Telsa vs Sigenergy

roadweary

Hi,

Pros and cons of Tesla PW3 vs Signergy 2 x 10 batteries with an 8kw inverter please?

Average 18kwh per day, 6700kwh per year. Lots of aircon and computers/monitors used for a couple that work from home all day.

19 Aiko 515w panels, but 10 of those are North facing so half as efficient as the 9 on the South roof.

Thanks!

sheenas

I work from home and use about 10kwh per day. I have 3 computers going and monitors etc, but no aircon. During the day we tick along at under 500wh with the occasional short spike to 1kw. I know this because I have a shelly power monitor.

You maybe wondering how this affects you. If you don't already, I would a 120a power monitor and clamp it to the power coming into the building. That will allow you understand your energy use profile. Next i would look to understanding how the north/south panels are connected to the current inverter, there are different inverters that handle north/south panel configs better than others.

I suspect you air con is zapping most of that energy and it worth calculating how much storage makes sense for you. 10kwh is a typical. I suspect an 8kw inverter will be over kill. No appliance in my house is over 1.2kw. I don't have electric showers, but not many would try running a shower from battery anyway.

Netexporter

8kW wouldn't be overkill if you wanted off-grid capability, by fitting a gateway, in the case of a power cut. Depends on how reliable your local supply is.

I was impressed by Sigenergy's pro-active management of a potential safety hazard, caused by some installers using the wrong type of cable on the larger capacity units. They paid for inspection and, if necessary correction, of potentially affected installations.

NedS

Very happy with my Tesla PW3 + Gateway.

The Gateway provides full home backup, and the PW3 can deliver 11kW of sustained load. Charge rate is 5kW so it can fully recharge from zero in a 3h cheap rate window.

PW3 is 13.5kWh, all usable 100% DoD (technically it's a 15kWh battery but 1.5kWh is hidden from the user reserved to ensure it meets it's warranty of 80% usable after 10 years)

From watching some videos, I understand the Sigenergy App is more flexible. The Tesla App has two modes of operation, Self Powered and Time-based Control. You pick which suits you best and leave it to get on with it. It's not always easy to force it to do what you want if you're playing the arbitrage game, but for most non-techie users it is probably just fine.

AIUI, the 10kW Sigenergy battery modules are 8.76kWh so you'd get around 17.5kWh with two modules vs 13.5kWh with the Tesla. The Tesla can add further 13.5kWh expansion packs as required.

Is the 13.5kWh PW3 sufficient storage with your average daily use of 18kWh? What tariff do you plan to run, and will you be able to consume the shortfall directly from the grid during cheap rate periods? I can consume up to 45kWh in winter (ASHP), but manage fine with a single 13.5kWh PW3 because we use the Cosy tariff that has 8h of cheap rate spread across 3 cheap rate periods so we can charge/discharge the PW3 3 times per day plus load shift usage into the 3 cheap rate periods. So it very much depends on your intended use case.

The PW3 has 3 MPPT string inputs, so would have no problem handling 9 south facing panels on one string and the 10 north facing panels on another (I have two strings of 9+8 south facing panels). Not sure about the Sigenergy inverter specs.

Netexporter

The car charging module in the Sigenergy is interesting and I'm fairly certain it is V2G ready. It could easily be added later, if EV acquisition is a while off.

roadweary

https://forums.moneysavingexpert.com/discussion/comment/82022319#Comment_82022319

Hi, that's super helpful, my answer perhaps, less so. I just looked at our bill and actually Dec 26th we used 37 kWh! I've requested one of those little smart meter home displays from Ecotricity, our supplier….should take around a week - to look at the peak usage.

I do know that 17.5 kWh is clearly better, but also I think at that config, it could be more expensive than the Tesla, without the islanding capability. I'm hoping to get my quote through in the next day or so.

We are tied in to Ecotricity till October. On the upside, we are only paying 18p per unit, on the downside, they only buy pack at 16p.

I wasn't aware of the Cosy tariff, but there's nothing to stop us changing to Octopus when our tie in to Ecotricity expires in October, so I guess I could use that cheap electricity to charge whichever battery.And as we haven't yet chosen our PV supplier….and the DNO then takes some time to come through, the timing isn't too bad.

I think the Sig 8 inverter is also 3 MPPTs.

I read somewhere that the Sig's multi peak scanning rescans every 10 minutes and in under 10 seconds and changes to the operating voltage across panels for optimal performance…..but no idea how it varies in real world performance over Tesla.

I've also had it suggested that Tesla support is better….but I'm sure someone selling Sig would say the opposite.

It's quite hard to choose!

NedS

Another factor that was really important for me when making our decision was cold weather performance. We had no choice but to locate our battery outside on the east wall of the house where it's fully exposed to what ever the weather can throw at it.

We purchased it primarily to reduce the costs of running the heat pump in winter, and to do that effectively we need to be able to recharge 3 times per day, even when it's -5C outside. I read about a lot of performance issues some other brands were having when it was very cold (below freezing) where the battery either couldn't charge or discharge at full rate (reduced performance) due to the cold temperatures. The Tesla was widely reported as having class leading thermal management, and we have seen no decreased performance in very cold weather which was important to us. Hopefully other manufacturers have caught up in this regard, but it's worth checking with other owners if this is important to you, especially if the numbers are tight for your particular use case (i.e, you have a 3h cheap rate window to recharge but the battery will only recharge slowly because it's very cold outside so cannot fully recharge in the cheap rate slot). It may perform fine installed in a utility room at 20C, but how does it perform when sat outside in 2 feet of snow.

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/82022472#Comment_82022472

Not sure how much this helps but I would have a skim through some of the genuine comments on Sigenergy's Trustpilot. For a company that's < 3 years old, it's scary reading.

From a product reliability/ design perspective, internal optimizers are a terrible idea, especially when poor aftersales is thrown into the mix. I suspect many will suffer from failures a few years down the road.

I have direct experience with Tesla's best in class cold weather performance and unit replacement warranty across several dozen households. No battery manufacturer replaces the entire unit in the 5th+ year of the warranty but Tesla continues to do so.

roadweary

https://forums.moneysavingexpert.com/discussion/comment/82022856#Comment_82022856

Doesn't look good, but how could I do a comparable for Tesla?

Screwdriva

Several PW3 owners on these forums - I’m sure some will chime in with their experiences. It’s important to read the brand’s feedback carefully to filter out the fake stuff (That said, not sure how much faith I’d put in feedback addressed to Elon directly).

In my experience spread across more than three dozen PW3 households, Tesla have been best in class!

Best of luck with the decision!

NedS

I have limited experience of Tesla's support. I have used their phone support once, shortly after installation where the installer forgot to set an option to allow export from the battery as well as solar (a common mistake), and Tesla were able to change the setting remotely whilst I was on the phone, so pleased with the outcome.

Hopefully I will never need their warranty support.