Renewable Energy generators' Journal
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Wednesday, May 16, 2012
4:32PM
Variable performance over recent weeks.
Many days with overcast skies and rain, and typical yeilds of 1.5 KWh or less, with two days down to 0.6.
With the fairing up of the weather at the end of last week 4.3 KWSh was recorded on Firady and 4.0 on Saturday, comfortably in excess of the 1.8 KWh daily consumption with the surplus bringing about rapid recharging of the batteries - the batteries reached the absorb point briefly on Friday and reached the Float point on Saturday.
Completed the setting up and fettling of the solar hot water system in the old central library in Bermondsey. Embaraasingly we ran out of armourflex and were left with some parts of the pipe run uninsulated until further packs were delivered. This has a significant effect. What happens is that this results in a slug of cold water which is moved around as the pump runs, and one gets a reduction in panel temperature co-incident with the tank temperature starting to rise and often resulting in the controler stopping the pump as the difference has fallen below the minimum in the control settings. With all insulation now in place the pump was observed to run more or less continuously and the panel and tank temperatures were creeping upwards.
To take advantage I increased the cut off point for the tank temperature to 70C. AS the tank is a thermal store rather than one where the water is drawn directly, it can be allowed to reach a much higher temperature as there is a thermostatic mixing valve on the output to limit temperature plus all the showers have thermostatic mixers as part of the controls, giving two safety systems between the hot water and a person.
I have also brought the timer function of the controller into use, to inhibit the operation of the backup boiler from around 0810, when the last person is having their morning shower until around 1550, to allow the boiler to bring the store to temperature is required before the first resident gets home from work and wants a hot shower. The intention is to allow the last two showers to cool the top of the tank - it can fall potentially to around 45C before it becomes difficult to have the output water hot enough, and one hopes allows a significant amount of cold water to sink to the base of the store so that the store is most able to absorb heat, especially if the weather is indiffernt.
Thursday, March 29, 2012
Harrow :
March - 45 KWh electrical energy delivered
Bermondsey - 1 Megawatt-Hour electrical energy generated
Saturday, March 24, 2012
10:13PM
3 KWh harvested today.
A pleasing 2:45 in Absorb mode.
A particular pleasure tonight dealing with an inquiry for a solar PV installation knowing that the computer and Internet router were running on solar power, as is the steamer presently cooking my supper.
Thursday, March 22, 2012
10:33PM
Harrow
2.9 KWh today
39 minutes of Absorb time
Very good sun forecast for tomorrow
Goodbye grid,
7:03PM
Harrow.
3 KWh on Monday and Wednesday this week.
Monday, March 19, 2012
Bermondsey
9.95 KW peak power today.
Harrow
3.01 KWh harvested
Sunday, March 11, 2012
10:14PM
Bermondsey
peak power of 7 KW, running around 6 most of the day and 35 KWh produced.
Saturday, March 10, 2012
Bermondsey. 10-03-2012
Climbing to around 4 KW under the overcast sky in the morning
Peak power of 8.5 KW during early afternoon.
Building exporting between 3 and 5 Kilowatts
Thursday, March 8, 2012
Harrow.
Half a kilowatt and it's only 1000.
Around half the consumption is from solar at present. Several days everything runs on the solar supply, with loads being shed after indifferent days to allow the surplus on days like this to bring the battery charge up again.
Generally the cue to return fully to solar is when the log from the controller for the days shows significant time spent in "Absorb" mode, as this the the mode where the last 20 per cent or so of the possible charge is being stored.
Bermondsey
All commissioned, and Monday was reported as producing 5KW at 1000. The system is unusual in having panels horizontal. This is not my choice, but it did keep everything invisible from ground level and allowed things to go obtain planning and listed building consent. The power loss from a flat mounting is offset to some degree by being able to fit more panels into the available space. This gives a payback in poor sun conditions where there is more light coming vertically from scattering in clouds, and there is a greater area of silicon to capture it.
Under poor overcast systems a kilowatt of power has often bee recorded.
Tuesday, February 28, 2012
Commissioning over the weekend was successful - Array wiring all proved out Saturday, tested to the input plugs to go in the inverter, then one link disconnected each array section to leave it in a safe condition as there was a chance there would be work done on sunday adding the remaining ballast blocks.
Returned late Sunday afternoon, restored the links, rechecked the array volatage and polarity, set the inverter to G83 and English and connected everything up.
Self test was successful. System fully commissioned Monday and registered. It wrung 11 KWh out of indifferent sun on Monday and 22 KWh today. At mid day the building was exporting power.
A pleasing conclusion to five weeks work.
Thursday, February 23, 2012
Saturday, February 11, 2012
7:48PM
2.4 Kilowatt hours harvested today
Yesterday a peak current of 26 amps when the sun came out at mid day.
The cold snap is proving a good time for winter solar electricity, with good harvest of over 2 Kilowatt hours on several days during the last fortnight
Sunday, January 15, 2012
10:00PM
Sun conditions excellent.
1.4 KWh received.
Soure of power loss found and corrected - large shrub in garden which shades the west section pruned.
Saturday, January 14, 2012
8:22PM
Even better weather today
1.4 KWh.
Free electricity tonight
12:03AM
Good weather today - clear sky and low temperature.
1.1 KWh harvested
Wednesday, January 4, 2012
Orders just placed for cables switchgear and meter for a 10 KW 3 phase grid connected system.
reviewing quotes for inverts and PV modules.
Doing lots of calculations for roof loadings, wind forces and playing e-mail tennis with structural engineer
Sunday, July 31, 2011
Very little required.
however, mid day current of only 17 amps seemed rather low for a summer day, and inspection showed a number of cell shaded by the brambles. Once the secateurs had done there work a current of 21 amps was recorded.
Cooking lunch with the steamer produced a peak current of 25 amps out of the charge controller, which dropped back to around 21 amps or so. For the first time in around 2 weeks the batteries have had a period of "Absorption" charging rather than "Bulk".
I also nailed an annoying RF interference issue spoiling my enjoyment of radio three. The link from the DC negative to earth has been re-made and the inverter negative cable dressed clear of the actual inverter - it seemed to be prone to picking up interference from the innards of the inverter and forming some sort of feedback loop.
Saturday, June 11, 2011
Very good results so far.
I have not had to buy in energy electrical energys since march
Since the last week in March my little secondary meter unit (an "Efergy" shows
7 KWH for the end of march
45 KWh for April
45 KWh for may
17 so far for June
A total of 114 KWH delivered and used from the sun.
Sunday, April 24, 2011
Took advantage of being at home in the day to do some further investigations.
The Absorb part of the charge process is important. It is responsible both for getting the final lot of charge into the battery and preventing the water in the electrolyte breaking down, giving off hydrogen and both creating a hazard from explosive hydrogen and making the electrolyte excessively acidic to the detriment of battery life.
If the battery spends too short a time on Absorb it will never become fully charged and over the long term sulphation is a possibility.
If the absorb time runs on too long then the battery will be driven into overcharge.
A time limit gives an overall protection from overcharge and can usually be set with the aid of the manufacturer's data sheet or tech support.
The aim is, however to end the absorb stage when the charge current drops below a critical threshold.
in a system such as this there is both charge current and load current to be considered. The load current must not be allowed to mask the charge current and cause the controller to maintain the Absorb voltage past the point where the battery is fully charged.
By connecting and dropping the load it was possible to observe the standing current of around 2 ampere from the daytime base load.
Around 5 amps, the battery is fully charged, and the tracking process starts to introduces sufficient variation in output current that it appears that the charge point may not be detected reliably.
As a trial the cut off current for the Absorb cycle has been set to seven amps, with an overall time limit of 3 hours and this will be observed over the next few weeks.
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