DIY home solar grid tie

[gaz1]

Gaz1, not sure if this will be of any use to you but see below my figures since my system went in.
Garage is 3.87KWp (50 degree angle) and caravan port is 10.24kWp (8 degree angle), bit further north than you are looking for so anything comparative is likely to give higher outputs.
View attachment 398593

ive looked at your numbers

but your caravan numbers dont add up right via the very first total 2018 dec

200 then it gives 3850 that number dosnt add up even if it was right it dosnt match up up either with yearly too either nov/dec numbers either

 

[Fintray]

ive looked at your numbers

but your caravan numbers dont add up right via the very first total 2018 dec

200 then it gives 3850 that number dosnt add up even if it was right it dosnt match up up either with yearly too either nov/dec numbers either

The cumulative numbers are the total for both systems.

 

[J1nx]

Fintray, looking at the average for your garage roof you are getting 16% of peak generation in December but a fair bit less on the caravan, I’m guessing that’s simply the inclination of the panels?

Nice to see long term data, thank you

 

[Gareth J]

@gaz1 Just plug your proposed numbers into pvgis, it's pretty good and, barring a neighbour with an identical setup, the best you'll have to estimate the output. It does however, expect that you will generate the total potential of your panels - there's no option to undersize the inverter. Unless it's been altered recently.

 

[brewdexta]

@J1nx
@brewdexta

since weve just gone through a winter would you state what you have installed

how many solar panels in use
your power output from your solar panels
is your panels in the optimum position
would you both mind showing your winter power outputs for the winter both daily and monthly if possible

to be honest i would like to see both of your power outputs between southern and mid north solar collection ( mid north is hull to blackpool range to me )

I'm travelling at the moment so the data is limited to what the inverter uploads to the cloud. Ignore the revenue figures as I changed the price per unit from the SEG value to my current unit cost from ecotricity recently so the figure is probably meaningles.

First year figures with monthly break down. So far this year over 1MWh.

System is G98, so inverter limited to 3.68kW. I have 12 x 390W panels, given I'm up t'north I looked at the spec of the inverter and installed as many panels as I could without exceeding the max inverter specs. So the theoretical max of the panels exceeds 3.68kW. But that figure is to the grid/my house , it seems that the inverter will push a bit into the batteries as well as supply 3.68kW.

The panels are relatively optimised given the tight space the missus allocated me without going into stupidly over engineered complex tracking mode. In the colder months I get a bit of shading in the early/late day so will push the angle from 30 to 28 degrees to solve this.

 

[brewdexta]

Now monthly with daily breakdown

 

[minimutly]

The last line graph I posted shows current consumption/generation, as you can see we are now achieving almost 100% and as I have data from last June onwards we should easily now continue that through to September.
I now have the battery which has almost doubled the investment but it really allows us to harvest the otherwise wasted generation and being on a separate inverter allows peak loads to be covered better.

Winter generation is over 10% easily, December just gone was 45kWh, peak summer was 356kWh so coming on for 13%.

Careful with your percentages there you two - looks like you’re talking apples and pears. @Jinx looks like you’re using percent of usage? Normally solar output would be percent of potential output. Apples and pears.
Btw, @brewdexta , your numbers are very similar to mine, same size system etc. I’m not sure if the uk map would give me more theoretically, but 4000kWh has been achieved a couple of years, mostly 3800 to 3950...

 

[J1nx]

Careful with your percentages there you two - looks like you’re talking apples and pears. @Jinx looks like you’re using percent of usage? Normally solar output would be percent of potential output. Apples and pears.
Btw, @brewdexta , your numbers are very similar to mine, same size system etc. I’m not sure if the uk map would give me more theoretically, but 4000kWh has been achieved a couple of years, mostly 3800 to 3950...

My figure is percentage of max actual output vs min actual output on a monthly basis. So June vs December.

To me, the actual data is what matters but potential/theoretical is always interesting to compare with.

How would you calculate the potential, inverter potential or panel potential and then referenced to irradiance figures from somewhere? I don’t have a Pyro on this install but I do have local Pyro data, however cloud cover would still potentially be quite different even within a few miles.

 

[minimutly]

My figure is percentage of max actual output vs min actual output on a monthly basis. So June vs December.

To me, the actual data is what matters but potential/theoretical is always interesting to compare with.

How would you calculate the potential, inverter potential or panel potential and then referenced to irradiance figures from somewhere? I don’t have a Pyro on this install but I do have local Pyro data, however cloud cover would still potentially be quite different even within a few miles.

I dunno, but 100% is quite a claim for anything other than hours at a time - it’s possible that we could get a cloudless day, all day, but even then in warm weather the panel temps increase and reduce the output. And that’s without allowing for the tapering either end of the day - how do you model that?
So I guess you could use percent of peak maximum? But again this just gets you instantaneous power. For daily generation you might use your best peak day as 100%?
This is why quoting and comparing percentages is fraught. Personally I would use percent of my best month.

 

[Fintray]

Fintray, looking at the average for your garage roof you are getting 16% of peak generation in December but a fair bit less on the caravan, I’m guessing that’s simply the inclination of the panels?

Nice to see long term data, thank you

Yes that's correct, the 50 degree angle of the garage panels is much better in winter due to the low angle of the sun.

 

[J1nx]

I dunno, but 100% is quite a claim for anything other than hours at a time - it’s possible that we could get a cloudless day, all day, but even then in warm weather the panel temps increase and reduce the output. And that’s without allowing for the tapering either end of the day - how do you model that?
So I guess you could use percent of peak maximum? But again this just gets you instantaneous power. For daily generation you might use your best peak day as 100%?
This is why quoting and comparing percentages is fraught. Personally I would use percent of my best month.

Ah yes, I did specify but I probably wasn’t clear enough.

The 100% was a separate comparison, that was our personal consumption vs generation with storage. I also said almost 100% as high demand in the dark needs supplement from the grid and also the grid set point of the Victron inverter does float about a bit and take a second or so to respond to load changes.

Standing charge for electricity also excluded from above.

We are low users of electricity (Wood burners and ICE vehicles). We have a 2kW system (inverter limit). I think for my use I would ideally have 4-5kW of generation to cover a significant portion of the year whilst not going hugely overboard. If we went off-grid, I’d want 20kW generation at a complete guess, but that’s assuming I didn’t look at changing things for efficiency rather than the disproportionate outlay for a system of that size or alternative generation to PV.

 

[minimutly]

Ah yes, I did specify but I probably wasn’t clear enough.

The 100% was a separate comparison, that was our personal consumption vs generation with storage. I also said almost 100% as high demand in the dark needs supplement from the grid and also the grid set point of the Victron inverter does float about a bit and take a second or so to respond to load changes.

Standing charge for electricity also excluded from above.

We are low users of electricity (Wood burners and ICE vehicles). We have a 2kW system (inverter limit). I think for my use I would ideally have 4-5kW of generation to cover a significant portion of the year whilst not going hugely overboard. If we went off-grid, I’d want 20kW generation at a complete guess, but that’s assuming I didn’t look at changing things for efficiency rather than the disproportionate outlay for a system of that size or alternative generation to PV.

I think if you wanted to go off grid you would need something additional to solar, maybe a backup diesel for the dark months, wind if you can get it complements it well, but still not guaranteed.

 

[Gareth J]

I think if you wanted to go off grid you would need something additional to solar, maybe a backup diesel for the dark months, wind if you can get it complements it well, but still not guaranteed.

Plenty of winter days here with next to no wind or solar, even with a well sighted turbine.

 

[pressbrake1]

Ah yes, I did specify but I probably wasn’t clear enough.

The 100% was a separate comparison, that was our personal consumption vs generation with storage. I also said almost 100% as high demand in the dark needs supplement from the grid and also the grid set point of the Victron inverter does float about a bit and take a second or so to respond to load changes.

Standing charge for electricity also excluded from above.

We are low users of electricity (Wood burners and ICE vehicles). We have a 2kW system (inverter limit). I think for my use I would ideally have 4-5kW of generation to cover a significant portion of the year whilst not going hugely overboard. If we went off-grid, I’d want 20kW generation at a complete guess, but that’s assuming I didn’t look at changing things for efficiency rather than the disproportionate outlay for a system of that size or alternative generation to PV.

What I’ve found is even oversized (my workshop is 75kw) dull days just don’t do it.
My home system is off grid and in December it took several days to fill the batteries enough to do the hot water.
I think off grid 100% is possible but with a big battery bank that can ride out weeks of poor sun with care and suck up every last bit on good days

 

[Gareth J]

What I’ve found is even oversized (my workshop is 75kw) dull days just don’t do it.
My home system is off grid and in December it took several days to fill the batteries enough to do the hot water.
I think off grid 100% is possible but with a big battery bank that can ride out weeks of poor sun with care and suck up every last bit on good days

Probably an inter seasonal heat store would make all the difference. Banking heat when you don't know what to do with all the energy in summer and drawing down in winter, with only lighting and electronics and I suppose a heat pump to move the stored energy, left to power in winter.

 

[pressbrake1]

Probably an inter seasonal heat store would make all the difference. Banking heat when you don't know what to do with all the energy in summer and drawing down in winter, with only lighting and electronics and I suppose a heat pump to move the stored energy, left to power in winter.

I think they’re doing that in the Netherlands but with wind turbine energy

 

[minimutly]

Sorry both, but your thinking is flawed. A bigger battery still needs charging, and a bigger one more than a little one, so will take longer, or actually will spend longer discharged.
A massive heat store? Yes, but how long would that take to fill? And as it’s being filled how much energy is spare for use?
Ultimately it’s the law of diminishing returns vs cost.

 

[Gareth J]

Sorry both, but your thinking is flawed. A bigger battery still needs charging, and a bigger one more than a little one, so will take longer, or actually will spend longer discharged.
A massive heat store? Yes, but how long would that take to fill? And as it’s being filled how much energy is spare for use?
Ultimately it’s the law of diminishing returns vs cost.

Properly sized, an inter seasonal heat store won't be "full" after the first summer. It's a big civil engineering project at any kind of scale but not necessarily unviable, depending on the cost of just in time energy sources.

 

[gaz1]

Probably an inter seasonal heat store would make all the difference. Banking heat when you don't know what to do with all the energy in summer and drawing down in winter, with only lighting and electronics and I suppose a heat pump to move the stored energy, left to power in winter.

i was looking at the netherlands sand battery store 7m high 4m wide 100 ton of sand feeds a small city of heating

now this battery can be heated alot higher than water as it can reach 1000f temperatures

saves you looking for the info

Polar Night Energy Designs a Sand-Based Heat Storage System

Using multiphysics simulation, Polar Night Energy designed a cleantech heat storage system that relies on sand and the Sun. Read the full story here.

www.comsol.com

this will come in handy for those with swimming pools

video to sand storage

 

[pressbrake1]

Sorry both, but your thinking is flawed. A bigger battery still needs charging, and a bigger one more than a little one, so will take longer, or actually will spend longer discharged.
A massive heat store? Yes, but how long would that take to fill? And as it’s being filled how much energy is spare for use?
Ultimately it’s the law of diminishing returns vs cost.

I know that , I think it’s possible but not viable financially