Energy talk...

Over the last week, my solar battery has been running the whole house. I arrived home from 9 days holiday on Thurs 15th, so you can see the change in usage from then. I've had the air/con going most of the time during the day since Thurs and the solar and battery is still providing more than I use. The graph shows usage from 8th-14th, today. The yellow line shows how much solar power the panels are producing, the blue line shows the load, and the red line shows how much is feeding into the grid. A brown line would show grid consumption, but I haven't consumed any from the grid this week.

Thats awesome. I'm going to upgrade the solar on the new place I'm moving to to get that kind of result.
I'm giving heavy consideration to getting a battery as well. But not sure if the economics are favorable enough yet ...

Overcast day, system fully charged at 11:25 am, solar hot water electric boost element turned itself on, then the dam water pump turned on 20 mins later as there was still more power than enough. Mother in law then turned on her AC and the dam pump turned itself off about 1 hr later. Hot water was over 80 deg, so it switched off and then 20 mins later the dam pump started up again, as there was still too much power. Still no sun, now its 5:30 pm and the system is still in float (fully charged), and the dam pump is still running. Got over 29 kwh today, and the system can produce more than that, we just cant use it. One disadvantage of being off grid is that u cant feed excess power back into the grid, u need to use it as its generated. The main system can theoretically generate over 100 kwh per day, but if we ever got to that, it would be bad management on our part to have taken the battery pak (2,600 amp hrs at 48 volts submarine battery, 124 kwh, $25 k worth 10 years ago), down that low. The main use for so much solar is for overcast weather so we don't need to start a generator (12kva water cooled diesel, or 8.5 kva air cooled Honda petrol/lpgas), which is a money drain we can do without.

If the sun goes away we could be in a bit of trouble, but while there is still light, full sun isn't needed, all is well.

Just installed System number 8, a small 12 v system with a 1 kw inverter and 100 amp hr battery on the caravan that I use to uncap frames and spin honey out in, near the apiary.





The size of a battery is measured in vaults (V). Most small batteries are about 1.5 vaults.

Perhaps Ive assumed that the readers of the forum know more than they actually do. Well, lets remedy that issue.

The regulator/s on a solar system will take care of dealing with the excess power produced. Some are series types that just limit the amount of energy they supply to the battery, whilst others are smarter and can switch on various loads to make use of the energy that would otherwise be 'lost', (Note, not wasted as it hasn't done anything). A further type of regulator is the shunt, or diversion regulator. These are used on stand alone wind generators and hydro turbines to keep a constant load on the machines and prevent a 'run away', which would happen on no load. The energy is dissipated in some form of load, a resistor or water element etc.

The upshot is that you don't need "to use all the power that you generate." The regulator will automatically assign max power to charge the battery, then 'regulate' the rest. Our regulators, 3 of them on the main system, have limited 'smarts' in them and can be programmed to turn on a relay when certain parameters are met. For instance: When the battery's are full, the relay is switched on and that puts power from the inverter into the solar hot water systems electric element, to give it an extra boost. After a further time period and if the battery voltage is still at the float, or full charge level, another relay switches on to run a 1 hp pump that pumps water from the dam to a 45 kl header tank, giving about 400 kpa pressure to the farm for irrigation, without needing the pump. The tank acts as a store of energy, like a big, wet battery. This is also good for fire fighting, as if something happens, the water is there instantly, no pumps needed.

If after a further time period, 10 mins I think, the battery voltage is still at the float level, another relay switches on, running another 240 v pump, this time pumping to another 45 kl header tank, pumping from the rainwater tanks at the house/shed (depending on which valve is on at the time), and giving 400 Kpa water pressure to the houses, without the need for a pump to run after dark. Once again, the tank stores excess energy, like a big wet battery.

The switching can be programmed to happen on various events, current limits, voltage limits, sun intensity, time and so on. I am using a simple voltage limit.

Obviously, at some stage, both tanks are full and the pumps have switched themselves off on the pressure switch, the hot water system is boosted and the element is switched off on its thermostat and there is still sunshine. What happens ?

The regulator turns itself off and disconnects the solar array from the battery, thereby stopping the charge. (There is still a little bypasses modern regulators as they don't completely shut off like old models with relays did). The electrons released by the sun just stop flowing, as there is no complete circuit to conduct them and it all stops.

So you don't need to match your load to the suns output, the regulator will do that for you.

Modern regulators are of different types, PWM, MPPT etc, but almost all of them can do more tricks than just regulate the battery's. They can be programmed to operate security lighting after dark, time-switched if needed, as well as turn the loads on or off according to battery charge level etc.

Hope the above makes sense. I don't mind expanding on a subject if the members wish it.






One example of high vaultage is the San Andreas Vault.


One not mi vault = 0.001 vault