Apollo Solar: Why you should re-think charging your batteries with a diesel generator

The Pfeifer family has been in the energy delivery business for three generations. John’s grandfather delivered coal, his father delivered fuel oil, now John Pfeifer delivers sunshine! John is President and CEO of Apollo Solar, a designer and manufacturer of hybrid power equipment, who in 2002 was asked by NASA to get more power out of the solar panels and batteries on a high altitude balloon mission. They were able to harvest 30% more power from the same system. Apollo commercialized that solution and began deployment of the technology to the global market in 2005. The Apollo telecom power systems are now in their 3rd generation and installed on every continent with over 100 cell sites in Africa by way of an installation partnership with Camusat. TowerXchange met John Pfeifer at the Mobile World Congress in Barcelona to learn more…

TowerXchange: I’ve just listened to the CEO of MTN and MD of Airtel Africa explain that the biggest threat to the profitability of the African telecom business is the logistics, cost and scarcity of power – has solar technology evolved to the point where it could be the solution?

We all know that the cost of diesel is going up. In sub-Saharan, Central, a Southern African countries the current cost of diesel ranges from 80 US cents to US$ 1.80 per liter.  When we include maintenance and delivery costs plus a factor for theft, we agree that the diesel generator solution should be avoided.

Meanwhile, since 2007 the cost of installed solar has dropped dramatically.  Solar power is now about half the cost of diesel power, depending of course on the local cost of the diesel fuel and of the capex funding amortized to install the PV system.

Any operator reliant on diesel has a real problem. And in Africa, that means all the operators have a real problem, as do towercos acquiring passive infrastructure assets.

Apollo has identified a significant paradigm shift.  Based on the new much lower cost of solar, we advise our customers to avoid charging batteries with a diesel generator.  The batteries themselves represent about a 20% power loss over the charge-discharge round trip, so every dollar spent on diesel burned then stored in a battery becomes 20% more expensive.  Just use the expensive diesel fuel for power to the BTS directly and only when the weather makes solar power un-available.  Once the PV system is installed, the sunshine is free.  Use it to charge the batteries.

The smarter and higher-ROI solution for off-grid base stations is to operate on 100% solar, with enough PV and battery capacity for just over one day of autonomy.  When you need additional days of autonomy, add a small generator just to power the telecom equipment, rather than doubling or trebling solar panels or batteries.  There’s a sweet spot in the calculation of capex and opex where you’ve minimized cost of diesel – DG runtime might be reduced to just a few hours per month depending on the weather – essentially just what is required to maintain service on extremely dark days.  Of course every site is different and local parameters must be carefully analyzed to optimize the design for each specific site.

TowerXchange: Service level agreements often demand 99.5% uptime – tell us about the reliability of solar.

Solar is certainly much more reliable and maintenance-free than a generator of any description, but the electronics used to be the weakest part of solar power system.  If you want to damage electronics, heat it up, or if that doesn’t destroy it, subject it to repeated temperature cycles. Solar is the application from hell for electronics!  The electronics are subjected to the heat of the African sun during the day, and turned off at night when the ambient temperature is lowest. That type of heat and temperature cycling still won’t break Apollo systems, but it will break a lot of the low-cost solar solutions that are now available the market, and the logistical costs of replacing a US$2 electronics part when it might take days to reach the site will wipe out any capex savings pretty fast!

Apollo Solar’s charge controller was the only system to pass the US Army field test – they dragged it around behind a humvee over a bumpy track for 2000 km and then baked it in an oven but they couldn’t break it. The military rated DG wouldn’t start because it thought it was already over-heated, but the Apollo system continued to charge the battery.  Our equipment has been field tested by the US Army and Navy in temperature extremes, and it keeps working. Because we design all the hardware, develop our own software and assemble the telecom cabinets, we can provide standard five year warranties, extensions to ten years, and an SLA for the complete system, giving clients the reliability and operations security of a single point of responsibility.

TowerXchange: Procurement executives, CTOs and COOs at operators and towercos want to know that the equipment they’re considering installing is battle-hardened in Africa. What’s Apollo’s installed base in Africa?

We have a partnership with Camusat to deploy Apollo Solar sites for France Telecom-Orange.

Camusat has installed over 100 Apollo Solar units in Africa including in Madagascar, Egypt, Mali, Central African Republic and Kenya. Our equipment has also been installed in the US, Canada, Mexico, Peru and Chile – the latter installed by Leadcom.

Our first units were deployed in 2005, so they’re battle-hardened. We’ve taken the lumps, learned some lessons – this is our third generation system.

TowerXchange: Do you need a rocket scientist field engineer to install your kit?

We offer an Apollo person onsite for commissioning. But we supply an IP66 sealed electronics enclosure – the only requirement at installation is to bring in wires from PV array, battery and load, and maybe include optional alarms (for site security). The electronic cabinets are all factory programmed, pre-wired and tested, so limited engineering expertise is required. Getting the modem to work with the local telco tends to be the most complicated part of the process, as it has to be configured with a SIM card to talk on the network.

As for overcoming the logistics of getting equipment to remote cell sites, that’s why we partner with Camusat as they have earned a reputation for doing “whatever it takes to get it done” (see the Camusat profile here).

TowerXchange: How can you upgrade the system to provide power for multiple tenants?

We offer the cabinet in sizes from 4.2 to 33.6kW PV power. That means we can cover any telco DC load requirement from 500-4000W and have some power left over to charge mobile phones or provide some local lighting or refrigeration.

The largest tower owners in the world commonly use 4kW to 8kW of PV per base station. The Apollo outdoor cabinet has slots for four times 4kW of PV, supporting up to 16kw of PV. The cabinet can be installed with one 4kW Charge Controller and more can be added as more tenants sign up.

Upgrading for additional tenants is modular and simple - putting in an extra charge controller requires pushing a couple of buttons, supported by our guys who can be on the phone 24/7.

TowerXchange: What is unique about Apollo Solar’s charge controller?

Any rechargeable battery is only as good as the charging electronics. Our charge controller runs at 98% or better efficiency. Some of our best competitors run at 96.5%. Each of our T80HVs is able to deliver 80 amps at ambient temperatures up to 45°C, which is the highest temperature and highest battery current output of any charge controller in our market.

To extend the life of the battery, it is important to charge the system quickly and accurately and avoid overcharge. We know how to protect the battery life and prioritize that objective because batteries are an extremely large cost of remote cell sites. The Apollo System also has integral, near real-time remote monitoring – it’s updated every six seconds where some of our competitors update every hour. Our robust RMS monitors system access and PV theft, with alarm alerts to the NOC. The solar-hybrid systems also monitor all the essential details of the coupled generator.

TowerXchange: Tell us about the capital outlay required.

The cost of solar panels has plummeted to 60-70 US cents per watt. Our electronics cabinets start at $1 per watt, and we can do better than that in volume. The rest of the capex costs are related to installation logistics and the choice of batteries so the estimates are based on the site locale and battery market prices.