@upnorthandpersonal, that’s a serious piece of engineering. Designing and building a 14kW ground-mount array with 120 kWh of storage (heading toward 200 kWh) is not a hobbyist setup. 🤣 

A few obvious questions come to mind. How far are you from the nearest town or grid connection point? In other words, was this primarily an economic decision, a resilience decision or simply geography making the choice for you? At that latitude, winter solar yield is marginal to negligible I would imagine, so your storage capacity is clearly about buffering seasonal shoulder periods rather than bridging the full winter. I’m curious what your annual consumption profile looks like in kWh, and how much of that is thermal versus electrical.

On the generator side, how much bio-diesel are you actually producing per year, and what does winter charging translate to in litres per month? Charging ‘once or twice a month’ suggests your baseline winter electrical demand is relatively disciplined. Are you running the generator purely to charge batteries at high load for efficiency, or also covering direct loads simultaneously? It would be interesting to know the generator size and your typical charge rate into the battery bank.

And how are you handling water supply and wastewater off-grid… drilled well, filtration, grey-water treatment?

Posted by: @editor

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How far are you from the nearest town or grid connection point? In other words, was this primarily an economic decision, a resilience decision or simply geography making the choice for you?

Actually not that far, however, the cost of my initial system (10kW solar and 28kWh battery, with inverters, charge controllers, etc.) was slightly under the cost of getting power to my plot (10k Euro). Now, of course a sane person would have connected to the grid in any case, however...

Posted by: @editor

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was this primarily an economic decision, a resilience decision or simply geography making the choice for you?

I wanted to be independent of utilities. No monthly bills. The only cost I really have are the property taxes. I have my own water (from a well yes), waste water processing plant, etc. The independence is what I wanted, and while there is of course the up-front cost that comes with that, it's worth it for me. Heating costs me nothing (I get firewood from my own forest) except for some effort. By designing the place to be efficient from the get go, the amount of firewood needed on a yearly basis can be prepared in a few weekends per year, and of course the heat pump brings it down as well.

The waste water processing plant is a two stage anaerobic - aerobic system. This eliminates the need for a large leech field; the water coming out of the system is directly, and legally, discharged into nature (we have strict standards for that here).

Posted by: @editor

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At that latitude, winter solar yield is marginal to negligible I would imagine, so your storage capacity is clearly about buffering seasonal shoulder periods rather than bridging the full winter.

Yes, and to lower the times I need to run the generator to charge the battery. Once or twice a month in winter only. I need about 5kWh per day in winter without making sacrifices for comfort (this includes washer, dryer (heatpump based), dishwasher, etc.). The design take this into account: my dishwasher uses the hot water connection, so it doesn't need to rely on electric to heat the water for example.

Posted by: @editor

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On the generator side, how much bio-diesel are you actually producing per year, and what does winter charging translate to in litres per month? Charging ‘once or twice a month’ suggests your baseline winter electrical demand is relatively disciplined. Are you running the generator purely to charge batteries at high load for efficiency, or also covering direct loads simultaneously? It would be interesting to know the generator size and your typical charge rate into the battery bank.

With the load as mentioned above (5 kWh/day) I need 150kWh per month, for three months where I assume no generation (November, December and January). That means I need to generate 450kWh over winter. My generator gets 3kWh per liter, which means about 150 liter. I tend to make a batch of 200 liter, with whatever is left after winter used to run the tractor (to get wood from the forest, clean snow, etc.). My cost to make the diesel sits around 20 cents per liter, so 30 Euro. 

And yes, the generator is only used to charge the batteries, running at its optimal working point and producing about 10kW output going into the battery. 

Now, I don't have to do this. It's just that it's part of the fun. The feeling of being independent, that the house can be at +25C when it's -40C outside without it costing me anything really, that the wife and kids can take as long and as hot a shower as they want, that I have so much power in summer that I can do things like run a food dehydrator 24/7 to store apples, mushrooms, etc. for winter. That I can process all the firewood needed with electrical tools, run the sauna as much as I want. It's worth the upfront investment for me.

Like I mentioned, I have the entire set-up, with calculations etc. written down here. 

@upnorthandpersonal thank you for sharing details of your home - I thoroughly enjoyed reading your blog posts about your off grid home. Very impressive!

Posted by: @editor

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Kalosórisma @mk4. Thanks for sharing.

One of my objectives this year is to see how heating requirements vary across Europe, is I'm glad you've posted here. 

I am seeing people from other countries also (Finland, France) joining the forum and I am very glad!

One thing I have noticed wandering around the various threads is that there seems to be very little adoption of solar water heating in the UK (of course I may be wrong and please correct me).

Granted, UK is not the sunniest place in the world but I have noticed more than decent yields of PV energy vs installed power, meaning it cannot be that bad. And yes, most such solar systems actually require sun rays (not just light available even in overcast conditions), but still I believe you could greatly benefit from them.

They are relatively low cost (over here with 2k euros you get a decent 160lt installation) and they have practically 0 running cost. After installing the heat pump, I discovered than even during February with OATs ranging from 5 to 14 degrees, just 2 hours of (even intermittent) sunshine can heat 160lt at >45 degrees.

I looked at google-provided statistics: average annual sunshine hours in the UK is half of that of Greece (3000 hours), but south England average is 1900 hours. So you may well have a use for solar panels. Over here, we have an installed base of circa 5.7m sqm and rising. 

Food for thought 🙃 

Posted by: @mk4

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One thing I have noticed wandering around the various threads is that there seems to be very little adoption of solar water heating in the UK (of course I may be wrong and please correct me).

I agree they are very rare. The systems made more sense before PV became cheap. In Greece that industry developed early on but at that time here, people were not allowed to have external tanks etc. So it gained critical mass there, the install base grew with manufacturers and a network of installers. 

In the UK, you would not find many experienced installers for that. And now that solar PV is much cheaper to install, I would be surprised if thermal could compete with PV (as it competes for roof space and it is probably much more sensitive to orientation). A quick search tells me systems would cost £4k+, very close to a 4kw (max) PV system. 

Those water heating systems do not have the same reliability as PV. With the risk of sounding harsh, are people not replacing those unused systems with Solar PV in Greece yet? 

I also believe that the initial PV technology would not work as well under strong heat from sun. That has never been a problem here 😉. 

Posted by: @batpred

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I agree they are very rare. The systems made more sense before PV became cheap. In Greece that industry developed early on but at that time here, people were not allowed to have external tanks etc. So it gained critical mass there, the install base grew with manufacturers and a network of installers. 

Indeed, they started getting traction in the '80s and a big local industry developed around them. Nowadays we are actually heavily exporting in the area around the Mediterranean.

Posted by: @batpred

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In the UK, you would not find many experienced installers for that. And now that solar PV is much cheaper to install, I would be surprised if thermal could compete with PV (as it competes for roof space and it is probably much more sensitive to orientation). A quick search tells me systems would cost £4k+, very close to a 4kw (max) PV system. 

Over here, solar thermal are way cheaper than PV. And they require no license from the DNO (this alone costs some 400 euros). They need to be south facing to get advantage of winter solar radiation. But they are easily installed in flat rooftops that come in abundance in Greece. Not the prettiest of sights, but very energy efficient. And I guess the fact that we do get sunshine also during winter (albeit not every day) helps in making them so popular. 

Posted by: @batpred

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Those water heating systems do not have the same reliability as PV. With the risk of sounding harsh, are people not replacing those unused systems with Solar PV in Greece yet? 

In fact, the average life span is 20 years and ROI is less than half of that. I dare say nobody replaces solar thermal with PV. The ones who can afford it, add PV panels. Government grants help in household PV adoption, but the installed household base is as of yet an insignificant fraction of the solar thermal one. The fact that in the cities most people live in blocks of flats does not help either. There is however a large installed base of commercial PV parks than contributes significantly to the country's RE consumption.

Posted by: @batpred

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I also believe that the initial PV technology would not work as well under strong heat from sun. That has never been a problem here . 

This is one of my worries regarding our 2024-installed rooftop PV panels and the battery located in the garage that easily surpasses 30 degrees during summer. But I guess I have to accept it and move on! 

.

Posted by: @mk4

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Posted by: @batpred

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Those water heating systems do not have the same reliability as PV. With the risk of sounding harsh, are people not replacing those unused systems with Solar PV in Greece yet? 

In fact, the average life span is 20 years and ROI is less than half of that. I dare say nobody replaces solar thermal with PV. The ones who can afford it, add PV panels. Government grants help in household PV adoption, but the installed household base is as of yet an insignificant fraction of the solar thermal one. The fact that in the cities most people live in blocks of flats does not help either. There is however a large installed base of commercial PV parks than contributes significantly to the country's RE consumption.

Thanks, here we have a body MCS that accounts for some significant uplift in PV installation costs. But the connection to the DNO is included when an MCS certificate is produced. I wonder if ikea will be selling the balcony diy pv kits there..

To be honest, I would rather pay €400 to a DNO assuming the rest are standard electricians costs. That seems very good value and your very decent yield must help. 

Posted by: @batpred

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I wonder if ikea will be selling the balcony diy pv kits there..

I don’t know about IKEA but for sure some DIY chains (like Leroy Merlin) do. A plug and play set of panels that you plug in one socket.

One of the reasons we started the PV+battery journey was staying a week without electricity in 2021 after a heavy snowfall (lots of fallen trees damaged the distribution network).
I’ve been flirting for sometime with the idea of getting as 2nd rudimentary backup such a kit (to be installed on the spot if our rooftop panels are covered with snow, just to power communications) but I was put off by its size…. We ended up with a backup petrol generator that has never been used up to now. 

I would be very much interested though to hear and learn from people who have used DIY PV kits as I have not abandoned entirely the idea. And I have extended family who are also interested.

Posted by: @mk4

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I don’t know about IKEA but for sure some DIY chains (like Leroy Merlin) do. A plug and play set of panels that you plug in one socket.

..

I would be very much interested though to hear and learn from people who have used DIY PV kits as I have not abandoned entirely the idea. And I have extended family who are also interested.

I meant plug-in like just to connect to a socket. 

We do not have Leroy here, but B&Q seems to have tried a similar approach. 

I see that in France, there are plenty of items Leroy sell as DIY.  

A couple of threads highlighting risks and that you may find useful to post on 

• the challenges of the plug-in DIY route these days in the UK
• this one is more about going DIY with classical solar PV

Did you consider changing the angle of some of the panels so that no snow can sit on them?

Location: near Lyon, France

12kWp on the roof, 2x Solis S5 6kW hybrids, 20kWh Pylontech

So far pretty good

@bobflux 

Prey what are the SOC% limits you have set for your battery?

Posted by: @batpred

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I meant plug-in like just to connect to a socket. 

We do not have Leroy here, but B&Q seems to have tried a similar approach. 

I see that in France, there are plenty of items Leroy sell as DIY.  

Here is an example of local Leroy offerings (in exotic greek...)

Posted by: @batpred

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A couple of threads highlighting risks and that you may find useful to post on 

Thank you! I did look through them and I got dizzy by the technical level and heated discussion!

Posted by: @batpred

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Did you consider changing the angle of some of the panels so that no snow can sit on them?

Our PV panels are bolted on the rooftop, they are the first to accumulate snow. What I had in mind is to store the plug and play kit in the garage and only install it in a south facing balcony in case of emergency (having also our house cut off the grid, to be reconnected only after grid restoration would have been completed for grid personnel safety reasons)