Best Of
Re: Undercharged Battery Bank? Low Specific Gravity
Estragon: The panels are 2-3 feet from the CC with 6AWG cable. I measured the voltage coming into the CC at the combiners: 40.3 volts. It has been overcast/snowing the past two days however. Probably won't be full sun until 2 days from now.
BB: I will eventually get the panels and CC upgraded, but given the costs, I'm looking for short-term solution. Using your figures, if I remove one string from the bank, I can get a 10%+ rate of charge with one additional panel giving me a 1,920 watt array. I can run my house on the two strings. The bank I had before was 625AH and that was adequate. 24 volts would also be ok for that size bank, agreed?
Someone suggested that I charge the batteries one string at a time to get them to full charge. That seems like a good suggestion. After that I could remove one of the strings. If I do that, I would move the 4 batteries to my storage shed for a stable ambient temp. I could keep fully charged batteries in storage for a few months, I believe. What do you think?
Skipmca
Re: Victron disconnect quirk causing temperature sensor failure?
Saipro
Re: Retired, Want to Go Off Grid Because of High Cost of Electricity
NANOcontrol
Grounding
sandebagger2u
Fridge is surge overloading inverter
I need to come up with a plan around this error. What I have in mind is getting a UPS for a computer which has a battery backup in it good for 30 mins. When the fridge first kicks on, I want it to utilize the juice inside the UPS for its surge instead of the inverter. Anyone have any suggestions on which ones do this? I know not all UPS's allow you take a pull off the batteries if it has power coming in. Or maybe there's a better idea someone has to work around this issue?
flighthouse
Dipping my toe into solar energy.
Hi all.Been lurking for awhile.This site is a wealth of info.I have a small system that's been running about a year and a half.So far so good.I have 4 100watt panels wired in parallel feeding Tristar 45 charging 2 12 volt 50 AH agm batteries wired in parallel. A suresine 300 watt inverter gets some use.I now know these batteries should be 6 volt wired in series.I use max 500WH in the summer and almost nothing in winter--3 led lights and occasionally a trickle charger for lawn mower battery.Looks like I have enough charging capacity to upgrade to 6 volt 225 AH batteries.A couple days last summer my batteries got down to 12.2 volts--the reason for battery upgrade.Will my system work year round?.Do I have to exercise the batteries during winter or will they be happy just sitting with almost no DOD other than self discharge? I'm at 42 degrees latitude and the panels are angled at 22 degrees--roof pitch.I know the angle isn't good for winter but it is ok for summer when most of the energy will be used.I'm running a 12 volt cooler that uses 464 WH per day--manufacturer's number, not measured and 3 10 watt led lights,sometimes a small radio and a phone charger.If all goes well we would like to build a larger system.Thanks in advance for all opinions.
cheers kent
Kenth
Re: PWM that can 24v(28+v) input with 12v(14+v) output
Generally, if your panels are "12 volt" rated (Vmp~17,5-18,5) volts, that is the "accepted" standard for connecting a PWM controller to a 12 volt Lead Acid battery bank.
Long wiring (too small of diameter), very hot weather with cool battery bank, etc. (Vmp falls as temperature rise, Lead Acid battery charging voltage rises as they get cold) and the voltage drop from hot panels / long wire run from array to cool battery bank (higher voltages needed)--You can run into reduced charging current in Hot weather.
In cold weather, Vmp-array rises--But for a PWM controller that "extra/free" energy (power=Voltage*Current, rising V = rising available power) is lost.
A MPPT based charge controller is like an automatic transmission between the solar array and battery bank. It can run the solar array at "optimum Vmp and Imp" and charge the battery bank at "optimum Vbatt and Ibatt".
If, for example, you put 2x "12 volt" panels in series with an MPPT charge controller, then in Hot Weather, Vmp-array-hot is still way higher voltage than you need to charge/equalize your battery bank. And in subfreezing weather, the increase in Vmp-array (~10-20% increase in voltage), the MPPT controller can supply that "extra free power" to the battery bank charging/running your loads).
In the old days when solar panels were over $10 a Watt and golf cart batteries--Optimizing a system to save on solar panel costs made sense.
Today, batteries are 2x or more expensive, and solar panels (large wattage) less than $1 per Watt... So optimizing the battery charging/loading conditions for longer battery life makes sense--And throwing cheap panels at your system to keep your expensive batteries "happy" makes sense today.
-Bill
BB.
Re: Wildfires are nice for Solar Business
Dave Angelini
Re: Solar Generator batteries losing battery charge
mcgivor