Solar Power Thread

[itareanlnotani]

Hi Rich (homebug),

In short - the inverters can be programmed to not discharge past a certain rate. The solar industry already has plenty of equipment that caters for these scenario's. Remember Solar has been in use since the 70's, so its quite a mature industry.


I went with the Vectron Multiplus units as those seem to do what I need.
They can "talk" to my Grid Tied Inverter and lower frequency to tell it to reduce power output, or completely shutoff if needed.
They'll also lie to the GTI and tell it the mains power is ok, so that we have a house micro-grid. It also shuts off the supply to Eskom as per G59 regulations.

My system will work as follows (as soon as I finish installing it this weekend):

Setup:
10KW 3 phase inverter (Growatt) with 4KW odd of panels on roof.
3 x Vectron 3KW / 24v Multiplus
2 x 12v / 220Ah batteries (minimal battery, keeps us alive when Eskom is dead).

Scenario's
Daytime, Eskom is working -
Solar feeds DC into the GTI (grid tied inverter).
GTI feeds A/C out into battery inverters (BI) which top up battery over DC, the AC output of the inverters goes to house use.
If GTI feeds too much A/C into the BI, then it diverts to the house.
Eskom power isn't used, but it is available if demand exceeds GTI load.

Daytime. Eskom is not working -
Solar feeds DC into the GTI.
BI keeps the GTI online by running off battery, and keeping A/C alive. Eskom side input is shut off by BI as per G59 regulations.
GTI continues to provide power to BI, and it diverts some to battery, and rest to house circuit.
If GTI provides too much power to BI, then BI frequency shifts the AC down to tell the GTI to reduce the power output.


Nighttime. Eskom is working -
GTI is offline.
BI will trickle charge batteries if necessary to keep float voltages up
*I can also buy enough batteries to run completely offgrid (about 8 more 12v/220Ah batteries for our typical winter house usage) if i wanted, and not worry about Eskom. I'm leaning toward that if they increase fee's more.


Nighttime. Eskom is not working -
GTI is offline.
BI will provide power from batteries to keep house alive.
BI will supply house up until a 60% discharge, then shutdown (programmable) - should last us about 4-5hrs, which is longer than the typical 2hr power outages we've been having.


I have a 3 phase grid tied system, so my usage is not typical. I knew I could afford a grid tied initially, then move to a battery tied later, so I went that route. Its more expensive, but it allowed me to fund things.

My current setup is more or less described here - http://www.victronenergy.com/live/ac_coupling:start

...and my new bits to install here -





and roughly a year of KW here




My future build (for my new house in Capri) will be completely offgrid - Panels -> DC inverter -> batteries / AC inverter -> house grid. (single phase). Looks like I'll spend about 40k on batteries, 60k on 9kw of panels, and 30k on inverter + chargers for that (rough guesstimates).

 

[MagicDude4Eva]

Question: What is then your typical running cost (i.e. TCO / ROI) when being off-grid or partially off-grid - i.e. maintenance of batteries/solar panels etc?

 

[AchmatK]

Snip....

Do you have a contact that can do a complete installation.



I have about R90k to spend in order to go grid tied. The system should be simple enough for me to add batteries as funds become available. Batteries is not a major consideration for now. I just need enough for my exports to offset my imports for now.



We have hectic wind in Somerset west so might also consider a small 1kw/2kw vertical axis wind turbine in addition to the solar panels to assist with night time power generation.

 

[itareanlnotani]

If you're in Somerset West, I'd recommend going down to the nice people at Ex-Solar, and having a chat.
I bought my batteries, and inverters from them yesterday.

They're not the cheapest, but they are helpful, and know what they're doing.

If you want to read about what I did - my blog about it is up at http://goingsolar.co.za
I did my own install though, and brought in panels, mounting and inverter from China (where I work most of the year).
Its not too hard to do though.

If you really want solar, my suggestion (as always) is to minimize your current usage.

Key items -
1) Replace your hot water geyser with a solar one, or two or three.. (I have 2 x 150L for 300L of hot water for a 2 people house, works well, I'd scale up for a larger house / user base).
2) Go gas for cooking, and heating kettles.
3) Replace all the lighting with LED.

Heating water is usually a large culprit in billing. You may also want to consider that dishwashers and washing machines can often be hooked up to the hot water supply to save money on heating water.
Things that run regularly throughout the day - pool pumps are often good to stick on smaller daytime solar panel circuits if you don't got the whole hog.

*Then* look at your usage, and see if going solar is worth it.

You can also PM me and ask questions, I'm usually happy to answer stuff.

 

[itareanlnotani]

Question: What is then your typical running cost (i.e. TCO / ROI) when being off-grid or partially off-grid - i.e. maintenance of batteries/solar panels etc?

Solar Panels don't really incur any maintenance. Rain clears off the dust/dirt that accumulates, and thats really the only maintenance thats needed. Mine have been up a year now, and the only thing I've really done is go up to the roof to check the mounting every now and then after one of the Cape's finer winter storms to make sure things are still mounted securely. So far we've lost half a tree this year, but no panels.

Batteries - depends how much you discharge them. Lead Acid based - eg AGM / GEL / Crystal etc don't really like being discharged fully - it tends to reduce the lifespan somewhat. Ideally you don't want to go below about 60% discharge before topping back up if you want to get 10-12 years out of a battery. You also want to keep them in a cool ventilated place - heat kills.

Key points -
Full discharge / charge cycles and temperature kills batteries. Avoid doing that!

I don't have any real data on usage yet for batteries as I literally just bought mine, and haven't even unpacked the boxes yet.
I'll be programming the inverter to 60% discharge though, and they'll be kept in a cool location. I expect to get about 7-10 years out of them (they're rated for 10 years allegedly).

Right now I think I'll be in the R120-130k range for my current complete setup (including the batteries and inverters I just bought).
I'm a 3 phase setup, and that makes the inverter pricing much higher. I also overspecced what I needed. You can't really compare my pricing either as its quite tied to my needs / setup.

If I were to do a full offgrid setup from the start, it would be cheaper. I'll be doing one next year in my Capri plot. Will blog about it when I get further along on the build. House is also going to have underfloor heating, double glazing (with Low-E windows) and be quite green.

Everyones install is going to be different, as you'll base things on your usage - the numbers don't really make sense otherwise - there is zero incentive here to feed back to the grid. It only makes sense to get more panels if you'll be offgrid, as you'll need for consecutive cloudy days in order to keep batteries charged past that 60% discharge value.

There is no running cost per se, its really an infrastructure cost. Once your infrastructure is installed, you start saving money on not paying Eskom (or muni). Again, there is no benefit here for feeding back to the grid (currently).
Assuming you size something to minimize your daytime usage, you'll save by being on a lower KW rate over the month.
You also quickly learn that dishwashers and washing machines should be run during daylight hours as they're free to run when the sun is up (yay solar!).

Currently we've saved about R10,000-R11,500 (depending on how the KW pricing is calculated) in our first complete year.
That would have put us at about 6-7 year to break even on the install cost assuming the price doesn't increase year on year.
I've now doubled my investment (and will still need to spend about 30-40k more on battery to go full offgrid). At current levels, it would take me 13 years to break even. Its most likely going to be closer to 7 years as it doesn't take a genius to see how the pricing is going for electricity. I also have the confidence that my system is going to work even if Eskom doesn't, so thats also a benefit.
Cost wise its still not quite there for most people, but if you can afford it, and have a bill thats > R1500 a month, its looking a lot more reasonable. If your bill is closer to R4000 a month, its a no brainer..

Those are my thoughts on it, I'm sure Arthur and others who have Solar can chip in also.

 

[richjdavies]

Thanks for all in the info lsheed_cn

Just wanted to check the numbers -- so 6274.7kwh generated in the last year (R10,000-R11,500 saved so that's c. R1.60-1.83/kWh) and R130,000 spent; but then you say 6-7 year payback, rather than 11 years? So I'm missing something...? Is it that you spent only around R70,000 getting the generator stuff in, but the rest on off-grid, which is not a financial decision?

-- the reason I ask is that I've been working these numbers myself for a number of years in a number of different situations (from off-grid mobile stations in Kenya, to community wind-power in India) but for going off-grid in SA I can't get a return >8% whenever I do the 'math'... even with price increases.

PS - I am involved with homebug, but I don't get paid... - it's the 'energy savings' bit that got me involved in Homebug, rather than the other way around

 

[Arthur]

I sound like a broken record, but just want to point out again that the financial justification should not be seen only in terms of the grid electricity price saving.

lsheed_cn's house has an increased market value now that it has solar pv. Were he to sell it today he would probably recover his entire investment. On the other hand, expenditure ordinary grid-power is gone, over, irrecoverable.

In other words, what he has really done is convert future consumption into a capital asset. No solar pv means the future consumption is entirely depleted on use; a capital asset can be liquidated. A major difference that changes the numbers game dramatically.

 

[ToxicBunny]

I sound like a broken record, but just want to point out again that the financial justification should not be seen only in terms of the grid electricity price saving.

lsheed_cn's house has an increased market value now that it has solar pv. Were he to sell it today he would probably recover his entire investment. On the other hand, expenditure ordinary grid-power is gone, over, irrecoverable.

In other words, what he has really done is convert future consumption into a capital asset. No solar pv means the future consumption is entirely depleted on use; a capital asset can be liquidated. A major difference that changes the numbers game dramatically.

That logic only works in certain areas and certain segments of the market.

At the lower end of the market, the investment in Solar is not necessarily going to reflect in the value of the house, or at least not the entire value of the investment... it might add R50k to the price of the house.

 

[itareanlnotani]

Thanks for all in the info lsheed_cn

Just wanted to check the numbers -- so 6274.7kwh generated in the last year (R10,000-R11,500 saved so that's c. R1.60-1.83/kWh) and R130,000 spent; but then you say 6-7 year payback, rather than 11 years? So I'm missing something...? Is it that you spent only around R70,000 getting the generator stuff in, but the rest on off-grid, which is not a financial decision?

-- the reason I ask is that I've been working these numbers myself for a number of years in a number of different situations (from off-grid mobile stations in Kenya, to community wind-power in India) but for going off-grid in SA I can't get a return >8% whenever I do the 'math'... even with price increases.

PS - I am involved with homebug, but I don't get paid... - it's the 'energy savings' bit that got me involved in Homebug, rather than the other way around

My initial investment is about 70k odd, so 7years @ 10k

6274 x R1.56 = 9787. Rounded that up to 10k. A percentage of that would have put us into the 600kw/month bracket, which is billed at R1.86, so would have been somewhere between R10,000 - R11,500, depending on that. I could work it out accurately by looking at the bills / time periods, but the difference doesn't amount to enough to waste my time on it. Time is money ek se!

I've subsequently spent another 75k on inverters+batteries (bought on tuesday) to go partially offgrid. That will increase my payback time on investment to 13 years at current rates. Again, Eskom pricing is going up, so that will likely be closer to a 6-7 year payback/return on investment given the historical rates of increase we've been seeing the last 5 years. If you think that electrical pricing isn't going to continue to rise year on year from now on, I have a bridge to sell you

For me its not primarily a financial decision - its more about having a stable electrical supply. I have a number of computers in the house doing various things, and I prefer them to be able to run without outages. I treat it more as a learning curve for the future.

As I've repeated a number of times, I'm doing a house build over in Capri, and will be going completely offgrid there.

lsheed_cn's house has an increased market value now that it has solar pv. Were he to sell it today he would probably recover his entire investment. On the other hand, expenditure ordinary grid-power is gone, over, irrecoverable.

It does, but should I sell up here, I'll probably move my system elsewhere if the buyer doesn't want to pay for it. Its quite easily moveable - install took a few hours, complete removal would take about a day or so to put things back to pre-install status.
Its a moveable capital asset.

 

[Arthur]

Yep. My system is primarily for stable power. Not ROI. Still, ROI is better than commonly perceived, especially of you can fund it off 'spare' or low-interest capital rather than after-tax income.

It's a hazy day with complete cloud at altitude (no blue). But currently exporting 7.6kW. System loss through conversion and transmission (arrays are some distance from MPPTs and inverter) is just under 9%.

 

[richjdavies]

Thanks for the info-- sounds about right.

I agree about the moving house point as well. No-one asks you what bulbs they get with the house when they buy it, let alone asking what efficiency category your geyser is. So I can't imagine in reality a house would be worth more or less with a solar-system. I've seen lots of houses in SA just get bulldozed as soon as they are bought, so I'm not sure even the fabric of the house is worth that much... As lsheed says -- if the buyer doesn't want to pay for it -- then they can just take it with him!

With the load-shedding, I think we all need to invite ourselves round to lsheen's house to watch the rugby this weekend... I didn't factor that into my calculations

(I left my Wales shirt back in Wales, honest

 

[Arthur]

Thanks for the info-- sounds about right.

I agree about the moving house point as well. No-one asks you what bulbs they get with the house when they buy it, let alone asking what efficiency category your geyser is. So I can't imagine in reality a house would be worth more or less with a solar-system. I've seen lots of houses in SA just get bulldozed as soon as they are bought, so I'm not sure even the fabric of the house is worth that much... As lsheed says -- if the buyer doesn't want to pay for it -- then they can just take it with him!

With the load-shedding, I think we all need to invite ourselves round to lsheen's house to watch the rugby this weekend... I didn't factor that into my calculations

(I left my Wales shirt back in Wales, honest

It depends. I know two people with PV who've sold houses. In both cases they had a price with and without the installed PV, and in both cases the buyers paid were very happy to the extra R150K-ish for the PV. It's just one selling price for the house, of course, not separately split out in the Sale Agmnt.

 

[richjdavies]

in both cases the buyers paid were very happy to the extra R150K-ish for the PV

That is very interesting...
I guess there is certainly the point that it the new buyer gets the benefit of it without any of the hassle -- i.e. it's already done and is happening and probably he can borrow on his mortgage against it -- so it is relatively cheap money.

Certainly when you can say to a buyer -- pay me R150k for it - and save yourself R2000/month, or don't and I'll take it with me... then it's a very compelling offer to a buyer.

Think you've convinced me

 

[Jola]

What would a +/- 80w, 12 Volt solar panel cost nowadays.

And where in Joburg could one get reasonable quality panels ?

 

[Nerfherder]

It depends. I know two people with PV who've sold houses. In both cases they had a price with and without the installed PV, and in both cases the buyers paid were very happy to the extra R150K-ish for the PV. It's just one selling price for the house, of course, not separately split out in the Sale Agmnt.

Its really great to just get it all installed with the house. I would definitely see the value in getting a house with any kind of Solar set up already.

Assuming its actual value though.... if the setup is worth 100k and they have costed the house at 500k more that is not worth it.

 

[Arthur]

Of course not. I'm not speaking of capital appreciation. Just recovery.

Many buyers in the mid market and higher would happily add R200K (say) to their bond for an existing working PV system.

 

[itareanlnotani]

With the load-shedding, I think we all need to invite ourselves round to lsheed's house to watch the rugby this weekend... I didn't factor that into my calculations

Although I do have a 120inch projector screen and full HD projector setup, I don't have DSTV.
On the other hand I do have 30TB+ of movies & TV though available via Plex...

In other news, the Victron battery inverters are mounted underneath my existing grid tied solar setup now. I got that done yesterday on my ownsome. This morning got the batteries hooked up, and am getting ready for the 3 phase side of things; need to run cables from the front of the house to the Eskom side, then terminate the existing cables to the front at the DB side so that the house is effectively on its own mini grid.

The Victron's need a firmware update for me to use them, so waiting on that from Ex-Solar or Victron (whomever replies first).

Electrician and builder are busy having fun running the 3 phase wiring and conduit (I don't enjoy making holes and running around the ceiling, so outsourced that ), and this time around I have remembered to run a network cable to the back also, which means I can finally do some monitoring from the correct end.


Some photos:

 

[Arthur]

Glad you remembered the network cable.

 

[itareanlnotani]

Me too, I want to move all the server equipment to the back of the house!

Makes more sense to have all my expensive equipment in on a shelf above the batteries which totally aren't flammable
Note to self, check household insurance policy hahahaahaha.

 

[Arthur]

The "Utilities Room" that my inverter and batts are in is unventilated. It's time I got some sort of a fan to let hot air exit. High temps are not nice for batteries. About to surf some sites to see what's available.