Depth for buried DC cables

[Roger440]

3 hours ago, FarmerN said:

Just check spoil from trench for bits of land drain, clay or plastic. Up to you if you repair any old drains you cut, but at least you know they are there if a wet spot develops in future.

We have GSHP , one of the down sides is a dry field is now wet !

 

The good news is, i know where the land drains are! I plotted my route accordingly.

[Roger440]

1 hour ago, JohnMo said:

Just do AC coupled they use a normal inverter

 

Why I am currently getting 12p looking at Octopus Prime which will pay 16p in peak periods. So would question that figure.  If you don't have a smart meter and that's the reason, get one

 

Size battery to suit that consumption, not 5kW

 

Our house started with 3kW of PV, and had a gas boiler, we paid around £180 a month all in, we now pay £52, with vertical PV (winter good summer poor) and 13.5kWh battery.  So around £1500 saving a year and I already had PV.

 

Wet soil retains heat better than a dry one, our soil is 100mm thick then sand, we would need almost double the pipes compared to wet soil

 

 

 

Still no clue how to do multi quote, so bear with me.

 

Not really got into detail on possible inverter set up yet. My priority was a cabling decision quickly to make use of the dry weather for trenching.

 

Im limited to 3.86 because that all you can do without an application. (are we talking cross purposes here?) Given they are already having over voltage issues in summer, and im on a spur feeding 6 properties, some very lightly used (MOD) i cant see approval being forthcoming.

 

Im sure you have posted your financials before, but ive no idea why its so different from memory. Current bill is £280 a month, 9000kWh a year. Heavy in winter, light in the summer due to workshop.

 

A bigger battery, ie 10Kw increases payback as ill never fill it during the winter with a 4.5kw array It will only be useful in summer.

 

Doubling the size of solar and batteries does reduce the payback, but to roughly the same as the current array with 5Kw  battery. (the only saving will be the cabling as its already there.

 

If im missing something obvious im all ears, but i cant see it at the moment. Ive not taken into account a heat pump as thats not a certainty, or in the immediate future.

Edited 16 hours ago by Roger440

[-rick-]

6 minutes ago, Roger440 said:

Im limited to 3.86 because that all you can do without an application. Given they are already having over voltage issues in summer, and im on a spur feeding 6 properties, some very lightly used (MOD) i cant see approval being forthcoming.

Unlikely maybe but it's easy to do so no harm in trying. (though sensible not to base decisions on access to more)

 

6 minutes ago, Roger440 said:

A bigger battery, ie 10Kw increases payback as ill never fill it during the winter with a 4.5kw array It will only be useful in summer.

 

In winter you fill the battery overnight with cheap rate electricity and run your workshop off it during the day.

 

In summer, you export the max you are allowed and charge the battery with the rest. Then, when the sun goes down, you keep exporting until the battery has enough room to take the next days solar input.

 

These two steps combined minimise your bill in winter and maximise you export (earnings) in summer.

 

6 minutes ago, Roger440 said:

If im missing something obvious im all ears, but i cant see it at the moment. Ive not taken into account a heat pump as thats not a certainty, or in the immediate future.

 

See above. Do the calcs based on what you are doing right now. Given you have the panels and inverter for free you should be able to make it work fairly comfortably.

 

What size solar array and inverter do you have?

 

Is the inverter approved for export G.98 and G.99/G.100? (It would be a big hitch if not, likely requiring a new inverter)

[Roger440]

3 minutes ago, -rick- said:

Unlikely maybe but it's easy to do so no harm in trying. (though sensible not to base decisions on access to more)

 

 

In winter you fill the battery overnight with cheap rate electricity and run your workshop off it during the day.

 

In summer, you export the max you are allowed and charge the battery with the rest. Then, when the sun goes down, you keep exporting until the battery has enough room to take the next days solar input.

 

These two steps combined minimise your bill in winter and maximise you export (earnings) in summer.

 

 

See above. Do the calcs based on what you are doing right now. Given you have the panels and inverter for free you should be able to make it work fairly comfortably.

 

What size solar array and inverter do you have?

 

Is the inverter approved for export G.98 and G.99/G.100? (It would be a big hitch if not, likely requiring a new inverter)

 

Hmmm, i did do the calcs 🤔. Though i did use AI to assist me. Which could be a problem!

 

The array is 4.5kw. The inverter not sure. Its quite old, though still brand new. Ive worked on the basis of a new one. If i use the old one, its a bonus.

[-rick-]

4 minutes ago, Roger440 said:

Hmmm, i did do the calcs 🤔. Though i did use AI to assist me. Which could be a problem!

 

You saying you'd never fill that battery suggested that what you did may not have accounted for using the overnight cheap rate to charge. Should always be possible to fully charge overnight.

 

Always worth checking the AI.

 

4 minutes ago, Roger440 said:

The array is 4.5kw. The inverter not sure. Its quite old, though still brand new. Ive worked on the basis of a new one. If i use the old one, its a bonus.

 

Ok sorry, I thought it was a bigger array than that. In that case, prob not worth worrying about going over the G.98 limit. Just set those panels up to generate the maximum you can during winter/shoulder seasons.

 

As far as mounting the panels go, do you have planning/visual considerations? You can get really cheap if you don't have to worry about that. (Scaffold poles set in concrete holes, unistrut, etc)

[Roger440]

10 minutes ago, -rick- said:

 

You saying you'd never fill that battery suggested that what you did may not have accounted for using the overnight cheap rate to charge. Should always be possible to fully charge overnight.

 

Always worth checking the AI.

 

 

Ok sorry, I thought it was a bigger array than that. In that case, prob not worth worrying about going over the G.98 limit. Just set those panels up to generate the maximum you can during winter/shoulder seasons.

 

As far as mounting the panels go, do you have planning/visual considerations? You can get really cheap if you don't have to worry about that. (Scaffold poles set in concrete holes, unistrut, etc)

 

Sounds like i should re-run the numbers.

 

No contraints (at least none i will concern myself with) around the panels. Though id really like to avoid concrete as it would be a bit of a nightmare to get it down there in any useful quantity. Will consider any solution. but 80mph winds are the real problem.

[JohnMo]

9 hours ago, Roger440 said:

limited to 3.86

So 3.86kW, so not pence. 

 

3.86kW exported over 6 hrs is 22kWh.

9 hours ago, Roger440 said:

10Kw increases payback as ill never fill it during the winter

A 10kWh battery in winter would be filled from the grid. You basically get a time of use tariff so you get cheap periods. My current tariff allows me to fill at 10p per kWh instead of 27p or whatever the standard tariff is.

 

8 hours ago, Roger440 said:

concrete as it would be a bit of a nightmare to get it down there in any useful quantity

My array is 4" posts and uni-strut and I used postcrete, easy to move from A to B

[Roger440]

4 hours ago, JohnMo said:

So 3.86kW, so not pence. 

 

3.86kW exported over 6 hrs is 22kWh.

A 10kWh battery in winter would be filled from the grid. You basically get a time of use tariff so you get cheap periods. My current tariff allows me to fill at 10p per kWh instead of 27p or whatever the standard tariff is.

 

My array is 4" posts and uni-strut and I used postcrete, easy to move from A to B

 

Yes, i recall your pictures. But isnt there a bank/tress behind offering some level of sheilding?

 

[JohnMo]

11 minutes ago, Roger440 said:

 

Yes, i recall your pictures. But isnt there a bank/tress behind offering some level of sheilding?

 

Tree behind, but panels at top of bank - prevailing wind is straight at the panels

[JohnMo]

@Roger440

Just did my maths for this year to date

 

Imported £450 (4500kWh at 10p) of energy, while exporting exported £200 (1700 at 12p), so cost so far is £250. Plus since May earned £92 from Axle, so really cost is £158. Have used 7000kWh which at capped rates would have cost £1800, so far this year I am up £1650 already.