Energy Products

How do you get your PW's to charge to 100%

I have two recently installed PW's. I am not getting very much sun on my panels so during the day the PW's only charge from 5% reserve to about 35% with the house using Solar for power, and the rest charging the PW's. After 4 pm with only 35% the PW's run the house for about 4 hours, discharged to 5% by about 8pm. How do I get the PW's to charge to 100% from the grid during non peak hours. Ideally I would like the PW's to charge while we sleep. The grid would be running the house, and charging the PW's.

Comments

  • If you're in the U.S., and you accepted grants or the Fed tax credit, it's unlikely you're allowed to charge from the grid. It's often one of the agreed-to conditions for getting the money. Some utilities disallow it as well.

    It's very rare to be able to charge from the grid in the States, but common in some other countries, like Australia and the UK.
  • > @RLSolar said:
    > I have two recently installed PW's. I am not getting very much sun on my panels so during the day the PW's only charge from 5% reserve to about 35% with the house using Solar for power, and the rest charging the PW's.

    "with the house using Solar for power, and the rest charging the PW's."...

    is why you are only charging your batteries to 35%. You have it set to either "Self-Powered" or "Balanced". In these modes solar first goes to the house and only excess solar goes to the battery. Your house is using a lot of solar so there is not enough additional solar to fully charge your batteries. Set you PW gateway to "Cost-Savings". In this mode all solar first goes to the batteries until they are charged. After they are charged will the solar then go to your house with excess going to the grid.
  • > @gregbrew_98470014 said:
    > It's very rare to be able to charge from the grid in the States, but common in some other countries, like Australia and the UK.

    The only way to charge from the grid in the US in the scenario you described is if you do not have solar at all or if "Storm Watch" is initiated by the National Weather Service
  • @Dodgerking - Thanks! I hadn't thought about it in a while, but cost savings is a better choice during the winter when you don't generate enough solar to power the house for the day. I switched to cost savings an hour ago. Note that it didn't change how it charged immediately. Checking back an hour later and it's using 100% solar to charge the Powerwall, and using the grid to power the house as I'm in an off-peak time right now. My expectation is when peak hits, it will stop using the grid and power from the solar/PW combo. I should have done this a few months ago!
  • Yes. Once peak time hits then your house will run off battery only. If you want to save the battery because it didn't charge enough, you can take it off cost savings during the peak hours and use backup only. Since you didn't switch it to cost savings until later, and you have two batteries to charge, your batteries still may not charge fully today. Leave it on cost savings all day tomorrow to see if your batteries to get fully charged and by what time.
  • Is cost saving setting really a good setting? On the cost saving setting yesterday, my two PW's charged to 100%. It took most of the day so I was on the grid through the night until 4 pm. At 4 pm the PW's ran the house until 9 pm with 65% charge left and then the grid came on. Is that the best use of energy. So yesterday I was using the grid 19 hours, and battery 5 hours with 65% of battery remaining. Today, I went back to self powered and set the battery to 50%. It seems to me that would use battery for prime, some battery for other, charge the battery to 100% with solar, and still have some solar to run the house.

    Am I missing something,

    Thanks
  • Cost savings will use the grid more than the others, but in your case and this time of year it is the only setting that will allow you to fully charge your battery AND not use any grid power during your peak hours. Self Powered uses the grid the least of all the settings, but because of the time of year and the amount of energy you use, your battery appears to drain too much and you are not able to fully charge them the next day. If I were you I would use cost savings in the winter, then change it to self powered or balanced in the summer
  • Thanks, so what I am doing is setting the Batteries to 50%. During the day I should have enough solar power to charge the batteries to 100%, and still have some solar for the house, and I am able to use the batteries from 100% to 50% to run the house during peak hours. Trying to find the "sweet spot" for battery charge to 100% and full backup energy during peak hours.

    Thanks for your input
  • @RLSolar - Also it's easy to experiment. There are a lot of variables between systems. If you're in New Mexico, have no clouds or rain, a very large solar array, perhaps you don't need Cost savings mode and Self-Powered is better for you.

    Many of us have more limitations (much less sun in Winter, smaller solar array) so that there is not enough solar power generated in a day to power the house with the solar/Powerwall combination. The utilities in California also limit our solar design as energy production is not supposed to be positive over a year's time. That means Winter production for us is always going to be less than the house needs.
  • Playing around with the settings is what pretty much what everyone has to do. Everyone's situation is different and there is no one size fits all suggestion. Just keep experimenting and you will find the best settings for your needs, situation, and concerns. You may continue to play around each season and find that each season may require different settings for your situation
  • I like Cost Savings mode because it maximizes the efficiency of the system. You can view the grid like a battery in that you send energy to it when you have excess and you draw energy from it when needed. Excess energy builds up in the form of $ credits with the utility that you draw down as needed. The grid is 100% efficient in that regard. Comparatively, the Powerwalls, due to the presence of the inverters, are only 90% efficient in their turn around of energy. Because of this efficiency difference it takes more power to recharge the Powerwalls than it does to pay back the grid. It follows that it is less efficient to draw from the powerwalls in off peak than it is to draw from the grid in off peak. The less charging you need to do, the sooner you begin exporting to the grid. Maximize the use and repayment of the grid during off peak, maximize exports to the grid during peak, and maximize use of the powerwalls during peak when the grid most expensive. This minimizes the amount of recharging needed while accomplishing the load shifting that the Powerwalls do so well. Cost Savings mode seems to do this best.
  • In areas that do not have tiered pricing, like here in the northeast, self-powered seems to be the best setting to just use as much sun when you have it and the grid when you don’t.
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