Solar panels on a whole house

maumau

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Aug 13, 2009
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#41
you need to do an electricity audit - figure out where and how you can cut down
Maybe I'll get the electricity monitor.

Thing is I don't even use the oven much and stopped baking bread because it needs 250 degrees and bakes for an hour. Hob is gas, so yes that monitor's a good idea.
 

isie

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#42
Maybe I'll get the electricity monitor.

Thing is I don't even use the oven much and stopped baking bread because it needs 250 degrees and bakes for an hour. Hob is gas, so yes that monitor's a good idea.
you on prepaid so you can do pretty good rough calculations - just check the credit how many units you use per day.

that what i do so got a good idea on where to cut down and when to set geyser timer etc
I have 2 geysers 1 solar and 1 Electric only - i think i got my time settings down - once i can afford it im converting the other one to solar and i will not save a bucket load as it will only save the times we have later showers but might knock of mayybe on average 2-5KW a day
 

signates

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#43
You can also start with an energy audit by creating a spreadsheet listing all your appliances, the wattage and daily time it's used. It should give you a good idea on what is using the most electricity.
 

cbrunsdonza

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#44
Is your calculator broken?

The conversion kit for a retrofit setup to an existing geyser is 10k, even less on smaller geyser units.

If it saves you R500 a month (which it should do easily) then it's not even two years before the costs are covered and it starts paying for it's investment.
Never said retrofit, said solar geyser which can easily cost R35K for a 200L for a quality unit. Labour, plumbing, electrical are all things to consider.

There is no generic answer to ROI as it is based on current and short term usage patterns.

A small RDP low pressure unit will work for some, a larger high pressure evacuated tube unit for othes.
 

maumau

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#45
You can also start with an energy audit by creating a spreadsheet listing all your appliances, the wattage and daily time it's used. It should give you a good idea on what is using the most electricity.
Hmm, that would definitely help.

Tks @isie will have to pay closer attention to that meter :)
 

SauRoNZA

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#46
Never said retrofit, said solar geyser which can easily cost R35K for a 200L for a quality unit. Labour, plumbing, electrical are all things to consider.

There is no generic answer to ROI as it is based on current and short term usage patterns.

A small RDP low pressure unit will work for some, a larger high pressure evacuated tube unit for othes.
I think prices have changed a whole lot.

Those all-in-one units are around 20k now for a 200l.

But yes it does depend entirely on application.
 

pacmanmb

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Oct 17, 2018
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#47
Not the case - just spent R80k and totally off the grid - just about - and with that run 2 heat pumps/pool/borehole off a 5kva inverter - 8 bedroom house
 

lsheed_cn

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#49
Brief guesstimate for you -

5kw panels - 1400 / 250w panel. +-10kw - 40kw/day winter - summer output - R28k
5kw /48v non approved inverter eg axpert R13k
20kw lithium battery (4 x SMI~LE5 5.7kw / 42k each) R170k
fittings cabling +-R5k
installation/signoff - 30k

Total = 220k- 250k for a fully offgrid house using retail pricing.

Spend some additional money on Gas cooking, solar hot water, led lighting, variable speed pool pump - 50k, and you would get away with half the battery i.e 10kw -which is the major cost above.
 

pacmanmb

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Oct 17, 2018
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#50
You need to calculate your usage first to determine the best size for your system.

Get an energy monitoring tool to track your usage over a few weeks. I have an efergy home electricity monitor that's tracks my current usage and peak kw.

I use about 900kwh per month with peak power of 12kw.

I would also first look at getting an evacuated tube solar panel for your geysers.
Hi there,

With which company did you do this? And how is your feedback?
German solar - or ebright solar - not joking about using about 2kw a day now just to keep batteries topped up on bad weather days
 

calypso

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Feb 10, 2009
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#53
Brief guesstimate for you -

5kw panels - 1400 / 250w panel. +-10kw - 40kw/day winter - summer output - R28k
5kw /48v non approved inverter eg axpert R13k
20kw lithium battery (4 x SMI~LE5 5.7kw / 42k each) R170k
fittings cabling +-R5k
installation/signoff - 30k

Total = 220k- 250k for a fully offgrid house using retail pricing.

Spend some additional money on Gas cooking, solar hot water, led lighting, variable speed pool pump - 50k, and you would get away with half the battery i.e 10kw -which is the major cost above.
Jeeper, winter really that bad? Only 2kw per day out of a 5kw system? Not saying that I dont believe you, just didnt think the swings were so high between seasons.
 

chrisc

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Aug 14, 2008
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#54
In Montagu, I have 3 sqm of solar water tubes feeding into a 200 litre tank. Only on 3 days has the water temperature dropped below 30 deg. In winter it is usually 45 deg, in summer 70 deg

Then there are 12, 3000 watt PV panels and a 12 amp MPPT inverter and 16, 12 volt 105 a/h batteries.

In 2012 the municipality fees for the whole year was R62. Since July this year there is a "connection fee" added to the bill for electricity of R55. So for using no Eskom electricity, there is a R660 annual fee
 

lsheed_cn

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#55
Jeeper, winter really that bad? Only 2kw per day out of a 5kw system? Not saying that I dont believe you, just didnt think the swings were so high between seasons.
Will vary depending on your location. I'm in CPT, thats how it is here in winter.

5KW system 10kw+- in winter (2hrs x 5kw / or roughly 2 full hours of sun over the entire day)
30KW-40KW in summer. (5hrs-7hrs x 5kw / or roughly 5-7 full hours of sun over the entire day)

I'll always recommend to people to size a solar system for winter needs.
Panels are cheap, which means that generation is cheap. Storage isn't.

If Eskom allowed grid feedback credits we could send the poor electricity without too much issue in summer just from residential installs with a sufficient user base. That would mean less strain on infrastructure, less need to run dirty coal plants etc etc. Could easily be done without spending a rand, just some smart legislation.
Solar could run pretty much the entire day, excess could be fed into hydro, and the hydro used for early evening.
Wind and other smaller generation can then cater for the evening low baseload requirements.

Instead, solar users are called thieves, and stigmatized, and pricing is set the discourage solar.
 

isie

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Jan 16, 2010
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9,717
#56
Will vary depending on your location. I'm in CPT, thats how it is here in winter.

5KW system 10kw+- in winter (2hrs x 5kw / or roughly 2 full hours of sun over the entire day)
30KW-40KW in summer. (5hrs-7hrs x 5kw / or roughly 5-7 full hours of sun over the entire day)

I'll always recommend to people to size a solar system for winter needs.
Panels are cheap, which means that generation is cheap. Storage isn't.

If Eskom allowed grid feedback credits we could send the poor electricity without too much issue in summer just from residential installs with a sufficient user base. That would mean less strain on infrastructure, less need to run dirty coal plants etc etc. Could easily be done without spending a rand, just some smart legislation.
Solar could run pretty much the entire day, excess could be fed into hydro, and the hydro used for early evening.
Wind and other smaller generation can then cater for the evening low baseload requirements.

Instead, solar users are called thieves, and stigmatized, and pricing is set the discourage solar.
Correct - most of their equipment - smart meters already can cater for this - even on prepaid they can just program it to credit the user for excess energy sent to the grid.
 

BuckRogers

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Jan 17, 2012
Messages
259
#57
Is it possible to have a system without storage?
Your load will then be covered by the solar panels and topped up by eskom when the load exceeds generation.
In the event of generating more that required, can it just be forfeited ?
We pay R2.55 kw/h in cape town on the top tier. There are also threats of another 15% increase. Will a solar kw/h come in at less than that ?
 

oober

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Apr 3, 2005
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#58
Currently using abour R50-R100 worth of power a month. Switched to prepaid to not have to pay the crazy R500 connection charges. Our price per unit is R1.43 I think. For me it's not so much about ROI but being unaffected by power outages.
 

lsheed_cn

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#59
Is it possible to have a system without storage?
Your load will then be covered by the solar panels and topped up by eskom when the load exceeds generation.
In the event of generating more that required, can it just be forfeited ?
We pay R2.55 kw/h in cape town on the top tier. There are also threats of another 15% increase. Will a solar kw/h come in at less than that ?
Solar without storage is _far_ cheaper than that per KW.
Solar _with_ storage is already cheaper than that, but not by much.
 
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