Views on Self Consumption

[PVMatt]

There has been alot of talk around self consumption,

From my understanding the products available are not certified for example the new sunny island expected to market next year

I also hear about Victrons products being retrofitted and not being questioned about certification.

Can any one shed light on this subject as I am looking into starting a business based purely on retrofitting these type of products,creating a network of qualified MCS installers to install over the UK.

John

 

[Gavin A]

would you like us to write your business plan for you as well?

 

[Worcester]

Opinion - It's beacue the EU targets are wrong - They are targets about generations not C02 redcutions "Produce x% of electricity from sustainable sources" just leads a drive to produce more and more and then consume it....

 

[moospark]

Self consumption? Constantly over the top in my opinion.

 

[telectrix]

biting your fingernails is one thing, but eating your own arm is beyond belief.

 

[sean_ork]

unless you live off grid, those ''store it during the day, use it during the night'' products just don't make economic sense - until the storage media (the batteries) become far cheaper and far more efficient such devices will have very limited use within a typical domestic environment

 

[PVMatt]

With the increase of awareness of "Rolling Black outs" that are expected within the next few years, will people look to invest in energy storage. There is a great expectation in this market to grow. For self consumption you will not require a great deal of storage. Looking at the likes or P1 and SMA bringing energy storage products with a between 2 and 4 KW/h worth or storage the initial upfront material cost could be as little as double the amount of a standard PV system

 

[SolarCity]

Yeah, but what about the maintenance? How much life can you expect to get from the batteries?

 

[FB.]

With the increase of awareness of "Rolling Black outs" that are expected within the next few years, will people look to invest in energy storage......
..... products with a between 2 and 4 KW/h worth......

Ignoring what PV produces, my average annual electricity consumption is around 3300kWh (and my 3.7kWp array produces a similar amount).
My usage therefore averages 9kWh per day through the year.
Call it daily usage of 9kWh in spring and autumn; probably 4kWh in summer and 14kWh in winter.

My average daily PV generation in summer is about 14kWh which is plenty to recharge batteries.

In spring and autumn my generation is about 9kWh per day; roughly matching my requirements. However, a run of several dull days (low pressure, weather front) could see me generating just 3-4kWh per day and having to ration power until the sun came out again.

Winter is the really problematic one, with only 4kWh per day average solar generation but 14kWh daily average usage. I'd have to make some serious cutbacks and would have real problems during a week of heavy cloud cover when I might generate only 1-2kWh per day.


The easiest thing would be for me to get one of my two long-runtime petrol generators out of my workshop and run my essential power needs off that (SDMO SH3000 and Pramac ES4000).

 

[PVMatt]

Yeah, but what about the maintenance? How much life can you expect to get from the batteries?

Battery life is dependant on the way they are used. I have seen batteries last as long as 10 years, obviously it will be more likely closer to 5 as the constant cycling of the batteries will 1reduce life. If you use Gel/AGM batteries then you will be virtually maintenance free. Would customers pay around 10K for a 4Kw install which will include battery storage?

 

[Marvo]

What's the carbon footprint of these systems? Surely with battery replacement every 4-5 years they're going to be horrific.

 

[Worcester]

@FB sums up the problem well, it's most likely winter when the blackouts will occur and they won't have had enough sun to replenish them.

There's another thread running somewhere on here about someone that has one of these systems installed, and that even STARTS the day by topping up from the grid...

The question is are you looking at its functionality as a big UPS topped up by PV as well as grid? Or are you looking at a system to store excess generation and then feed the property at night? If you do the latter, you can't have the former as the storage will be depleted by the morning and so can't provide a UPS capability..... They are mutually exclusive objectives. -So which are you a proponent of?

I'm not sure a household UPS stacks up, especially when you can buy a cheap generator and even install an automatic switchover and start up for a fraction of the price of a 'UPS'.

As for self consumption, - it's what happens on all our commercial installs, rarely do they export anything because their consumption is well over the generation.

 

[Worcester]

Here's the link : http://www.electriciansforums.co.uk...ght-sun-anyone-seens-before-2.html#post838634

 

[mdovey]

The question is are you looking at its functionality as a big UPS topped up by PV as well as grid? Or are you looking at a system to store excess generation and then feed the property at night? If you do the latter, you can't have the former as the storage will be depleted by the morning and so can't provide a UPS capability..... They are mutually exclusive objectives.

The Sunny Backup system will only run the house off the batteries until they reach 50% at which point it will switch the house to using the mains grid. It will only drain the batteries beyond 50% if there is a power failure (I think the actual cut off point can be configured). This gives you both self consumption and battery reserve for providing a UPS capability. Of course you have to get the battery sizing right - although unlike panels it is very easy to add additional batteries so it is probably better to err on undersizing at the beginning.

However, the economic and ecological arguments are weak. Last time I did some google, I think the retail price for a Sunny Backup plus batteries was in the region of 5K. The average electricity bill is 500 per annum, so assuming that you managed to reduce your bill to 0, you'd be looking at a 10 year pay back time. In practice, the solar panels themselves should have reduced the bill already and self consumption would probably at best only halve the bill.

As others have pointed out that battery life will be 5-10 years, so you will need to replace the batteries before the system has paid for itself. Battery technology is always improving but if you want to take advantage of whatever the best battery technology is in 5 years time you'll probably need to replace the entire system (no-one today can build a charger guaranteed to work with batteries which do not yet exist!).

It may change with future technologies but batteries are not particularly ecological to produce and are typically not recyclable when they are past their life, so any green credentials in self consumption will be offset by the ecological impact of the batteries themselves.

Matthew

 

[PVMatt]

@FB sums up the problem well, it's most likely winter when the blackouts will occur and they won't have had enough sun to replenish them.

There's another thread running somewhere on here about someone that has one of these systems installed, and that even STARTS the day by topping up from the grid...

The question is are you looking at its functionality as a big UPS topped up by PV as well as grid? Or are you looking at a system to store excess generation and then feed the property at night? If you do the latter, you can't have the former as the storage will be depleted by the morning and so can't provide a UPS capability..... They are mutually exclusive objectives. -So which are you a proponent of?

I'm not sure a household UPS stacks up, especially when you can buy a cheap generator and even install an automatic switchover and start up for a fraction of the price of a 'UPS'.

As for self consumption, - it's what happens on all our commercial installs, rarely do they export anything because their consumption is well over the generation.

From the new Victron firm ware the idea of their hub system is to run store PV through out the day, the inverter charger will detect if there is generation, if there is not generation it will go on to battery storage until the point the batterys are discharged to 50%, then the load draws from the grid. The next day the mutliplus will detect generation and at that point will charge the batteries to be used that night. Because they are at 50% and only drawing when pv is producing you will not damage your batteries. I am not sure if your able to manually charge batteries from the grid if there is maybe 2/3 days of poor sun light.