), peaking at 143w around 11am then went dark at 2:50pm after generating less than 60w all day.

Some days during the winter this happens, even with a 5.1kWh system.
The day before was 4.5kWh so definitely peaks and troughs. My PVGIS average for Dec is 3.7kWh. I had a max day of 6.7kWh.

My baseline usage (router, nas, sky box, fridge etc) fluctuates between 150w-200w. So on those bad winter days my solar is not even covering baseload.

Hopefully this gives you some idea of those bad days?

gefnew

Hi
If you are rural would a wind turbine help balance things out.

Martyn1981

NeverEnoughCake wrote: »

Thank you
The kit we are looking at Is 10 x monoLG360Q1C panels with lithiumBYD-B-PLUSL 2.56KW battery. We are a couple, with family members staying regularly which increases household to 6 for a few days at a time. The battery will be needed for fridge, freezer, TV and DVD, lighting (all LED) and most importantly kettle (but we could get an old whistle one for the gas cooker)outside of daylight hours. Daytime usage would be washing machine, occasional TV, vacuum cleaner, heated airer during winter months, lighting fridge and freezer. In your opinion would the kit be sufficient, inefficient or overkill?
Cheers

Hiya, I'm also on-grid, but have enjoyed reading much this last decade from off-gridders on the Navitron forum/site.

TBH, they have much bigger batts, usually lead acid, and perhaps 40kWh+. There seems to be a growing interest in lithium, it's just the cost.

As asked on this thread, is a small wind turbine possible? They are apparently hard work, and need to be loved, but will help in the winter when PV is poor.

Presumably you'll ground mount with a winter bias, so steep pitched, unless you hope to alter the pitch, which I think is what you meant.

Again, work on worst case, which might be 3+ days of next to no generation. If you have the space go bigger, much bigger, and (as also mentioned) you might find that more panels of say 280-300Wp might be cheaper than 360's, which are probably quite expensive (per Wp).

Also worth researching off-grid fridges and freezers, as I suspect there could be an issue with the massive draw that a freezer can pull, just for a second, when the compressor kicks in, I'm sure I saw something like 2 or 3kW as a peak - short, but you'll need kit that can cope with it.

Gut feeling is that this may be hard, but £7k just for the connection, would buy you most of the kit (PV, inverter, frames, cables etc etc) and a back up gennie (cheap petrol model), but perhaps not the batts. But that would put you ahead, as the DNO connection only allows you the opportunity to buy leccy, not make your own with free fuel (sunlight).